WO2018011417A1

WO2018011417A1 - Medical injector having safety feature preventing accidental expelling

Info

Publication number: WO2018011417A1
Application number: PCT/EP2017/067915
Authority: WO
Inventors: Martin Refslund Nielsen; Finn Hougaard
Original assignee: Novo Nordisk AS
Current assignee: Novo Nordisk AS
Priority date: 2016-07-15
Filing date: 2017-07-14
Publication date: 2018-01-18
Anticipated expiration: 2019-01-15

Abstract

The present invention relates to a medical injector (100, 100') for administering a drug from a held drug reservoir and comprising: a) a housing (220), b) an expelling assembly, c) an expelling enabler (350) movable from a first position wherein expelling is prevented to a second position wherein expelling is enabled, d) a cap (230) releasably attachable relative to the housing (220), and e) a fixation device (240) associated with the cap (230). The fixation device (240) defines at least one lever (250) configured for cooperating with the housing (220) and for pivotal movement towards and away from the expelling enabler (350). When the cap (230) assumes an attached state, and an impact force acts on the expelling enabler (350) urging it towards the second position, engagement between the housing (220) and the lever (250) acts to arrest the expelling enabler (350). The present invention further relates to a medical injector (100') comprising an inertia lock comprising an inertia member (700').

Description

MEDICAL INJECTOR HAVING SAFETY FEATURE PREVENTING ACCIDENTAL EXPELLING

FIELD OF THE INVENTION

The present invention relates to injection devices for injecting a medicament. In particular the present invention relates to medical injectors for expelling one or more doses of a drug from a held cartridge and improvements relating to the safety features of the device.

BACKGROUND OF THE INVENTION

In relation to some diseases patients must inject a medicament on a regular basis such as once weekly, once daily or even a plurality of times each day. In order to help patients overcome fear of needles, injection devices have been developed which include a needle shielding portion which slides relative to the housing for either unlocking the device or directly activating a dose expelling procedure.

Automatic injection devices have been developed with the aim of making the use of the injection device as simple as possible. Such devices are typically designed in a way that a user shall position the injection device onto the injection site and activate the device. The activation involves or causes insertion of a needle into the skin, ejection of a dose of the medicament and subsequently removal of the needle from the skin and into a shielded position.

Injection devices that provide automatic delivery of the medicament, i.e. auto-injectors, typically use a drive spring as driving force for the injection. Before use, the drive spring will be held in a pre-tensioned state from which it is released upon activation of the device. After activation the drive spring uses the energy from the tension to drive forward the piston of a cartridge. Examples of such injection devices are disclosed in WO 2012/022810 A2.

For many types of medical injectors, whether in their storage state or in their ready-to-use state, sudden impacts due to handling or due to an accidental drop of the medical injector may lead to uncontrolled consequences. One potential risk is that the medical injector may unintentionally become activated so that a dose is partly or fully expelled. This can lead to loss of the drug and may also cause the injection device becoming unavailable for performing a proper drug administration. The references WO 2009/0144594 A1 and WO 2014/009705 disclose various embodiments where a cap attaches to the housing of an injector device to retain an activation member thereby preventing the activation member from moving into an activation position.

Still, the solutions shown to date have not performed entirely satisfactorily. Many issues relating to manufacturing, robustness, long-term storage of the device and user friendliness call for improvements for the safety feature.

Having regard to the above-identified kind of prior art devices, it is an object of the present invention to provide a medical injector that includes an improved safety feature that safely maintains the injector in a non-expelling state even when being subjected to a potential force arising from an impact.

Yet additional further objects of the invention are to provide measures for obtaining devices having a superior performance and, at the same time, enabling manufacture at a reduced cost.

BRIEF DESCRIPTION OF THE INVENTION In a first aspect the invention relates to a medical injector for administering a drug from a held drug reservoir, the medical injector comprising: a housing, an expelling assembly configured for expelling one or more doses of a drug from a held drug reservoir, - an expelling enabler operably coupled to the expelling assembly and configured for translational movement relative to the housing along an axis from a first position wherein expelling is prevented to a second position wherein expelling is enabled, the expelling enabler defining a retention geometry, and a cap releasably attachable relative to the housing wherein, in an attached state, the cap protects a part of the housing and optionally the expelling enabler, and wherein, in a detached state, the expelling enabler is manually operable, The medical injector defines a fixation device cooperating with the cap and cooperating with the expelling enabler, wherein, in the attached state, the fixation device prevents the expelling enabler from being moved into the second position. The fixation device comprises at least one lever configured for engaging cooperation with the housing and for pivotal movement towards and away from the retention geometry. When the cap assumes the attached state, and an impact force acts on the expelling enabler urging it towards the second position, engagement between the housing and the lever acts to urge the at least one lever towards the retention geometry.

Such medical injector provides a favourable safety feature that is improved having regard to manufacturability, long-term storage and user friendliness. As the at least one lever may perform as a rigid beam that cooperates with the housing, substantive deflection of resilient control tabs or arms are avoided and potential issues with creep of components are reduced. The lever construction involves a principle that will tend to increase the retention of the expelling enabler as impact forces increase. At the same time, the design allows safe reattachment of the cap if a user should decide not to initiate the expelling activation but to postpone the drug administration, without running the risk of an accidental expelling activation when the cap is reattached. Further, the design allows for a user friendly cap interface and an appealing design with no or only few technical features visible from the exterior of the device.

The cap may be formed to define a cap casing defining a proximal open rim portion leading to a cavity configured for receiving the expelling enabler and a portion of the housing through said open rim portion. The fixation device may be accommodated at a distal end of the cap such as within the most distal half of the cavity of the cap. With the cap attached to the housing, a closed end of the cap may define a distal end.

The cap and the housing may define cooperating coupling means configured for releasably maintaining the cap in the attached state until a user exerts a force for releasing the cap relative to the housing.

The coupling means may be so configured that the cap is attached and/or detached relative to the housing by a translational movement along said axis and relative to the housing. In exemplary embodiments, coupling means are provided as means providing an axial snap connection. In certain embodiments, the translational movement for attachment or detachment of the cap does not require a relative rotational movement between the cap and the housing. Also, in certain embodiments, the attachment and/or the detachment can be performed irrespective of the relative angular orientation between the cap and the housing. In other embodiments, the movement for attachment and/or detachment of the cap may require a rotational relative movement between the cap and the housing. Also, in alternative embodiments, instead of being retained relative to the housing, the cap may be configured to cooperate with other components of the device, such as the expelling enabler, for releasably maintaining the cap attached to the remainder of the device.

The medical injector may be so configured that the cap can be detached and re-attached relative to the housing without causing the expelling enabler to be moved into its second position. Hence, the risk of unintentionally enabling expelling is minimized even in situations where the user should decide to recap the device prior to dose administration. The housing and the lever may be configured to remain disengaged during a substantial part of the attachment movement and/or during a substantial part of the detachment movement of the cap relative to the housing allowing said one or more levers to perform a pivotal movement and axially slide relative to the expelling enabler. In certain embodiments the housing and the lever are configured to remain disengaged during the entire attachment movement. Also, in certain embodiments, the housing and the lever are configured to remain disengaged during the entire detachment movement of the cap relative to the housing.

Respective ones of said at least one lever may form a beam shaped structure arranged for pivotal movement where the lever comprises a first surface portion configured for engaging a respective surface portion of the retention geometry of the expelling enabler and a second surface portion adapted for engaging a respective surface portion of the housing.

The beam shaped structure of each lever may extend substantially in parallel with said axis. The fulcrum (RP) of the lever may be axially located between the first surface portion and the second surface portion.

When the cap assumes the attached state the at least one lever may assume a position arranged radially between the expelling enabler and the cap.

Said pivotal movement may be provided so that the ends of the beam shaped structure move in a radial direction relative to said axis as the lever performs pivotal movement.

The beam shaped structure of each lever may comprise a proximal portion configured for cooperating with the housing and a distal portion for cooperating with the retention surface or the expelling enabler. In some embodiments, each lever is configured for pivotal movement so that the proximal end is urged radially outwards by its cooperation with the housing and so that the distal portion of the lever is urged radially inwards.

The cap may be configured to define a respective contact interface for engaging cooperation with each lever. For each of the levers said contact interface may at least in part define a fulcrum position (RP) for pivotal movement of the respective lever.

In certain embodiments the fixation device is non-detachably retained in a cavity formed by the cap. The fixation device may be attached relative to the cap in a manner preventing axial translational movement between the at least one lever and the cap. In other embodiments the fixation device is retained relative to the cap in a manner allowing limited axial translational movement of the fixation device relative to the cap. In such configuration, the fixation device may be arranged to be movable between a first axial position and a second axial position relative to the cap. The device may be so configured that the first axial position is assumed during the course of the attachment movement of the cap relative to the housing. Also the device may be so configured that the second axial position is assumed during the course of the detachment movement of the cap relative to the housing.

In certain embodiments, when an impact force acts on the expelling enabler urging it towards the second position, the fixation device assumes an intermediate axial position relative to the cap where the intermediate axial position is located between said first axial position and said second axial position. In some embodiments, when the fixation device assumes the intermediate axial position relative to the cap during an impact urging the expelling enabler towards the second axial position, the engagement between the lever and respective surfaces on the housing, the expelling enabler and a first subgroup of contact surfaces of the cap defines an impact fulcrum position (RPimpact) for pivotal movement of the lever, where the impact fulcrum position (RPimpact) is located at a different location than the fulcrum position (RP) of the lever with the fixation device assuming its second axial position relative to the cap.

In the same embodiment, or in other alternative embodiments, the device is configured for an impact fulcrum position (RPimpact) for pivotal movement of the lever where the impact fulcrum position (RPimpact) is located at a different location than the fulcrum position (RP) of the lever with the fixation device assuming its first axial position relative to the cap. During the attachment movement of the cap relative to the housing each of the at least one lever cooperates with surfaces of the cap and surfaces of the expelling enabler to define a fulcrum position (RP) for pivotal movement of the lever. This enables the lever to slide in a proximal direction relative to the expelling enabler. A proximally facing surface of the cap may cooperate with a distal facing surface of the lever to prevent the fixation device from moving beyond the first axial position relative to the cap.

During the detachment movement of the cap relative to the housing, the lever cooperates with surfaces of the cap and surfaces of the expelling enabler to define a fulcrum position (RP) for pivotal movement of the lever allowing the lever to slide in a distal direction relative to the expelling enabler. A distally facing surface of the cap may cooperate with a proximally facing surface of the lever to prevent the fixation device from moving beyond the second axial position relative to the cap.

For each of the at least one lever, the fulcrum position (RP) may be the same during attachment and detachment of the cap relative to the housing. However, in other embodiments, for a specific lever in question, the fulcrum position (RP) of each lever may shift from a first position during attachment to a second position during detachment.

The medical injector may be so configured that, when the medical injector is stored in its initial storage state with the cap attached, the fixation device assumes its first axial position relative to the cap. Upon a sudden impact where forces act for urging the expelling enabler towards the second position, the fixation device moves slightly in the proximal direction whereby each lever is pressed firmly against the housing. In particular embodiments this shifts the fulcrum position (RP) of each lever relative to the corresponding fulcrum position of the lever during the attachment movement and/or the fulcrum position of the lever during the detachment movement. Due to the shift in fulcrum position a potential impact force exerted on the expelling enabler urging it towards the second position transform into a moment that acts on the lever to pivot the lever into firm engagement with the retention geometry of the expelling enabler. An increase in impact force causes an increase in the force applied by the lever relative to the retention geometry of the expelling enabler. This prevents the expelling enabler from sliding in a proximal direction relative to the at least one lever of the fixation device and unintentional enablement of expelling is effectively avoided even during severe impacts. The fixation device may include only a single lever. In other exemplary embodiments, said at least one lever of the fixation device may form a plurality of levers where the number of levers may be chosen as two, three, four, five, six, seven, eight or even more separate levers. The levers may be arranged in a loop configuration that encircles the expelling enabler when the protective cap assumes the attached state.

In embodiments where the fixation device comprises as a plurality of levers, in a state where the cap assumes the attached state, said plurality of levers may be arranged evenly distributed in a cylindrical or conical configuration around the axis. In such arrangement, as long as the cap is maintained in the attached state, this provides a particular robust construction which is able to withstand severe impacts. This minimizes the risk of the expelling enabler being moved unintentionally into the second position where expelling is enabled.

The fixation device may comprise a flexible support structure that interconnects respective pairs of said plurality of levers allowing independent pivotal movement of each of said levers around its respective fulcrum (RP). In further embodiments, the flexible support structure enables radial expansion and radial compression of the plurality of levers. During cap attachment and detachment the flexible support structure enables the levers to move independently sideways relative to each other when the fixation device, with the plurality of levers, slides axially relative to the expelling enabler. The flexible support structure furthermore acts to retain the fixation device within the cap.

The medical injector may in certain embodiments define an autoinjector wherein the expelling enabler is configured for a triggering operation for causing the expelling assembly to expel a dose of drug as the expelling enabler is moved from the first position towards the second position. In other embodiments, the expelling enabler is configured as an initial lock that requires operation before a separate trigger activating member can be moved for causing a triggering operation. In other embodiments the medical injector defines an injector configured for manual drug expelling.

In particular embodiments the medical injector comprises an injection needle which is connectable or connected to a held drug reservoir, wherein the expelling enabler forms a needle shield which, when assuming the first position, is configured to cover the injection needle prior to and/or subsequent to expelling of a dose of drug from the reservoir. In some embodiments, the medical injector forms a single-shot injector adapted for expelling only a single dose of drug. Typically, such device may be formed as a pre-filled and, possibly, a disposable device. In other embodiments the medical injector forms a multi-shot injector configured for expelling a multitude of individual doses and wherein each expelling of each individual dose is enabled by moving the expelling enabler from the first position into the second position.

In a second aspect the present invention, as defined in any of the above mentioned variants, relates to an autoinjector configured for being triggered for expelling a single dose of drug from a held drug reservoir, such as a cartridge. The cartridge is held relative to a base which in some embodiments may define a housing and in other embodiments define a part which is mounted axially fixed relative to a housing. The cartridge comprises: a) an elongated body having a distal end and a proximal end and defining a central longitudinal axis, the body having a distally arranged outlet adapted for connection to a held needle, and b) a piston accommodated in the body, the piston configured for being driven axially in the distal direction to expel a dose of a drug through the outlet.

In some embodiments the expelling assembly comprises a plunger adapted upon triggering for moving in a distal direction relative to an initial axial position and transferring a force to move the piston, and an actuator providing stored energy, the actuator being configured for providing a force to act on the plunger to drive the piston of the cartridge distally. The expelling enabler defines a needle shield that is axially movable relative to the base in a proximal direction from an initial extended position via a triggering position to a trigger release position. The needle shield being may in some embodiments be prevented from rotating relative to the base. The expelling assembly may in some embodiments define a plunger release element that is operatively coupled to the plunger to prevent the plunger from moving distally relative to the plunger release element, wherein the plunger release element defines a thread and the base defines a thread adapted for engaging with the thread of the plunger release element. Prior to triggering, the plunger release element is held non-rotatable relative to the base and the plunger release element is retained in an initial axial position by means of the threaded engagement between the plunger release element and the base. The thread of the base may define a base thread component. The needle shield may be operatively coupled to the plunger release element to define a releasable retaining mechanism configured to, in an initial state where the needle shield assumes its initial extended position, retain the plunger release element threadedly engaged with the base thread in a predefined relative rotational and axial position where the force of the actuator provides bias for urging rotation of the plunger release element relative to the base thread in an expelling rotational direction. The needle shield is configured for operating the retaining mechanism to release the retaining of the plunger release element and the base thread component from the predefined rotational and axial position upon the needle shield being moved into its trigger release position. In some embodiments, geometries of the needle shield and the plunger release element define a pair of cooperating means that operatively couples the needle shield with the plunger release element, the pair of cooperating means being configured to induce or cause relative rotation between the plunger release element and the base thread component as the needle shield moves from the initial extended position towards the triggering position. In certain embodiments, the pair of cooperating means is formed so that the plunger release element rotates in a direction counter to the expelling rotational direction as the needle shield moves from the initial extended position towards the triggering position. In such embodiments, the cooperating means may further be formed so that the plunger release element rotates in the expelling rotational direction as the needle shield moves from the triggering position towards the trigger release position.

Still further beneficial embodiments are defined by the subject matter disclosed below in relation to the further aspects of the present invention.

In the autoinjector according to aspects of the invention, the device includes a needle shield triggered expelling assembly where the actuator, such as a pre-stressed actuating spring, is actuated for releasing axial movement of the plunger by a movement of the needle shield relative to the base.

The releasable retaining mechanism may define a lock. The autoinjector may be so configured that, prior to release of the lock while operatively coupling between the base thread component and the plunger release element is maintained, the force applied by the actuator transfers into a force having a force component that acts to rotate the base thread component and the plunger release element relative to each other. Depending on the particular design of the lock of the autoinjector the said force component can be utilized for designing the required force for moving the needle shield from the initial extended position to the triggering position.

The lock may be configured to include engaging first and second components having cooperating geometries that prior to activation engage to maintain the lock and which upon activation disengage and where the disengagement does not incorporate deformation of the cooperating geometries.

The cartridge body may define a proximally facing rear surface. The distally arranged outlet of the cartridge may comprise a pierceable septum adapted to be pierced by the rear needle of a needle unit having both a front needle extending in the distal direction and a rear needle extending in the proximal direction. In alternative configurations, the cartridge body outlet portion includes an injection needle fixedly attached relative to the cartridge body.

The cartridge may be mounted slideable relative to the base. In embodiments wherein the cartridge is not initially connected to a needle, the actuator may be configured to cause the plunger to move the cartridge distally for causing the rear needle to pierce the septum of the cartridge for subsequently moving the piston of the cartridge for expelling a dose.

In other embodiments, the cartridge is mounted at a fixed axial position relative to the base. In embodiments wherein the cartridge is not initially connected to a needle, the autoinjector may be configured to allow manually connecting a needle relative to the base so as to establish fluid connection between the cartridge and the needle. Alternatively, the cartridge may be provided in the form of a syringe having an injection needle fixedly attached to the cartridge barrel.

In some embodiments, the base forms a housing of the device. The autoinjector may accommodate a needle that is fixedly mounted relative to the base. In some embodiments, the front needle is configured to be manually operable relative to the needle shield such that when the needle shield is held against an injection site, manual operation of the front needle relative to the needle shield or vice versa causes manual penetration of the front needle into the injection site and causes subsequent release of the lock. By configuring the device so that a pushing force exerted manually on a part of the device is transferred to a manual force acting on the needle for manual penetration of the front needle into the injection site, the user gains improved control of the insertion of the injection needle. At the same time, by using this configuration the needle is hidden from the user during an administration. By providing an improved control of the needle insertion procedure a potential uneasiness for the user can be alleviated. The first part of the activation movement moves the needle forward relative to the needle shield to insert the needle in the user's skin. The second part of the movement activates the expelling assembly. In particular embodiments, this allows the user to manually insert the front tip of the needle before activating the device and an administration may be stopped in time should the user wish to abort the operation.

Relative rotational movement between the plunger release element and the base is performed around a first rotational axis. In some embodiments the first rotational axis is arranged coaxially with respect to the central longitudinal axis of the body of the cartridge. In other embodiments, the first rotational axis and the central longitudinal axis are arranged non-coaxially with respect to each other.

In the context of the present disclosure, when referring to "a base thread component", "a plunger release element defining a thread", and "a base thread component being adapted for operatively coupling with the thread of the plunger release element" this shall be so construed that when the thread of the plunger release element is operatively coupled with the base thread component the relative movement between the plunger release element and the base is provided by means of a helical guiding movement. The helical guiding movement may be provided by either a direct engagement between the plunger release element and the base or by an indirect coupling via one or more further components arranged between the base and the plunger release element. Non-limiting examples of a helical guiding movement includes a threaded coupling and a track and track follower coupling. A threaded coupling may be provided by means of co-operating screw threads having a constant lead along the first rotational axis or a variable lead along the first rotational axis. A threaded component may be provided by means of a continuous threaded section or by means of a plurality of thread segments. A track and track follower coupling may define a track having a constant pitch relative to said first rotational axis or a track having a varying pitch along the first rotational axis. When the helical guiding movement is provided by a threaded coupling, the threaded coupling may be formed as a non-self-locking threaded coupling. The threaded coupling may in exemplary embodiments be formed so that, for the initial position of the plunger, a thread segment of one component is axially interposed between two consecutive thread segments of the other component.

The thread of the plunger release element may be provided as an outer thread extending radially outwards from the plunger release element and configured to engage an inner thread component provided by the base thread component. Alternatively, the thread of the plunger release element may be provided as an inner thread component extending radially inwards from a side surface portion of an axial bore of the plunger release element configured to engage an outer thread component provided by the base thread component.

The needle may incorporate at least one cover providing a sterility barrier for covering at last the front needle of a held needle. In applications where a rear needle is present, sterility barriers for the rear needle may be incorporated. Each of the sterility barriers may be formed as a flexible cover or sheath configured as a closed cavity for accommodating at least a part of the needle, i.e. the front needle or the rear needle. The sterility barriers may be adapted to be pierced by the tip of the needle by moving the sterility barrier and the needle relatively to each other. For the front needle, the front cover may be operated for being pierced by the front needle by moving the needle shield relative to the base. For the rear needle, the rear cover may be operated for being pierced by the rear needle by moving the cartridge relative to the rear needle.

The injection device may comprise an actuator in the form of a stored energy source coupled to the plunger and configured for driving the plunger upon release of the lock. Non- limiting examples of a stored energy source include a spring element, such as a pre-strained spring, a compressed gas etc., wherein the stored energy may be accumulated during manufacture of the autoinjector. In other forms, the energy source is configured to become charged during an initial operation of the device prior to activation of the injection mechanism. The stored energy source stores sufficient energy to operate the autoinjector for expelling the total amount of drug that is intended to be expelled from a held cartridge, and, optionally, surplus energy for driving the cartridge forward for coupling to a rear needle and/or for driving the needle shield for a needle shielding operation. In particular forms, the actuator is provided as a helical compression spring that exerts an axial force on the plunger.

The plunger may be formed as a drive ram. The drive ram may be formed as a generally elongated cylindrical member retained at its proximal end relative to the plunger release element. Further, the plunger may include or operate through a spacing member positioned between the drive ram and the piston of the held cartridge. In some embodiments of the autoinjector the actuating spring is a helical compression spring arranged internally in a longitudinal bore of the drive ram. The drive ram may be made from a metal alloy, such as stainless steel. Alternatively, the drive ram may be made from a plastic material. In embodiments that include a drive ram, the plunger release element may be freely rotatable relative to the drive ram and/or the spacing member.

The plunger may be formed to integrally define a plunger release element wherein the plunger release component initially is in threaded engagement with the base thread component. In alternative embodiments, the plunger is coupled to a plunger release element formed as a generally sleeve formed threaded element. The plunger release element may define a central axial opening adapted to slidably receive the proximal end of the drive ram. The plunger may be prevented from moving distally relative to the plunger release element, at least while the thread of the plunger release element is engaged with the base thread. In certain embodiments, the plunger and the plunger release element are configured for being disengaged relative to each other upon the thread of the plunger release element having travelled a predefined axial distance in the base thread. Subsequently, the plunger is allowed to move distally relative to plunger release element. Examples of engagements that may be disengaged upon rotation include keyed engagements and threaded couplings.

In some embodiments the autoinjector may include a needle shield spring which is associated with the needle shield and the needle to urge the front needle into its shielded state or to urge the needle shield into the state where the front needle is shielded. In particular embodiments the needle shield spring is an element separate from the actuator or the actuating spring. Exemplary non-limiting embodiments of a needle shield spring include a spring element, such as a helical spring acting in compression mode and/or torsion mode, a leaf spring, a plastic spring or a plastic material spring element formed separately or integrally with other components of the autoinjector. The needle shield may be axially movable in the proximal direction relative to the base between an extended position, through a triggering position and into a collapsed position. In some embodiments, when the needle shield has been moved away from the extended position for triggering an unused device, the needle shield may be moved back in the distal direction.

In some embodiments of the autoinjector, the lock includes a first lock element that is axially movable as the needle shield moves from the extended position towards the collapsed position. The first lock element and the plunger release element define respective cooperating lock geometries configured to, prior to activation, maintain a rotational lock between the plunger release element and the base, the cooperating lock geometries being adapted to unlock to enable rotation between the plunger release element and base upon the needle shield being moved towards the collapsed position.

The first lock element may be formed integrally with the needle shield, as part of a needle shield sub-assembly or alternatively as a component separate from the needle shield but being operated by movement of the needle shield. The first lock element may be axially movable in the proximal direction relative to the base between an extended position, through a triggering position and into a collapsed position. In some embodiments, the first lock element forms a trigger element. The first lock element may be designed to follow the needle shield when the needle shield moves in a proximal direction for triggering the device. However, in some embodiments, the first lock element does not follow the needle shield for movements of the needle shield after the device has been triggered.

In particular embodiments of the autoinjector the first lock element is prevented from rotating relative to the base. The first lock element and the plunger release element define respective cooperating lock geometries configured to, prior to activation, maintain a rotational lock between the plunger release element and the first lock element, the cooperating lock geometries being adapted to unlock to enable rotation between the plunger release element and the first lock element upon the needle shield being moved towards the collapsed position.

In alternative embodiments the first lock element is allowed to rotate relative to the base when the needle shield has been pressed into its collapsed position but is prevented from rotating relative to the base when the needle shield is in the extended position. The first lock element and the plunger release element define respective cooperating geometries configured to prevent relative rotation but allowing axial displacement.

It is to be noted that, in accordance with one aspect of the invention, the lock needs only to remain enabled, that is to remain in locking mode, in the initial storage state, i.e. prior to activation of the expelling assembly. After activation of the expelling assembly the lock is not required to enter into locking mode again, i.e. the lock elements need not prevent relative rotation between the plunger release element and the base as the needle shield is returned to its extended position.

In some embodiments of the autoinjector the base thread component is fixedly disposed relative to the base, such as by being formed integrally with the base. When the base defines the housing or a section of the housing, the base thread component is thus axially and rotationally fixed relative to the housing.

In accordance with the first aspect, a track may be formed to extend at an angle with respect to the first rotational axis, such as less than 20degrees, alternatively less than 15 degrees, alternatively less than 10 degrees, and still alternatively less than 5 degrees. Such slightly angled axial track would in particular applications provide only a limited rotation between the plunger release element and the base thread component during axial displacement of the needle shield from the initial extended position and into the triggering position.

In other alternative embodiments of the autoinjector, wherein the base forms part of or defines a housing of the autoinjector, the base thread component is defined by a rotatable component that is axially fixed but rotatably mounted relative to the base. The lock includes a first lock element that is axially movable as the needle shield moves from the extended position towards the collapsed position. The first lock element and the rotatable component define respective cooperating lock geometries configured to, prior to activation, maintain a rotational lock between the rotatable component and the plunger, the cooperating lock geometries being adapted to unlock to enable rotation between the rotatable component and the plunger upon the needle shield being moved towards the collapsed position.

The first lock element may be prevented from rotating relative to the base. The first lock element and the rotatable component define respective cooperating lock geometries configured to, prior to activation, maintain a rotational lock between the rotatable component and the first lock element, the cooperating lock geometries being adapted to unlock to enable rotation between the rotatable component and the first lock element upon the needle shield being moved towards the collapsed position.

In such embodiments the plunger release element may be prevented from rotating relative to the base. In such embodiments the plunger may be mounted non-rotationally relative to the base and the plunger release element may be fixedly disposed on the plunger.

In some embodiments the first lock element defines a first lock feature and the rotatable component defines a cooperating lock feature, wherein one of the first lock feature and the cooperating lock feature defines an inclined track and wherein the other of the first lock feature and the cooperating lock feature defines a track follower. In such embodiment the inclined track may be formed as a track that extends with an angle relative to the first rotational axis. Hence, when the needle shield is moved from the extended position towards the collapsed position, the lock is released while inducing a relative rotation between the first lock element and the rotatable component. Subsequent to release of the lock, i.e. when the track follower disengages the track, rotation between the first lock element and the rotatable component enabled in accordance with the threaded engagement. Rotational movement between the rotatable component and the plunger is induced by the force exerted by the actuator due to the operative coupling of the thread components of the rotatable component and the plunger.

The axial track may be formed to extend at an angle with respect to the first rotational axis, such as less than 20degrees, alternatively less than 15 degrees, alternatively less than 10 degrees, and still alternatively less than 5 degrees. Such slightly angled axial track would provide only a limited rotation between the plunger and the base thread component during axial displacement of the needle shield from the initial extended position and into the triggering position. In some embodiments of the autoinjector the plunger release component is only operatively coupled with the base thread component during an initial first axial displacement of the plunger whereas, in a second axial displacement, the plunger release component is released from being operatively coupled with the base thread component allowing the plunger to subsequently continue axial displacement. Such release may occur after rotation of 90 degrees, such as 180 degrees, such as 270 degrees, such as 360 degrees, such as 1 or 2 complete revolutions. Subsequent to axial release of the plunger, the end of stroke position of the plunger may be provided by a pre-determined axial stop position of the plunger relative to the proximally facing rear surface of the cartridge. The autoinjector may be so configured that a stop geometry of the plunger directly engages the proximally facing rear surface of the cartridge. Alternatively, one or more intermediary components may be positioned between the plunger and the proximally facing rear surface of the cartridge to provide said pre-determined predetermined axial stop position of the plunger relative to the proximally facing rear surface of the cartridge.

In some embodiments of the autoinjector the plunger release element comprises a geometry having a radial dimension, such as a diameter, that is larger than the internal diameter of a cylindrical medicament section of the cartridge. In particular for autoinjectors having an actuator that stores a large amount of energy, the large dimensions of the thread component of the plunger release element enable a robust design that offers non-problematic long-term storage, even in situations where one or both of the thread components are made from a non-metallic material and where the actuator during long-term storage is kept in a pre- tensed state.

In particular embodiments, where the housing of the autoinjector has a total length of dimension L, the base thread component may be arranged to extend from the proximal end of the housing. The base thread component may be arranged to extend from the proximal end of the housing by less than 30 % of L, alternatively less than 20% of L, alternatively less than 10% of L, and still alternatively less than 5% of L.

In particular embodiments, the thread of the plunger release element may be dimensioned to extend from the proximal end of the plunger in the distal direction along the plunger by a length corresponding to less than 75% of the entire plunger length, alternatively by a length corresponding to less than 50% of the entire plunger length, alternatively by a length corresponding to less than 25% of the entire plunger length, and still alternatively by a length corresponding to less than 15% of the entire plunger length.

In some embodiments of the autoinjector the device irreplaceably accommodates a cartridge within the base and wherein the cartridge cannot be removed from the device without the use of tools. In some embodiments of the autoinjector the force acting for causing rotation between the plunger and the base for releasing the plunger from the initial axial position is at least partly exerted by the actuator. In particular embodiments, the force acting for causing rotation between the plunger and the base for releasing the plunger from the initial axial position is exclusively exerted by the actuator.

In embodiments incorporating a cartridge and a separate needle unit, the cartridge and the needle unit may be initially held in a configuration where the cartridge and the needle unit are separated by a distance. The actuator may be capable, upon release of the lock, to cause the cartridge and the rear needle to enter into the state where the cartridge septum is pierced by the rear needle and subsequently to cause the plunger to move to dispense the medicament through the needle.

The injection device may incorporate an activator formed by the housing which is mechanically associated with the needle so that when the activator and the needle shield is moved relative to each other it causes the front needle and the needle shield to move relative to each other. In some embodiments the needle substantially follows movement of the activator as the activator moves relative to the needle shield. In particular embodiments, the needle is attached to the activator in a way preventing relative axial movements between the activator and the needle.

In some embodiments the activator is configured to define a housing section which at least partly accommodates the cartridge and where the housing section is adapted to be gripped by the hand of the user. In such embodiment, the activator may be coupled to the needle to transfer a force from the activator to the needle when the activator is moved relative to the needle shield.

In a third aspect the invention relates to a medical injector for administering a drug from a held drug reservoir, the medical injector comprising: a base member, an expelling assembly configured for expelling one or more doses of a drug from the held drug reservoir, and an expelling enabler operably coupled to the expelling assembly and configured for movement relative to the base member along an axis in a first direction from a first position wherein expelling is prevented to a second position wherein expelling is enabled.

The medical injector is formed to define an inertia lock arranged between the base member and the expelling enabler. The inertia lock comprises an inertia member that assumes a first unblocking position when the medical injector is at rest and that moves into a second blocking position in response to an acceleration force above a predetermined level acting on the medical injector in a direction counter to the first direction The inertia member cooperates with the expelling enabler and the base to prevent the expelling enabler from being moved into the second position when the inertia member assumes the second blocking position, and wherein the inertia member allows the expelling enabler to become moved into the second position when the inertia member assumes the first unblocking position.

In accordance with the invention according to the third aspect, upon an accidental drop of the medicament injector, the inertia lock provides a safety means for reducing the likelihood that drug contained in the injector will be expelled from the medicament injector.

In some embodiments, the medical injector comprises a housing defining a distal end and a proximal end, and includes a distally arranged injection needle which is connectable or connected to said held drug reservoir. The housing may define said base. Alternatively, the base is provided as a separate component arranged relative to the housing, such as being mounted fixedly relative to the housing. In some forms the medical injector defines and extends along an axis, such as a longitudinal central axis. The reservoir may be provided as a septum equipped cartridge or syringe, wherein the longitudinal central axis runs through such cartridge or syringe.

In some embodiments the inertia member defines a first blocking surface which is configured to engage a second blocking surface of the expelling enabler when the inertia member assumes the second blocking position.

The inertia member may be configured reversibly movable between the first unblocking position and the second blocking position by a swivelling movement around a swivel point with an axis of rotation transverse to the first direction. The inertia member may be formed with a centre of mass that is positioned radially offset from said axis of rotation. In some embodiments the inertia lock comprises a mounting portion which is axially fixed relative to the base and wherein the inertia member is deflectably mounted relative to the mounting portion. In particular forms, the inertia member is biased towards the first unblocking position. In some embodiments the expelling enabler defines a mounting portion for the inertia member so that the mounting portion moves axially as the expelling enabler moves. Also in such configuration the inertia member is deflectably mounted relative to the mounting portion and the inertia member may be formed so as to be biased towards the first unblocking position. The inertia lock may be provided so that is comprises a deflectable portion that interconnects the inertia member with the mounting portion. The deflectable portion may be configured so as to form a film hinge. In other embodiments, the deflectable portion may comprise or be made of a spring element such as spring steel.

In certain configurations, the medical injector comprises a plurality of corresponding inertia members wherein each inertia member assumes a first unblocking position when the medical injector is at rest. Each of the inertia members is configured for moving into a second blocking position in response to said acceleration force above a predetermined level acting on the medical injector in a direction counter to the first direction.

In some embodiments the medical injector comprises a housing which defines said base, where the housing defines a distal end and a proximal end. The medical injector further comprises a distally arranged injection needle which is connectable or connected to said held drug reservoir.

In some forms the expelling enabler is configured to comprise a skin contacting member arranged at the distal end of the medical injector configured to engage and rest against the target skin area intended for needle insertion. The skin contacting member is made movable relative to the housing from a first distal position wherein expelling is prevented to a second proximal position wherein expelling is enabled.

In some forms the skin contacting member may be configured as a needle shield arranged to cover the injection needle prior to and/or subsequent to expelling of a dose of drug from the reservoir. In alternative forms the expelling enabler comprises a proximally arranged button configured for being operated by the hand of a user, i.e. the users fingers, and being movable relative to the housing from a first proximal position wherein expelling is prevented to a second distal position wherein expelling is enabled. In some configurations the medical injector defines an autoinjector for automatically expelling a dose of drug from the injector upon triggering of the autoinjector. In some embodiments, the expelling enabler is configured for triggering the expelling assembly to automatically expel a dose of drug as the expelling enabler is moved from the first position into the second position. In other forms, the expelling enabler performs as a safety member which is an additional operable member separate from a trigger element. The autoinjector may be configured so that operation of the trigger element for triggering the device can only be performed when the expelling enabler is in the second position.

In some configurations of the medical injector the device comprises a housing having a distal end and a proximal end, and includes a distally arranged injection needle which is connectable or connected to said held drug reservoir. The medical injector further comprises: a skin contacting member arranged at the distal end of the medical injector, the skin contacting member being movable from a first distal position wherein expelling is prevented to a second proximal position wherein expelling is enabled, and - a proximally arranged button configured for being operated by the hand of a user and being movable relative to the housing from a first proximal position wherein expelling is prevented to a second distal position wherein expelling is enabled.

In such configuration, one of the skin contacting member and the button defines said expelling enabler whereas the other of the skin contacting member and the button defines a trigger element which is configured for triggering the expelling assembly to automatically expel a dose of drug. Operation of the trigger element requires the expelling enabler to assume the second position to enable the trigger element to be moved from a non-triggering position to a triggering position.

In still further embodiments, all the above variants according to the third aspect may include any of the features or combination of features mentioned above in connection with the first and/or the second aspect. As used herein, the term "medicament" is meant to encompass any medicament-containing flowable drug capable of being passed through a delivery means such as a hollow needle or cannula in a controlled manner, such as a liquid, solution, gel or fine suspension. Also lyophilized drugs which prior to administration are dissolved into a liquid form is encompassed by the above definition. Representative medicaments includes pharmaceuticals such as peptides, proteins (e.g. insulin, insulin analogues and C-peptide), and hormones, biologically derived or active agents, hormonal and gene based agents, nutritional formulas and other substances in both solid (dispensed) or liquid form.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in further detail with reference to the drawings in which:

Figs. 1 a, 1 b and 1c show sectional front and side views of an exemplary embodiment of an autoinjector 100, the injection device being in an initial shielded state,

Figs. 2a, 2b and 2c show sectional front and side views of the device 100 illustrating a state where a front needle fully protrudes from a needle shield,

Figs. 3a, 3b and 3c show sectional front and side views of the device 100 illustrating a state where the cartridge has been connected to the needle for fluid delivery and wherein expelling has been initiated,

Figs. 4a and 4b show sectional front and side views of the device 100 illustrating a state where a predetermined dose of medicament from the cartridge has been expelled,

Figs. 5a, 5b and 5c show sectional front and side views of the device 100 illustrating a state where the needle shield has returned to the shielded state,

Fig. 6 is a detailed perspective view of a trigger element of the device 100,

Fig. 7 is a detailed perspective sectional view of a plunger release element of the device 100,

Fig. 8 shows a cross sectional view of a trigger components of the injection device 100, Fig. 9a is a partly cut perspective view of a top housing section of the injection device 100, Fig. 9b is a cross sectional perspective view of the trigger components of the injection device 100,

Fig. 9c is a partly cut cross sectional perspective view of the proximal part of the housing section 200, Fig. 10a shows a sectional side view of an exemplary first embodiment of an autoinjector 100' having a safety feature according to the third aspect of the invention, the autoinjector being in an initial storage state,

Fig. 10b shows a sectional side view of autoinjector 100', the autoinjector being in a state just prior to triggering, Fig. 10c shows a sectional side view of autoinjector 100', the autoinjector being in a state where the needle shield assumes a triggering position,

Fig. 10d shows a sectional side view of autoinjector 100', the autoinjector being in a state just subsequent to trigger release where the needle shield assumes a collapsed position, Figs 11 a through 1 1 d show representations of a modified trigger element, a modified top housing section and a modified plunger release element,

Figs. 12a-12c show schematic representations of a trigger element and a plunger release element in different states,

Figs. 13a and, 13b show perspective views of a fixation device of a safety feature according to a first aspect of the invention,

Fig. 13c shows a perspective cross sectional view of the fixation device shown in figs. 13a and 13b,

Fig. 13d shows a perspective cross sectional view of the fixation device shown in figs. 13a- 13c inserted and retained in a cap, Fig. 14a-14c show cross sectional plan views of the safety feature of the second embodiment in three different stages during attachment of the cap relative to the housing,

Fig. 14d and 14e are enlarged portions of the view shown in fig. 14a during cap attachment wherein force and movement vectors are indicated,

Fig. 15a-15b show cross sectional plan views of the safety feature of the second embodiment in two different stages during an impact,

Fig. 15c and 15d are enlarged portions of the view shown in fig. 15b during an impact wherein force and movement vectors are indicated, Fig. 16a-16c show cross sectional plan views of the safety feature of the second embodiment in three different stages during detachment of the cap relative to the housing,

Fig. 16d and 16e are enlarged portions of the view shown in fig. 14a during cap detachment wherein force and movement vectors are indicated, Fig. 17a shows a perspective view of a fixation device of a safety feature according to a third embodiment,

Fig. 17b show a perspective cross sectional view of a cap configured for receiving the fixation device shown in fig. 17a,

Fig. 18a shows a perspective view of a inertia lock device 700' of the autoinjector 100' shown in figs. 10a-10d, the inertia lock device being depicted in a relaxed or non- blocking state, and

Fig. 18b shows the autoinjector 100' of figs. 10a-10d during an accidental impact, the inertia lock device assuming a blocking state.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale, and certain features may be exaggerated or omitted in some of the drawings in order to better illustrate and explain the present invention. DESCRIPTION

The following is a description of various embodiments of a safety feature for a medical injection device. In some embodiments, the cap functions as, or incorporates, a safety member wherein the cap needs to be detached from the device before an expelling operation can be performed. When the cap is maintained attached to the device, the cap cooperates to retain an expelling enabler in a non-enabled first position until a drug administration is to be performed. Subsequent to detachment of the cap the expelling enabler is allowed to move into an enabled second position. In other embodiments, an inertia lock is incorporated into the medical injection device, wherein an inertia member is movable between a non-blocking position and a blocking position, and wherein, when exerted to an impact force the inertia member moves into the blocking position to prevent the expelling enabler to move into an enabled second position.

The safety feature may be incorporated into a variety of different types of medical injectors, such as needle based injectors. In some embodiments, the medical injector forms a single- shot injector adapted for expelling only a single dose of drug. In other embodiments the medical injector forms a multi-shot injector configured for expelling a multitude of individual doses and wherein each dose is enabled by moving the expelling enabler into the second position. Exemplary embodiments may encompass both as disposable devices of the pre- filled kind or devices intended for multiple use and offering replacement of a held drug reservoir. Suitable medical injectors may include injectors configured for manual drug expelling. However, in particular embodiments, the safety feature may be incorporated into an autoinjector wherein a stored energy source is releasable by a triggering action for automatic drug expelling, and where the safety feature prevents unintentional triggering.

In accordance with the invention, exemplary medical injectors may incorporate an expelling enabler which in certain embodiments may be provided as a manually movable control member which upon operation either enables movement of a separate expelling activation member or directly activates an expelling operation when the expelling enabler is moved from the first position to the second position. Examples of the latter type are disclosed in WO 2012/022810 A2. The following is a description of exemplary embodiments of a medical injection device for administering a pre-determined amount of a liquid medicament and which are suitable for incorporation of any safety feature variant in accordance with the present invention. However, the safety feature is not shown in the embodiment shown in figs. 1a through 9c but will be more thoroughly described in connection with figs. 10a through 18b.

The device 100 shown in figs. 1 a through 9c is an autoinjector configured for expelling a dose of a drug in a single administration where after the device 100 is ready for disposal. Figs. 1 a through 5c show various states of the injection device 100 during operation thereof with different views offering a detailed assessment of the operating principle.

It is to be noted that the group of figs. 1 c, 2c, 3c, 4a, 4b and 5c depicts a few more components than shown in the remaining illustrations spanning the series of figs. 1 a-5c. Furthermore, having regard to elements that during operation will deform into a deflected state, the first mentioned group of figures illustrates the true operational state of the deflected elements more correctly than the corresponding elements in figs. 1 a-5c.

Injection device 100 includes a generally tubular housing that extends along a central longitudinal axis. The housing forms a base that includes a lower housing section 220 arranged at a distal end of the device and a top housing section 200 arranged at a proximal end of the device. The lower housing section 220 and the top housing section 200 are joined to each other to form an enclosure to accommodate a medicament cartridge 600. As will be later discussed, the base is associated with a base thread 205.

Injection device 100 may further include a removable protective cap (not shown) that attaches to a distal end of the device 100 to protect a needle end of the device 100. The lower housing section 220 includes two opposing windows 222. When the cap has been removed from the device 100, the windows 222 allow visual inspection of the medicament contained within the device 100. In addition, windows 222 allow a user of the device to determine whether or not the device 100 has been used for an injection by inspecting the presence or the location of a piston of a medicament cartridge 600, or alternatively part of a plunger arrangement, arranged within the housing. In the shown embodiment top housing section 200 is for manufacturing reasons formed as an element separate from but permanently fixed to lower housing section 220 but may in alternative embodiments be formed integral with lower housing section 220.

Figs. 1 a, 1 b and 1c show front and side sectional views of the device 100 after the protective cap has been removed but in a condition prior to the administration operation. Shown protruding from the distal end of the lower housing section 220 is a needle shield 350 which is arranged coaxially and slidable relative to lower housing section 220. Needle shield 350 is slidable relative to the housing between a distal extended position where a front end of a needle assembly 500 arranged internally in lower housing section 220 is in a shielded state and a second proximal collapsed position where a front needle end of the needle assembly 500 protrudes through an aperture 354 arranged in the central part of a distal wall surface of the needle shield 350.

The injection device 100 is configured for being triggered to inject a dose when the needle shield 350 is moved from the distal extended position towards the collapsed position. The protective cap, when attached to the lower housing section 220, prevents the needle shield 350 from being manipulated and thereby prevents premature triggering of the injection device 100.

Lower housing section 220 accommodates a medicament filled cartridge 600 having an outlet 610 covered by a cartridge septum 620 adapted to be pierced by a needle for establishing fluid communication with the cartridge interior and having a slidably arranged piston 630. Piston 630 is driveable towards the outlet 610 when a needle pierces the cartridge septum 620 in order to dispense medicament from the cartridge 600. The dispensing is controlled by an expelling assembly. Cartridge 600 is arranged movable with respect to the lower housing section 220 from a proximal storage position to a distal active position. Distally in the lower housing section 220 is a needle unit in the form of a needle assembly 500 arranged in an initially separated configuration with respect to cartridge 600. In the shown embodiment, needle assembly 500 includes a needle cannula having a front needle 510 and a rear needle 520 respectively protruding in the distal and proximal directions from a needle hub 501 . Both front needle 510 and rear needle 520 include pointed tips 51 1 and 521 for respectively piercing the skin of a user and the cartridge septum 620.

As shown in fig. 1 c, the needle assembly 500 furthermore may include a front cover 512 and a rear cover 522 forming sterility sheaths for the front needle 510 and rear needle 520 respectively. Each of the front and the rear covers may be formed as a rubber sheath which is penetrable by the pointed tip portions of the needle 51 1/ 521 when the cover 512/522 is forced towards the needle hub 501. Prior to use of the device 100, each of the two covers 512/522 assumes the extended position in which the cover seals of the respective one of the front 510 and rear needle 520. The front and rear covers may be attached to the hub 501 either by gluing, welding, interference fit, a separate mounting element, or by corresponding means.

The needle cannula may be attached to the hub 501 by gluing, interference fit or similar joining process. In the embodiment shown, the hub 501 is an element separate from the housing but may in alternative embodiments be formed as a part of the housing 200/220. Hub 501 is formed as a generally tubular structure which extends proximally along the cartridge and even further to a position proximal to the cartridge. In this way the hub 501 supports the cartridge 600 along an exterior cylindrical wall of the cartridge. As such, the hub 501 is designed to perform as a cartridge holder relative to which the cartridge 600 is allowed to axially slide between the proximal storage position and into the distal active position.

In the shown embodiment, the needle hub 501 and hence the needle cannula is axially mounted relative to the housing of the device 100 so that the needle cannula follows axial movements of the housing when the housing is moved relative to the needle shield 350. In the shown embodiment, the needle shield 350 is formed as a generally tubular member having a distal face arranged to initially cover the front needle 510 and the front cover 512. The needle shield 350 is mounted slidable relative to the lower housing section 220 allowing limited axial movement by a predefined axial distance.

The needle shield 350 cooperates with a trigger element 380 which is located proximally to the needle shield 350. Trigger element 380 is also formed as a generally tubular element and extends axially in the proximally direction from the needle shield to a location close to the proximal end of top housing section 200. In the assembled state of the device 100, the needle shield 350 and the trigger element 380 perform as a single entity, i.e. the movement of trigger element 380 follows axial movement of the needle shield 350. Hence the trigger element 380 is movable from a distal end position corresponding to the extended position of the needle shield 350 to a proximal end position corresponding to the collapsed position of the needle shield 350. In the shown embodiment, each of the needle shield 350 and the trigger element 380 are mounted in a way that prevents rotational movement relative to the housing 200/220. A needle shield spring 340 is arranged between the housing section 200 and the trigger element 380. The trigger element 380 is urged in the distal direction by means of the needle shield spring 340 so that when no external applied force is exerted on the needle shield, the needle shield assumes its distal extended position which is shown in figs. 1a, 1 b and 1c. In this position a stop geometry on trigger element 380 and/or needle shield 350 prevents the two components from moving further in the distal direction. When an externally applied force is exerted on the needle shield 350 for moving the needle shield in the proximal direction relative to the housing, such as when device 100 is pressed with the needle shield against an injection site, the externally applied force acts counter to the force provided by the needle shield spring 340 resulting in the needle shield 350 and the trigger element 380 being forced to move in the proximal direction. When the needle shield 350 assumes the proximal collapsed position a proximal end surface of the trigger element 380 prevents the trigger element and the needle shield 350 from moving further proximally relative to the housing (cf. figs. 2a-2c).

As the device 100 is removed from the injection site, the needle shield 350 will move distally due to the force from the needle shield spring 340. After an injection has been performed, as the needle shield 350 reaches its distal position again, as shown in fig. 5c, it will be locked in this position to render the needle shield inoperable (to be further explained below).

The needle assembly 500 is arranged at the distal end of the lower housing section 220, such that the needle shield 350 completely covers the needle assembly when the needle shield is in its extended position. When the needle shield 350 is in its proximal collapsed position, the front needle 510 protrudes through the aperture 354 of needle shield 350.

As indicated in fig. 1 b, the cartridge 600 is maintained in its proximal storage position by means of two resilient arms 530 that extend radially inwards from the needle hub 501. In the initial state shown in fig. 1 b, the resilient arms 530 assume a position where they support and retain a neck portion of the cartridge 600 to prevent the cartridge from moving in the distal direction. The resilient arms 530 are adapted to flex radially outwards when sufficient force acting to move the cartridge 600 in the distal active position is exerted on cartridge 600. However, in the initial state where the needle shield 350 assumes its distal extended position, a blocking geometry 351 of the needle shield 350 encircles the resilient arms 530 to prevent them from flexing outwards and thus prevents the cartridge 600 from being moved distally. As will be described later, the blocking geometry 351 is configured to move axially when the needle shield 350 is moved into its proximal collapsed position making room for the resilient arms 530 to be flexed radially outwards. The expelling assembly of injection device 100 is based on a plunger arrangement that is driven in the distal direction along the central longitudinal axis of the device for advancing the piston 630 to thereby expel a dose from the cartridge 600. The plunger arrangement in the shown embodiment includes a drive ram 310 and a spacer member 400. In device 100 an actuator 330 is arranged in the proximal part of the device providing a stored energy source for exerting a distally directed force on drive ram 310. Spacer member 400 is a generally tubular member that is positioned between drive ram 310 and the piston 630 of the cartridge 600. Spacer member 400 acts as an intermediary member for transferring a force exerted by the drive ram 310 on the piston 630 for forwarding the piston in the distal direction. Spacer member additionally serves as a lock activator for a shield lock and for generating click sounds as the spacer member is advanced.

The actuator is provided in the form of actuating spring 330 that in the shown embodiment is provided as a pre-stressed helical compression spring. The actuating spring 330 is energized by straining the compression spring during manufacture of the device. The drive ram 310 is furthermore hollow to allow the actuating spring 330 to be positioned within the drive ram 310. A guiding element 360 arranged internally in actuation spring 330 assists in guiding the actuation spring 330 to prevent it from bending sideways. Guiding element 360 provides at its proximal end a seat portion arranged to act as a seat for supporting the proximal end of actuation spring 330. The spacer member 400 is formed with stop surfaces 401 positioned a predetermined distance from the distal end of spacer member 400 to cooperate with the rear end 611 of the cartridge 600 to thereby define a precise end of stroke position for the piston 630 inside cartridge 600. As the piston 630, during filling of the cartridge 600, can be accurately positioned with respect to the rear end 61 1 of the cartridge 600, the exact volume of an expelled dose can be accurately controlled by utilizing the stop surfaces 401 hitting the rear end 61 1 of cartridge 600 at completion of the expelling operation.

In the embodiment shown, spacer member 400 and a cooperating member associated with the housing may further include one or more pairs of click generating elements such as protrusions adapted to cooperate with click arms to generate click sounds during and/or at the completion of the injection.

As mentioned, in the shown embodiment, the actuator in the form of a pre-stressed actuation spring 330 urges the drive ram 310 in the distal direction. In the unactivated state of the injection device 100, a plunger release element 320 associated with drive ram 310 cooperates with the top housing section 200 and the trigger element 380 to retain the drive ram 310 in an initial axial position against the force of the actuation spring 330. Upon activation of the expelling assembly, i.e. by operating the trigger element, the plunger release element 320 is released allowing the drive ram 310 to thrust forward for providing a distally directed force on the piston 630 via the spacer member 400.

Alternatively to using a pre-stressed spring which is compressed during manufacture of the device, other embodiments of autoinjectors may include a mechanism for compressing the spring as an initial procedure when putting the device into use. Also, the actuator may in other embodiments be formed to include a torsion component, where the actuator is pre- stressed to exert a torsion force for driving forward a rotational drive of the expelling assembly. Alternatively, the actuator may be in the form of a compressed medium such as a gas. Still alternatively, the actuator may include a gas generator such as an electro-chemical cell. The drive ram 310 of the plunger arrangement is provided as a deep-drawn metal tube extending along the central longitudinal axis and defining a closed distal end and an open end portion having a collar extending radially outwards at its proximal end. The plunger release element 320 is arranged at the proximal end of the drive ram 310 to encircle the drive ram 310. Plunger release element 320 has an axial bore 321 defining a circumferential collar that rests against the collar of the drive ram 310 to prevent the drive ram 310 from moving distally relative to plunger release element 320. In the shown embodiment, the plunger release element 320 is freely rotatable relative to drive ram 310 and may, after triggering and soon after the cartridge 600 reaches the distal active position, slide axially forward relative to the drive ram 310. In the shown embodiment the plunger release element 320 is rotatable around a first rotational axis which is coaxial with the central longitudinal axis mentioned above.

Shown in greater detail on figs. 9a-9c plunger release element 320 defines a thread 325 that engages a thread 205 associated with the housing section 200 when the device 100 is in the initial state prior to triggering. A releasable lock serving as a retaining function acts to prevent relative rotation between the plunger release element 320 and the housing section 200, thereby maintaining the drive ram 310 in the initial axial position. In the shown embodiment, the releasable lock is provided by the trigger element 380 which in the initial distal position prevents relative rotational movements, induced by the actuating spring 330, between the plunger release element 320 and the housing section 200. As shown in figs. 6 and 8 axial tracks 386 of trigger element 380 are configured to be engaged by respective axial ribs 206 of top housing section 200 preventing the trigger element 380 from rotation relative to the housing 200/220 but enabling axial displacement. In the shown embodiment, two radially outwards extending protrusions 328 of plunger release element 320 are adapted to engage corresponding axial tracks or ribs 388 extending radially inwards on an inner surface of trigger element 380 (see figs. 5, 6 and 7). The axial tracks 388 each has a limited axial length defining circumferential neighbouring areas that are open at a location at the distal end of axial tracks 386. When sufficient axial displacement of the trigger element 380 relative to the plunger release element 320 has been obtained, rotation of plunger release element 320 is enabled. But in the initial state prior to triggering, as long as the trigger element 380 is situated distally relative to a pre-defined trigger release position, the plunger release element 320 is prevented from rotating. The trigger release position of the trigger element 380 is located at a point in close proximity but distally to the proximal end position of the trigger element 380.

As long as the plunger release element 320 is prevented from rotating relative to the housing the threaded engagement between the thread 325 of the plunger release element 320 and the thread 205 of the housing prevents the plunger release element 320 from being moved axially. Hence, prior to activation of the expelling assembly, the drive ram 310 is also prevented from being moved in the distal direction as long as the trigger element 380 is located distal to the trigger release position. In the shown embodiment, thread 325 and thread 205 are dimensioned to provide large surface areas to take up the force from actuator 330, enabling the use of plastic materials for the threaded components thereby providing low-friction engagement between components that operates during triggering.

In the shown embodiment, the lead of the threaded connection 325/205, the length of the threads and the dimensions of the engagement between the protrusions 328 and the axial tracks 388 are so configured that, upon displacement of the trigger element 380 towards the trigger release position, once the plunger release element 320 has been released for rotation and thus rotated slightly, the protrusions 328 cannot reengage the axial tracks 388. Hence, once the expelling assembly has been activated by exerting a force on the needle shield 350 for triggering the device, in case of a potential release in the force exerted on the needle shield, the distal movement of the drive ram 310 cannot be interrupted, i.e. the drive ram 310 will continue its distal movement until the intended end of dose position defined by the elements 401/611 .

Fig. 9a shows a partly cut perspective view of the top housing section 200 wherein the trigger element and the plunger release element 320 are visible. The plunger release element 320, the trigger element 380 and the top housing section 200 together form the main trigger components of the device. For clarity, the depicted view only shows selected components of the injection device 100 in the initial state prior to triggering but wherein additional components such as the actuating spring 330 and the drive ram 310 are omitted. The engagement between the thread 325 of the plunger release element 320 and the thread 205 of the housing section 200 is visible. Fig. 9b shows the trigger components in a sectional perspective view.

Referring back to fig. 1c and fig. 6, the trigger element 380 includes a pair of resilient arms 392 that partly constitutes a needle shield lock which renders the needle shield 350 permanently arrested when the needle shield, subsequent to finalisation of an injection, is returned to the extended position.

Each of the resilient arms 392 are configured to be flexed radially outwards away from a passive unbiased configuration and into a biased active configuration where the needle shield lock is provided. The passive unbiased configuration is best viewed fig. 1 a. Each of the resilient arms 392 forms an outer protrusion that is configured to enter into a corresponding recess 202 formed in housing section 200 when the needle shield 350 is to be arrested.

The said needle shield lock further incorporates a lock activator in form of a pair of thrust arms 402 associated with the plunger. In this embodiment the thrust arms 402 are formed by and extending radially outwards from the spacing member 400. The thrust arms 402 include a resilient section 403 that provides resiliency in the radial direction. When the axial position of the thrust arms 402 corresponds to the axial position of the resilient arms 392, each of the thrust arms 402 cooperates and exerts a radially outwards directed force on a respective resilient arm 392 to force the resilient arm 392 radially outwards. However, the radially outwards force exerted by the thrust arm 402 only moves the resilient arm 392 outwards and into its corresponding recess 202 after the drive ram 310 has reached its end of dose position. When the protrusions of each of the resilient arms 392 do not align axially with its corresponding recess 202, the resilient arm 392 is prevented from moving radially outwards. The needle shield or the trigger may further comprise a one or more contact surfaces each being resiliently slideable over a respective cooperating ramp surface formed in the housing. Referring to figs. 1 c, 6 and 9c, in the shown embodiment, the contact surfaces are provided by trigger element 380 as a pair of resilient snap arms 382 that are adapted to deform radially inwards relative to the shown unbiased position. Each snap arm 382 is configured to cooperate with a respective ramp section 212 formed along an internal wall surface in the proximal part of housing section 200. As best viewed in fig. 2c, each ramp section 212 is formed as an axial extending rib that is provided with a chamfered distal front section allowing the snap arm 382 to be deformed by the chamfered section of ramp section 212, when the trigger element 380 is moved from the distal end position to the proximal end position. The chamfered section of ramp section 282 connects to a ramp segment that continues in the proximal direction with a constant height, i.e. the ramp has an inner ramp surface extending parallel or substantial parallel with the first rotational axis.

When the needle shield 350 is moved from the distal extended position towards the proximal collapsed position, the snap arms 382 of the trigger element 380 and the corresponding ramp sections 212 provide resistance to movement the trigger 380 and thus also resistance to movement of the needle shield 350. Upon applying the autoinjector 100 at an injection site, a high axial force is created initially when the snap arms 382 hits the chamfered sections of ramp sections 212. Thus a high force is required for exertion on the needle shield 350 in order for the snap arms 382 to climb the ramp sections 212. As soon as the snap arms 382 have climbed the ramp sections 212, resulting in the snap arms 382 have been deformed radially inwards, the snap arms 382 travel and slide along the constant height ramp segments as the needle shield 350 is pushed further proximally relative to housing 200/220. This action requires considerable less force to be applied on the needle shield 350 than the initial high force. Hence, in accordance with the snap mechanism incorporating the snap arms 382 and the ramp sections 212, the needle shield displacement will occur in two stages, i.e. a first high force stage and a second low force stage. In the shown embodiment the position that the needle shield assumes between the two stages may be termed the "triggering position". In the shown design, the act of triggering will be virtually impossible to interrupt when the needle shield has passed the triggering position.

It will be appreciated, that the force needed for proximally displacing the needle shield will be largely independent from the force provided by the actuator 330, but will rather be decided by the force of the needle shield spring 340 and the force profile for the interaction between the snap arms 382 and the ramp sections 212. During displacement of the needle shield 350 relative to the housing 200/220, once static friction has been overcome, the frictional force acting against movement emanating from the force exerted by actuator 330 will be constant.

As will be discussed further below, the above mentioned pre-defined trigger release position of trigger element 380, and the corresponding position of needle shield 350, will be situated at the final part of the proximal movement of the needle shield where the snap arms 382 travel along the constant height ramp segments of ramp sections 212.

The high initial needle shield displacement force over a short distance assures that the needle shield is fully displaced and the autoinjector is effectively triggered due to the inertia of the human motion. In accordance herewith, the trigger release position may be positioned at a location where the snap arms 382 slide along the ramp sections 212 at the constant height ramp segments, preferably within the most proximal half of the path of interaction between the snap arms 382 and the constant height ramp segments of ramp sections 212.

The autoinjector may be so configured that the front cover 512 is only penetrated by the front needle 510 once the high initial force for bending the snap arms 382 radially inwards has been overcome, i.e. subsequent to the needle shield having reached the triggering position. Hence, the risk that a non-triggered but broached device may occur will be minimal.

In the following, while mainly referring to figs 1 a through 5c, operation of the injection device 100 will be described. As a first step in operating device 100, the previously mentioned protective cap is removed from the device. As mentioned above, figs. 1 a-1c show the device in its initial storage condition but with the protective cap being removed from the housing 200/220. The needle shield 350 is in its extended position whereby the front needle 510 is in a shielded state. Also the rear needle 520 is in a shielded state as the cartridge 600 assumes its initial position situated apart from the needle assembly 500.

In accordance with the above description, the housing 200/220 acts as an activator relative to the needle shield 350, in that, as the housing is gripped by the hand of the user and the distal end of device 100 is pressed against an injection site, the needle shield 350 will remain arrested relative to the skin and the housing moves distally relative to the needle shield 350 for activating the expelling assembly of the device 100.

As the device 100 is activated (cf. figs. 2a-2c) the needle shield 350 is moved in a proximal direction relative to lower housing section 220 with the distal end surface of the needle shield 350moving towards the needle assembly 500. The movement brings the front needle 510 through the small aperture 354 in the needle shield 350. As the needle cannula moves relative to the aperture 354 the above mentioned front cover 512 (see fig. 2c) is preferably held back by the geometry around the aperture 354, thereby allowing the front needle 510 to penetrate the front cover 512 while front cover is being compressed between the needle shield 350 and the needle hub 501. Alternatively the front cover could move through the aperture 354 as well. In such case the front cover would be pressed against the patient's skin, thereby being compressed between the device 100 and the injection site. The compression of the front cover can be either in a concertina-like way or be bent sideways, e.g. radially outwards. The front cover may have a specific geometry to ensure that the front cover is always compressed between needle shield 350 and needle hub 501 . The aperture 354 in the needle shield 350 could also have a specific geometry for ensuring correct compression of the front cover.

In the state shown in figs. 1 a-1c the trigger element 380 is in its distal position due to the pressure exerted by the needle shield spring 340. Cf. to fig. 9b, the releasable lock that rotationally locks the plunger release element 320 relative to the housing 200/220 is enabled and the drive ram 310 is therefore in its initial position. The cartridge 600 is positioned in its proximal storage position. The snap arms 382 have climbed the ramp sections 212, resulting in the snap arms 382 have been deformed radially inwards by the ramp sections 212 (see fig 2c). As the needle shield 350 reaches a predetermined position, i.e. the proximal collapsed position, the needle shield 350 will reach a stop limit, see figs. 2a, 2b and 2c. In this state the front needle 510 is inserted in the patient's skin at full depth and the front cover 512 is compressed (see fig. 2c). In accordance with the movement of the needle shield 350, the trigger element 380 has been moved into its proximal position, i.e. past the triggering position and even past the trigger release position.

As the trigger element 380 has been moved into its proximal position, the axial tracks 388 of trigger element 380 have become displaced so as to disengage from the engagement with the protrusions 328 of plunger release element 320. This situation is best viewed in fig. 2a. Due to the actuating spring 330 is exerting a force in the distal direction on drive ram 310 and plunger release element 320 the non-self-locking threaded engagement 325/205 will induce the plunger release element 320 to rotate. In fig. 2a and 2b, the plunger release element 320 has been rotated slightly relative to top housing section 200 and, in accordance with the threaded engagement, the plunger release element 320 and the drive ram 310 have been moved slightly axially in the distal direction. The initial spacing between the drive ram 310 and the spacing member 400 has been eliminated so that the force of the actuating spring 330 is enabled to act on the piston 630 of cartridge 600 by means of the drive ram 310 and the spacing member 400. The needle shield 350 and thus the blocking geometry 351 have been moved in the proximal position so that the resilient arms 530 are free to become deflected outwards. As shown in fig. 3a-3c- the force from the actuation spring 330 firstly displaces the drive ram 310, the spacing member 400 and the piston 630 a distance in the distal direction. During the first part of this stage the rear needle 520 is still separated from the septum 620 of the cartridge 600 and the cartridge is thus forced to move with the piston 630. The force of actuating spring 330 is sufficient to overcome the force needed for deflecting the resilient arms 530 outwards. Note however, that in fig. 3b and 4b, the resilient arms 351 are shown superposed relative to the wall sections of the cartridge 600. A more correct depiction of how the resilient arms 351 are actually deflected can be viewed in figs. 3c and 4b. Initially, as the cartridge 600 moves distally, the distance between the stop surface 401 of the spacer element 400 and the rear end 61 1 of the cartridge 600 remains unchanged as the piston 630 generally does not move relative to the body of the cartridge 600. However, after the cartridge 600 has been moved fully in the distal direction, the piston 630 begins its movement inside cartridge 600, the said distance decreases. In the state shown in fig. 3c cartridge 600 has been moved fully into its distal active position where it meets a stop feature formed in the needle hub 501. The rear needle 520 has penetrated the rear cover 522 and the rear cover has been compressed by the force exerted by the septum 620 of cartridge 600. Further, the rear needle 520 has penetrated the septum 620 of the cartridge. Hence, fluid communication between the needle cannula and the medicament contained in the cartridge 600 has been enabled. In this position the needle cannula is in contact with both the patient's skin and the medicament contained in the cartridge 600. After fluid communication between needle cannula and cartridge 600 is established the medicament is injected into the patient by means of the drive ram 310 being now forced relative to top housing section 200 and being urged distally by actuating spring 330. In the state shown in figs. 3a and 3b, the force exerted by the actuating spring 330 has acted on the drive ram 310 for expelling a first portion of the fluid from the cartridge 600. The actuating spring 330 continues to act on the piston 630 advancing the piston to a predefined end of dose position determined by the end of dose feature. When the stop surface 401 of spacer element 400 reaches the rear end 611 of the cartridge 600 the movement of the drive ram 310 is stopped, thereby stopping the expelling of the medicament (cf. fig. 4b).

Figs. 5a-5c shows the injection the device 100 after it has been retracted relative to the injection site. As the device is removed the needle shield 350 is moved forward relative to the lower housing section 220, the needle shield being urged by means of the needle shield spring 340, thereby releasing the compressive pressure on the front cover (not shown). In the shown embodiment, the front cover 512 remains in its collapsed position. In alternative embodiments the front cover will tend to return to its extended position covering the front needle 510.

As the device 100 is moved away from the patient the front needle 510 is removed from the skin of the patient. In embodiments where said front cover returns to its extended position, the front cover will prevent any excess medicament that is expelled from the needle cannula from dripping out of the device. The rear cover remains in its collapsed position due to the pressure from the cartridge 600.

As discussed above the needle shield 350 includes a lock which renders the needle shield 350 locked against proximal movements once it has been returned from the proximal collapsed position to the distal extended position, i.e. where the front needle 510 is in its shielded state. Referring particularly to fig. 5c, in the final state of the autoinjector, the resilient arms 392 have been pressed radially outwards into their biased active configuration by resilient parts 403 of the thrust arms 402 of spacing member 400. As the protrusions of the resilient arms 392 have been axially aligned with the corresponding recesses 202 in housing 200, the radially outwards movement of resilient arms 392 are allowed and hence the resilient arms 392 are moved into locking engagement directly with the housing section 200.

Close inspection of fig. 5c reveals that a proximal surface of each of the protrusions and the corresponding distal surface of the recesses 202 are formed with inclined sections tending to move the resilient arms outwards when increasing pressure is exerted in the proximal direction on needle shield 350. Hence, the locking of the needle shield in the distal extended position is effectively obtained even when excessive forces are applied onto the needle shield 350. In this state the autoinjector is ready for disposal.

Figures 10a-10d are cross sectional side views of an exemplary first embodiment of an autoinjector 100' which in accordance with an aspect of the invention includes a safety device in form of an inertia lock device 700', each view depicting one of four different operational states during the triggering procedure of the device. The inertia lock device 700' will be described more fully elsewhere in this disclosure and in connection with figs. 18a and 18b. In each view shown in figs. 10a-10d, which represents normal non-erroneous use of the device, the inertia lock device 700' assumes a relaxed non-blocking state and does not influence the operation of the device. However, as shown in fig. 18b, if the autoinjector 100' is being dropped on a hard surface such that an impact force F|_mpact acts upon the proximal portion of the device, the inertia lock device 700' shifts from the relaxed non-blocking state and enters into a blocking state preventing accidental movement of the needle shield.

Generally, the shown autoinjector 100' is functionally similar to the autoinjector embodiment 100 shown in figs. 1 a through 9c. However, features that relate to the trigger operation have been modified relative to the autoinjector 100. Whereas the autoinjector 100 shown in figs. 1 a through 9c includes a mechanism providing interaction between snap arms 382 and ramp sections 212 for generating a resistance to movement of the needle shield during needle shield displacement from the initial extended position towards the collapsed position, the autoinjector 100' includes a modified design omitting the said snap arms 382 and ramp sections 212.

Fig. 10a shows the autoinjector 100' in a state where a removable protective cap 230 is attached to a distal end of the device 100' to protect the needle end of the device. In fig. 10a the autoinjector 100' is in its initial storage state where the needle shield 350 is in its initial distal extended position wherein the needle assembly 500 is arranged separated from a proximal surface of the needle shield 350 and separated from a distal end surface of the cartridge 600. The needle assembly 500 includes a penetrable front needle cover 512 and a penetrable rear needle cover 522 respectively forming sterility sheaths for the front needle 510 and rear needle 520. Again, the autoinjector 100' includes a plunger arrangement comprising a drive ram 310 and spacer member 400. A rotatable plunger release element 320' functions as a plunger release controller for controlling release of the plunger arrangement. The drive ram 310 accommodates an actuating spring 330 and transfers the released actuating force through a spacer member 400 towards the piston of the cartridge 600. In the shown embodiment the spacer member 400 is mounted axially slideable but prevented from rotating relative to the housing. In the shown embodiment the drive ram 310 is not constrained rotationally in the housing. The plunger release element 320' is freely rotatable relative to drive ram 310. Hence, on triggering, the plunger release element easily rotates relative to the housing independent from rotational characteristics of the drive ram.

For the autoinjector 100', figs 11 a through 1 1 d provide representation of a modified trigger element 380', a modified top housing section 200' and a modified plunger release element 320'.

Fig. 11 a shows a perspective view of the modified trigger element 380' offering a view of one of a plurality of axial tracks 386' that are formed at an exterior surface of the trigger element 380' and arranged at the proximal end thereof. Fig. 1 1 b shows a perspective partly cut view of the trigger element 380' and a proximal fragment of top housing section 200'. Top housing section 200' includes a plurality of axial ribs 206' arranged at an inner surface to cooperate with respective axial tracks 386' of trigger element 380'. This arrangement prevents the trigger element 380' from rotating relative to the housing 2007220 but enables axial displacement of the trigger element 380'. Axial stops are further formed for limiting the axial movement of trigger element 380' and needle shield 350 relative to housing 2007220 between the initial extended position to the proximal end position, i.e. the collapsed position. As noted above, the needle shield and the trigger element are movable through the intermediately located triggering position and trigger release position.

Fig. 1 1 c is a partly cut perspective view of the modified trigger element 380'. Arranged at the proximal end of the trigger element 380', on a radially inward facing wall thereof, a plurality of control tracks 388' are formed where each control track 388' is configured to cooperate with a respective track follower 328' provided as a protrusion on a radially outwards facing surface of plunger release element 320' (see fig. 11 d). In the embodiment shown in fig. 1 c, the control track 388' comprises three consecutive segments, i.e. a first control track segments 388'a, a second control track segment 388'b and a release segment 388'c. The first control track segment 388'a includes an angled surface that is inclined with respect to the first rotational axis. Also, the second control track segment 388'b includes an angled surface that is inclined with respect to the first rotational axis but having a different orientation than the first control track segment 388'a. The proximal end of the second control track segment 388'b connects to the distal end of the first control track segment 388'a whereas the distal end of the first control track segment 388'b connects to the release segment 388'c.

In the shown embodiment, the track follower 328' of the modified plunger release element 320' exhibits a surface 328'a that is inclined with respect to the first rotational axis and in a way which corresponds to the inclined surface of the first control track segment 388'a so that when the autoinjector 100' assumes its initial state, i.e. the storage state, the surface 328'a is in intimate contact with at least a portion of the angled surface of the first control track segment 388'a. Figs. 12a-12c show schematic representations of the trigger element 380' and the plunger release element 320' in different states throughout the triggering procedure. For illustrative purposes, the remaining components have been omitted from figs. 12a-12c and a side portion of the trigger element 380' has been cut away offering a view of the distal portion of the plunger release element 320'. Fig. 12a shows the trigger element 380' and the plunger release element 320' in the initial state, cf. to fig. 10a. In this state the surface 328'a of plunger release element 320' is located at the first control track segment 388'a of the trigger element 380'. Due to the force exerted by the actuating spring 330 on the drive ram and the threaded connection 3257205' between the plunger release element 320' and the top housing section 200', a torque is exerted on plunger release element 320' for rotating the plunger release element 320' relative to the trigger element 380' in the expelling rotational direction so that the surface 328'a and the first control track segment 388'a are in abutment. The expelling rotational direction of the shown embodiment is the clockwise direction when viewed in the distal direction.

Fig. 10b shows the autoinjector 100' in a state where the cap 230 has been removed and the autoinjector 100' has been initially applied to an injection site applying a deliberate force on the housing of the device for triggering the device. The needle shield 350 and the trigger element 380' have been slightly forced in the proximal direction against the force of needle shield spring 340. Referring to fig. 12b which shows the trigger element 380' and the plunger release element 320 in positions corresponding to the state shown in fig. 10b, due to the inclination of the surface 328'a and the first control track segment 388'a, the plunger release element 320' has been induced to rotate in the rotational direction opposite the expelling rotational direction in the course of the first control track segment 388'a of the trigger element 380' having been moved proximally along the surface 328'a of plunger release element 320'. Correspondingly, the plunger release element 320' is rotated in accordance with the threaded connection 2057325' relative to the housing against the force of the actuating spring 330. In other words, the protrusion 328' travels uphill as the protrusion 328' slides up the inclined surface of the first control track segment 388'a.

As the actuating spring 330 exerts a considerable torque on the plunger release element 320' (by means of threaded connection 2057325') the resistance against moving the needle shield 350 in the proximal direction is relatively high, the resistance being largely decided by straining of the shield spring, the friction for moving the needle shield and the trigger element axially and the straining of the actuating spring. In the state shown in fig. 10b and 12b, the tip of the front needle 510 is still situated spaced away from the proximal surface of the needle shield 350 so that the front cover 512 has not yet been penetrated by the front needle 510 and the front cover has not yet been broached.

Theoretically, should the user wish to abort the triggering procedure at this point, the needle shield would be forced to return to the initial extended position, driven by the force of the needle shield spring 340 and the torque emanating from the actuating spring 330. Consequently, the plunger release element 320' would rotate back as the trigger element 380' would travel back to the location shown in fig. 10a and 12a. It is to be noted that in the state shown in figs. 10b and 12b the autoinjector 100' is not triggered for expelling a dose of drug as the plunger release element 320' is not yet able to rotate freely. However, in practice, the high initial needle shield displacement force over a short distance assures that the needle shield is fully displaced and the autoinjector is effectively triggered due to the inertia of the human motion. The state shown in fig. 10b and 12b the components effectively defines the above described triggering position. In the shown example, the axial displacement of the needle shield from the state shown in fig. 10a to the state shown in fig. 10b may be selected within the range of fractions of millimetres to a few millimetres, such as within 1 , 2 or 3 millimetres.

In the shown embodiment, when the needle shield 350 has been moved further proximally than shown in fig. 12b, the inclined surface of the second control track segment 388'b will be forced to slide over the protrusion 328' of plunger release element 320'. When the protrusion 328' is situated along segment 388'b the protrusion may be considered to travel downhill. This downhill movement is aided by the torque emanating from actuating spring 330 and acting on plunger release element 320' in the expelling rotational direction. As a consequence, the inertia of the human motion is allowed to progress unhindered only counteracted by the needle shield spring 340 and the autoinjector 100' is moved further relative to the injection site meaning that the needle shield 350 will be moved fully towards the collapsed position.

Fig. 10c and fig. 12c show the autoinjector 100' in a state where the needle shield 350 enters into a trigger release position where the plunger release element 320' will be fully released from cooperation with the trigger element 380'. This is accomplished by the trigger element 380' having been moved so that the protrusion 328' of plunger release element 320' meets the release segment 388'c. In the shown example, when the needle shield 350 assumes its trigger release position, the tip of the front needle 510 has penetrated the front cover 512 and the tip of the front needle protrudes distally from the needle shield 350. Release segment 388'c exhibits a steeply inclined surface so that the plunger release element 320' will be allowed to rotate unhindered. Fig. 10d shows this situation with the autoinjector 100' in a state where the needle shield 350 has entered into the collapsed position and the trigger element 380' has been moved fully proximal. Hence, the front needle 510 extends fully from the autoinjector corresponding to the pre-defined needle insertion depth. In Fig. 10d the plunger release element 320' has been allowed to rotate relative to the trigger element 380' to an extent so that the thread 325' has been moved approximately halfway out of the thread 205'. The plunger release element 320' and the drive ram 310 have consequently moved slightly in the distal direction forced by the axial force exerted by the actuating spring 330.

Distally to the release segment 388'c the trigger element 380' forms an opening having no parts that would interfere with the rotational and axial movement of the plunger release element 320'. Hence, once the protrusion 328' enters said opening, the plunger release element 320' rotates in accordance with the threaded connection 2057325' until the thread 325' of the plunger release element escapes the thread 205' of the top housing section 200'. In the shown embodiment, the threaded engagement is maintained while the drive ram 310 moves the cartridge distally in a first partial displacement. In the shown embodiment the threaded connection is maintained for approximately one complete revolution of the plunger release element 320'. The threaded engagement is maintained during about 80% of the total cartridge displacement and serves to reduce the speed of the drive ram as it moves distally prior to the expelling stage. In the shown embodiment, by utilizing the length of the threaded connection, the speed of the drive ram 310 will reach approximately half the velocity compared to the velocity of a corresponding drive ram not being controlled by the threaded engagement of the plunger release element 320', i.e. wherein a drive ram would be instantaneously released and pressed forward in a purely axial translational movement for the same axial displacement. Said reduction in speed is beneficial to reduce potentially damaging impact forces prior to the expelling procedure.

After the thread 325' of the plunger release element 320' escapes the thread 205' of the top housing section 200' the drive ram 310 will continue to move axially in the distal direction, initially for moving the cartridge 600 fully into its active position, and subsequently for expelling the dose of drug from the cartridge. The further operation of the autoinjector 100' will not be described herein as this generally corresponds to the operation principle described above in connection with the embodiment of the autoinjector 100 shown in fig. 1a through 9c.

It is to be noted that although the above described trigger element 380' shows control tracks 388' made up of rectilinear control track segments, the slope of the inclined surfaces of each said segments may be made non-linear such as by forming curved stretches for controlling the resistance against moving the needle shield 350 relative to the housing 2007220 as a function of distance travelled. Further, the slope of inclination of the individual segments may be made continuous or discontinuous. Also, the number of segments making up the control track 388 may be made different than the shown three-segment control track.

Referring again to fig. 10a, the injection device 100' comprises a cap 230 that attaches to the distal portion of the housing of the injection device to protect the device in the storage state.

The cap 230 and the housing 2007220 define cooperating coupling means configured for releasably maintaining the cap in the attached state until a user exerts a force for releasing the cap relative to the housing.

The coupling means may be so configured that the cap 230 is attached and/or detached relative to the housing by a translational movement along said axis and relative to the housing. In the shown embodiment, coupling means are provided as means providing an axial snap connection which does not require, but does not exclude, a relative rotational movement.

Turning now to fig. 18a this figure show a perspective view of the inertia lock device 700' which in the shown embodiment is provided as an individual component which is to be inserted and mounted in the housing 2007220 of the autoinjector 100'. The inertia lock device 700' is shown as a separate component which may be formed unitarily as a member being formed by a molding operation for example made of a plastics material. In this embodiment, the inertia lock device is formed as a generally cylindrical sleeve shaped member being dimensioned to be inserted inside the housing 2007220 at the proximal end thereof. With the inertia lock device 700' being in its rest state, i.e. where the inertia lock device assumes a non-blocking configuration, an inner aperture of the inertia lock device encircles and axially overlaps the proximal end of trigger element 380' when the trigger element assumes its proximal end position, the radially inwards surface of the inertia lock device 700' being in close proximity with the radially outwards surface of trigger element 380'.

The sleeve formed inertia lock device 700' includes a mounting structure 702' arranged to couple with the top housing section 200' so as to fix the inertial lock device 700' axially and rotationally relative to the housing. The mounting structure 702' of Inertia lock device 700' includes at its proximal end two halves of a circular rim portion, each rim portion having a proximally facing end surface which is configured to engage a mating surface of the top housing section 200' so that the inertia lock device 700' becomes axially fixedly mounted in the housing. Each of the circular rim portions are formed with a short axial dimension so that the circular rim portions exhibit a large degree of flexibility. Inertia lock device 700' further includes cut out portions so that areas adjoining the cut out portions define one or more individual inertia members 710'. In the shown embodiment two individual inertia members 710' are provided each being formed as an arcuate segment. Each inertia member connects exclusively with the remaining portions of the inertia lock device 700' by means of a circumferentially narrow bridging portion 705' at the proximal end of the respective inertia member 710', and circumferentially at a midpoint of the arcuate segment. The narrow bridging portion 705' connects midway at the respective one of the two halves of the circular rim portion. Each of the inertia members 710' is thus formed with a movable distal end i.e. configured movable from a relaxed state and radially inwards by flexure of the respective circular rim portion and the bridging portion 705'. In the shown embodiment, each of the inertia members 710', by virtue of said narrow bridging portion 705' and the rim portion, is supported in a manner so that it swivels around a swivel point having an axis of rotation which runs through the narrow portions and transverse to the central longitudinal axis. Hence, the distal end of each inertia member 710' is able to swivel radially inwards away from a relaxed unbiased position. When the inertia member 710' swivels radially inwards the rim portions and the bridging portions 705' are strained which then acts to urge the inertia members 710' back towards the relaxed unbiased position.

When the inertia members 710' assume their relaxed unbiased position they assume a first unblocking position. When the inertia members 710' have been flexed radially inwards they assume a second blocking position. Each of the inertia members 710' defines a distally facing blocking surface 719' which is configured to engage a proximally facing surface 389' of the trigger element 380' when the inertia members 710' assume the second blocking position. Hence, when the distally facing blocking surfaces 719' of the inertia members 710' engage with the proximally facing surface 389' of the trigger element 380' the trigger element 380' is prevented from being moved proximally relative to the Inertia lock device 700'. However, when the inertia members 710' assume the first unblocking position, the distally facing blocking surface 719' of the inertia members 710' are arranged radially outwards relative to the proximally facing surface 389' of the trigger element 380' allowing the trigger element 380' to be freely moved proximally relative to the Inertia lock device 700'. As the inertia members 710' are formed as arcuate segments, the centre of mass of each inertia member is positioned radially inwards from the swivel point. Hence, as shown in fig. a8a, when an acceleration force Fmertia acts on the inertia members 710' in the proximal direction, the inertia members 710' deflect inwards while swivelling around their swivel point. This condition is depicted in fig. 18b wherein the inertia members assume their second blocking position. The acceleration force F|_nertia may occur if the autoinjector 100' is accidentally dropped on a hard surface with the proximal end of the autoinjector being exerted to an impact force F|_mpact. Due to the mass of the needle shield 350 and trigger element 380' a resulting force F_Shie|_{d inertia} will act on these component urging them in the proximal direction. However, movement of the needle shield 350 and trigger element 380' in the proximal direction is prevented by the inertia members 710' because they each assume the second blocking position due to being acted upon by a radially inwards directed force Ben_ding- Hence, an effective means of preventing accidental triggering of the expelling procedure of the autoinjector is provided. It is to be noted that the safety feature provided by the inertia lock device 700' is effective both when the cap 230 is attached to the device, as shown in fig. 10a, but also when the cap 230 has been detached from the device as shown in fig. 10b.

It is to be noted that the inertia lock device 700' need not be arranged at the proximal end of the device but may in other embodiments be located at other locations. Also, in other embodiments, the inertia lock device may be arranged to travel with the needle shield 350 or the trigger element 380' relative to the housing. During an accidental impact, when the inertia lock device is exerted to extensive impact forces acting in the proximal direction, each of the one or more inertia members of the inertia lock device will move into its second blocking position preventing accidental triggering.

In further embodiments, an inertia lock device may be configured for preventing accidental movement of an operating button of an injection device, such as preventing operation of a trigger button, or operation of a button which in an autoinjector serves as a safety lock, wherein operation of the safety lock is required before triggering can be made by means of triggering movement of a needle shield.

In still other embodiments, an inertia lock device may be configured for preventing accidental movement of a skin contact member such as a needle shield of an injection device, wherein the skin contact member or needle shield serves as a safety lock, wherein operation of the safety lock is required before triggering can be made by means of triggering movement of a dedicated triggering button.

Reference is now made to a second embodiment of a safety feature which, as mentioned above, is operated by means of attachment and detachment of a cap. The second embodiment of such safety feature incorporates a fixation device 240 and is shown in figs. 13a through 16e. Referring to figs. 13a through 13c, these drawings show three different views of the fixation device 240 which may be incorporated into a slightly modified autoinjector, such as the autoinjector 100 shown in figs. 1 a through 9c, or, alternatively, the autoinjector 100' shown in figs. 10a through 12c. The safety feature incorporating fixation device 240 may be provided in combination with an inertia lock device, such as the inertia lock device 700' of the autoinjector 100', or in a stand-alone configuration as an alternative to the inertia lock device 700'. The fixation device 240 is intended to be accommodated and retained in a cavity of the cap 230 at the distal end thereof (see fig. 13d). The fixation device 240 comprises a series of levers 250, in the shown embodiment having four levers 250, arranged in a ring configuration where each individual lever is supported relative to neighbouring levers 250 by bridging parts of a flexible support structure 245. By means of the flexible support structure 245 the plurality of levers 150 assume a near cylindrical configuration which slightly narrows in the distal direction allowing the fixation device 240 to be accommodated radially between the needle shield 350 and the cap 230. In the unbiased state of the fixation device 240 shown in figs. 13a-13c, the radially inwards facing surface of the levers 250 are thus arranged in a slightly conical way which resembles a tapering outer surface portion of the needle shield 350. The tapering portion of the needle shield 350 is limited in the distal direction by a circumferential ledge portion arranged at the most distal portion of the needle shield 350, the circumferential ledge portion defining a retention geometry 352.

The flexible support structure 245 includes bridging parts that meander from the individual lever 250 to the neighbouring lever in a general circumferential direction. Due to the geometrical shape of the bridging parts of the flexible support structure 245 and the levers 250, each of the bridging parts are configured to be easily flexed whereas the levers 250 form individual rigid beams which are substantially non-flexible.

In the shown embodiment, the fixation device 240 is made as an injection moulded member of a polymer which allows the individual levers 250 to be moved in a pivotal manner around a respective fulcrum having an axis normal to the central longitudinal axis of the housing of the autoinjector. An exemplary material for the fixation device 240 includes polyoxymethylene plastic (POM) which has the suitable properties with regard to strength and flexibility at smaller deformation rates and which exhibits low-friction properties. Due to the meandering shape of the bridging parts of the flexible support structure 245, the ring configuration of the levers 250 are able to radially compress and radially expand relative to the unbiased state.

As best viewed in fig. 13a and 13b, each lever 250 includes, on its radially outwards facing surface, a first longitudinal extending recessed track 255 extending from the distal end of the lever to the axial location where the bridging part of the flexible support structure 245 connects with the lever. Further, each lever 250 includes, on its radially outwards facing surface, a second longitudinal extending recessed track 256 extending from the proximal end of the lever to the axial location where the bridging part of the flexible support structure 245 connects with the lever. Each lever 250 includes a first surface portion 252 at its distal end configured for engaging a respective surface portion of the retention geometry 352 of the needle shield 350 and a second surface portion 251 at the proximal end of the lever configured for engaging a respective surface portion 221 of the housing 220 (see figs. 15a and 15b). A radially inwards facing surface 253 of the lever exhibits a low-friction surface adapted to engage of the circumferential ledge portion of the needle shield 350 in a manner where the levers 250 slide easily relative to the needle shield.

Referring to fig. 13d, this figure shows a perspective cross sectional view where the fixation device 240 has been inserted into a distal part of the cavity formed by cap 230. On the inner surface of cap 230 a plurality of rib configurations are arranged, each rib configuration serving to mate with a respective lever 250 for retaining the fixation device 240 inside the cap and for controlling the movements that each lever is allowed to perform. Each rib configuration includes a first longitudinally extending rib 235 that is received in the first longitudinal extending recessed track 255 of the respective lever 250. Each rib configuration further includes a second longitudinal extending rib 236 that is received in the second longitudinal extending recessed track 256 of the respective lever 250.

In the shown embodiment, due to the shape of the rib configuration 235/236, the levers 250 are movable between a distal first axial position and a proximal second axial position relative to the cap 230. Hence, fixation device 240 is allowed for limited axial translational movement relative to the cap. A proximally facing surface of the cap 230 cooperates with a distal facing surface of the lever 250 to prevent the fixation device from moving beyond the first axial position relative to the cap. Also, a distally facing surface of the cap 230 cooperates with a proximally facing surface of the lever 250 to prevent the fixation device from moving beyond the second axial position relative to the cap. In the shown embodiment, the said proximally facing surface of the cap 230 is formed by the first longitudinally extending rib 235 whereas the said distally facing surface of the cap 230 is formed by the second longitudinally extending rib 236. However, in other embodiments, the said proximally distally facing surfaces need not be associated with the rib configurations but may be defined by other parts of the cap 230. Figs. 14a-14c show three cross sectional views of the most distal portion of an exemplary injection device where a cap 230 holding the fixation device 240 is being attached onto the distal part of the housing 220. Figs. 14a-14c represent three different states during the course of attachment of the cap 230 relative to the housing of the injection device. In the view shown in fig, 14a the injection device is in the initial state prior to triggering the expelling assembly and with the needle shield 350 in a first position, i.e. the initial extended position, where dose expelling is prevented and where the front part 510 of the needle cannula is shielded. In fig. 14a the cap has been moved in the proximal direction relative to housing 220 so that initial engagement between the circumferential ledge portion of the needle shield 350 and the plurality of levers 250 of fixation device 240. In the state shown in fig. 14a the second surface portion 251 at the proximal end of the levers are situated axially spaced apart from the distal portion of the housing 220. The fixation device 240 is positioned in the first axial position relative to the cap 230. Fig. 14b shows a state where the cap 230 has been moved closer towards the housing 220 but the cap has still not been fully progressed axially for full attachment relative to the housing. Each of the plurality of levers 250 has moved by a pivotal movement so that the distal ends of the levers are pivoted radially outwards allowing the fixation device 240 to slide axially relative to the needle shield 350 leaving the needle shield substantially unaffected so that the needle shield maintains its first position. In the state shown in fig. 14b, the proximal part of the levers 250 are still situated axially spaced apart from the distal portion of the housing 220.

The last stage of cap attachment is shown in fig. 14c where the cap 230 has progressed even further proximally and thus been fully attached relative to the housing 220 of the injection device. This movement has pulled the fixation device 240 with the levers 250 proximally relative to the housing 220 allowing the distal part of the levers to enter into a position proximal to the circumferential ledge portion of the needle shield 350. An inherent bias of the flexible support structure 245 of fixation device 240 has brought the distal ends of the levers 250 radially inwards into abutting contact with the radial outer surface of the needle shield 350 "behind" the circumferential ledge portion of the needle shield.

The state shown in fig. 14c represents the storage state of the injection device, as assembled by the manufacturer. For easy reference and comparison, the view shown in fig. 14c is also reproduced in the views shown in fig. 15a and fig. 16a. ,ln the storage state, due to manufacturing tolerances, a slight axial distance may be present between the distal ends of levers and the rim portion of the needle shield.

Fig. 14d and 14e are representations showing an enlarged portion of the view shown in fig. 14a during cap attachment where forces act on each lever 250. Due to the lever 250 interfacing with surface portions of the cap 230 and surface portions of the needle shield 350, at this particular condition, pivotal movement of the lever around fulcrum RP is enabled. As shown in fig. 14d the resulting reaction forces F_N__Shieid, F_N2_ca and F_Ni_ca that act on the lever 250 is indicated. This result in translational and pivotal movement of the lever 250 which is indicated in fig. 14e, meaning that the lever is moved proximally while the distal portion of the lever is moved radially outwards allowing the fixation member 240 to slide easily relative to the needle shield 350.

Figs. 15a and 15b provide insight in movement of key elements during a sudden impact which may occur if the injection device is accidentally dropped on a hard surface and where impact forces act for moving the needle shield towards the second position, i.e. the collapsed position.

Fig. 15a shows that the distal rim portion of the needle shield 350 defines a retention geometry 352 having a proximally facing surface configured to cooperate with the distally facing first surface portion 252 of the lever 250. The housing 220 includes a distal facing surface portion 221 configured to cooperate with the proximally facing second surface portion 251 of the lever. As shown, both of the interfaces located at opposite ends of the beam shaped lever (252/352 and 251/221 ) provide angled surfaces that serve to guide the elements relative to each other during relative movements and that serve to apply forces in directions being optimised for providing a robust design. During an impact where forces act for urging the needle shield towards the second position, the needle shield will in practical use allow a slight axial movement in the proximal direction. Firstly, this causes contact to be established between the retention geometry 352 and the distally facing first surface portion 252 of the lever 250. Secondly, it causes contact to be established between the proximally facing second surface portion 251 of the lever and the distal facing surface portion 221 of the housing. As a further result, the fixation device 240 is moved into an intermediate position between the first axial position and the second axial position relative to the cap 230.

Fig. 15c and 15d are representations showing an enlarged portion of the view shown in fig. 15b during an impact. Due to the lever 250 interfacing with surface portions of the cap 230, surface portions of the needle shield 350 and surface portions of the housing 220, in this particular condition, pivotal movement of the lever around fulcrum RPimpact is enabled. The location of RPimpact is different than the location of fulcrum RP during cap attachment. As shown in fig. 15c the resulting reaction forces F_N__Shieid, F_N__Cap and F_N_housing that act on the lever 250 is indicated. This result in pivotal movement of the lever 250 which is indicated in fig. 15d, meaning that the lever is urged for rotation so that the distal portion of the lever is pressed radially inwards towards the radially outer surface of the needle shield 350. Hence, an increase in impact force causes an increase in the force applied by the lever on the needle shield resulting in an effective fixation of the needle shield preventing further proximal movement of the needle shield.

Figs. 16a-16c show three cross sectional views where the cap 230 holding the fixation device 240 is being detached from the distal part of the housing 220. Figs. 16a-16c represent three different states during the course of detachment of the cap 230 relative to the housing of the injection device. In the view shown in fig, 16 is again shown in the storage state corresponding to fig. 14c wherein a slight axial distance is present between the distal surface portion 252 of levers and the retention geometry 352 of the needle shield. There is also a slight axial gap between the proximal portion 251 of the lever and the distal portion 221 of the housing.

Fig. 16b shows a state where the cap 230 has been moved slightly in the distal direction relative to the housing 220 but the cap has still not been fully detached. The distal movement of cap has caused the fixation device 240 with its lever 250 to be moved slightly distally so that the distal surface portion 252 of levers engages the retention geometry 352 of the needle shield. In this state the fixation device is in the second position relative to the cap. The axial gap between the proximal portion 251 of the lever and the distal portion 221 of the housing has increased.

A further stage during cap detachment is shown in fig. 16c where the levers 250 have been urged for pivotal movement so that their distal surface portion 252 have been forced radially outwards and moved distally past the retention geometry 352 of the needle shield.

Fig. 16d and 16e are representations showing an enlarged portion of the view shown in fig. 16b during cap detachment where forces act on each lever 250. Due to the lever 250 interfacing with surface portions of the cap 230 and surface portions of the needle shield 350, at this particular condition, pivotal movement of the lever around fulcrum RP is enabled. As shown in fig. 14d the resulting reaction forces F_{N shie}|_d, F_N2__cap and F_{N1 cap} that act on the lever 250 is indicated. This result in translational and pivotal movement of the lever 250 which is indicated in fig. 14e, meaning that the lever is moved distally while the distal portion of the lever is moved radially outwards allowing the fixation member 240 to slide with relative ease relative to the needle shield 350.

The cap 230 may subsequently be moved further distally to become completely separated from the housing 220, carrying with it the fixation device 240. The injection device is then in a condition ready for use for performing a drug administration procedure. Should the user change his mind for postponing an administration, the cap 230 may be reattached using the process indicated in figs. 14a-14e and the injection device is rendered in a safe state again where the cap with the fixation device serves to prevent the needle shield from moving into the second position. In this state, the device is again secured against unintentional firing during accidental drops.

In accordance with the principle described above the needle shield acts as an expelling enabler wherein a precondition for operating the expelling enabler is detachment of a cap.

Turning now to figs. 17a to 17c, a third embodiment of a safety feature is schematically shown. Again the cap comprises a fixation device 240' but with a slightly differing design compared to the safety feature of the second embodiment. Also the cap 230' is slightly modified.

As shown in fig. 17a, the fixation device 240' again comprises a plurality of levers 250 arranged in a ring configuration wherein each individual lever 250 is supported relative to neighbouring levers 250 by bridging parts of a flexible support structure 245. In this embodiment, twelve levers 250 are provided. Also, the flexible support structure 245 is ring- shaped and made of a metal or plastic material. Each of the plurality of levers 250, at a fixation point thereof, is attached to the flexible support structure 245 allowing each individual lever 250 to swivel around the fixation point.

The cap 230' includes, at an inner surface thereof, a ring-shaped groove 237 acting as a first retention means for retaining the flexible support structure 245 at a fixed location in cap 230'. A second retention means may be provided by ribs 235/236 for providing increased strength. In accordance with this, the fixation device 240' is attached at a fixed axial position in the cap 230'.

Fig. 17c shows a cross sectional plan view of the cap 230', the needle shield 350 and the fixation device 240' in a state corresponding to the storage state for the injection device. To improve clarity elements not directly associated with the safety feature have been omitted from the figure.

Disregarding the features connected to the axial movability of the fixation device 240 relative to the cap 230 of the second embodiment shown in figs. 13a-16e the operating principle for the third embodiment shown in figs. 17a-17c is generally similar. Hence, the third embodiment follows the same overall working principle, provides corresponding benefits and will not be further described herein.

Although the second and the third embodiments of the safety feature as shown and described herein have been designed with a fixation device being attached to the cap, the fixation device, and its levers, may in further embodiments be made integral with the cap, such as by injection molding with the cap casing.

Also, the principle of making the enablement of the expelling of the device dependent on the attachment condition of a cap may be utilized in other kinds of devices which are not directly activated by movement of a needle shield. For example, in a needle shield device, the needle shield may act as an expelling enabler wherein operation of the expelling enabler is a prerequisite for activating the expelling procedure by means of an individual manually operable member, such as a manually operable proximally arranged button. Also, in devices not incorporating a movable needle shield, the principle of making the enablement of the expelling assembly being dependent on the attachment condition of a cap may be utilized by coupling the cap with a manually operable activation button wherein activation of the activation button activates the expelling procedure.

Some preferred embodiments have been shown in the foregoing, but it should be stressed that the invention is not limited to these, but may be embodied in other ways within the subject matter defined in the following claims.

Claims

Claim 1. A medical injector for administering a drug from a held drug reservoir, the medical injector (100, 100') comprising: a housing (220), - an expelling assembly configured for expelling one or more doses of a drug from a held drug reservoir (600), an expelling enabler (350) operably coupled to the expelling assembly and configured for translational movement relative to the housing (220) along an axis from a first position wherein expelling is prevented to a second position wherein expelling is enabled, the expelling enabler (350) defining a retention geometry (352), and a cap (230) releasably attachable relative to the housing (220) wherein, in an attached state, the cap (230) protects the expelling enabler (350), and wherein, in a detached state, the expelling enabler (350) is accessible for being manually operated, wherein the medical injector defines a fixation device (240) cooperating with the cap (230) and cooperating with the expelling enabler (350), wherein, in the attached state, the fixation device (240) prevents the expelling enabler (350) from being moved into the second position, characterized in that the fixation device (240) comprises at least one lever (250) configured for engaging cooperation with the housing (220) and for pivotal movement towards and away from the retention geometry (352), wherein, when the cap (230) assumes the attached state, and an impact force acts on the expelling enabler (350) urging it towards the second position, engagement between the housing (220) and the lever (250) acts to urge the at least one lever (250) towards the retention geometry (352).

Claim 2. A medical injector as defined in claim 1 , wherein respective ones of said at least one lever (250) forms a beam shaped structure arranged for pivotal movement, the at least one lever (250) comprising a first surface portion (252) configured for engaging a respective surface portion of the retention geometry (352) of the expelling enabler (350) and a second surface portion (251 ) configured for engaging a respective surface portion (221 ) of the housing (220).

Claim 3. A medical injector as defined in claim 2, wherein the beam shaped structure of respective ones of said at least one lever (250) extends substantially in parallel with said axis and wherein the fulcrum (RP) of the lever (250) is positioned at an axial location between the first surface portion (252) and the second surface portion (251 ).

Claim 4. A medical injector as defined in any of the claims 1-3, wherein the cap (230) defines a contact interface configured for engaging with respective ones of said at least one lever (250) and wherein for each of said respective lever (250) said contact interface at least in part define a fulcrum position (RP) for pivotal movement of the respective lever (250).

Claim 5. A medical injector as defined in any of the claims 1-4, wherein the fixation device (240) is non-detachably retained in a cavity formed by the cap (230).

Claim 6. A medical injector defined in any of the claims 1-5, wherein the fixation device (240) is attached relative to the cap (230) in a manner preventing axial translational movement between the at least one lever (250) and the cap (230).

Claim 7. A medical injector as defined in any of the claims 1-5, wherein the fixation device (240) is retained relative to the cap (230) in a manner allowing limited axial translational movement of the fixation device (240) relative to the cap (230).

Claim 8. A medical injector as defined in claim 7, wherein the fixation device (240) is movable between a first axial position and a second axial position relative to the cap (230), the first axial position being assumed during the course of the attachment movement of the cap (230) relative to the housing (220) and the second axial position being assumed during the course of the detachment movement of the cap (230) relative to the housing (220).

Claim 9. A medical injector as defined in claim 8, wherein, when an impact force acts on the expelling enabler (350) urging it towards the second position, the fixation device (240) assumes an intermediate axial position relative to the cap (230), the intermediate axial position being located between said first axial position and said second axial position.

Claim 10. A medical injector as defined in claim 9, wherein, when the fixation device (240) assumes the intermediate axial position relative to the cap (230) during an impact, the engagement between the lever (250) and respective surfaces on the housing (220), the expelling enabler (350) and a first subgroup of contact surfaces of the cap (230) defines an impact fulcrum position (RPimpact) for pivotal movement of the lever (250), where the impact fulcrum position (RPimpact) is located at a different location than the fulcrum position (RP) of the lever (250) with the fixation device (240) assuming its second axial position relative to the cap (230).

Claim 1 1. A medical injector as defined in any of the claims 1-9, wherein said at least one lever (250) of the fixation device (240) is provided as a plurality of levers (250), wherein with the cap (230) assuming the attached state, said plurality of levers (250) are arranged evenly distributed in a cylindrical or conical configuration around the axis.

Claim 12. A medical injector as defined in claim 11 , wherein a flexible support structure (245) interconnects respective pairs of said plurality of levers (250) allowing independent pivotal movement of each of said levers (250) around its respective fulcrum (RP).

Claim 13. A medical injector as defined in claim 12, wherein the flexible support structure (245) enables radial expansion and radial compression of the plurality of levers (250).

Claim 14. A medical injector as defined in any of claims 1 -13, wherein the medical injector (100,100') defines an autoinjector and wherein the expelling enabler (350) is configured for triggering the expelling assembly to expel a dose of drug as the expelling enabler (350) is moved from the first position towards the second position.

Claim 15. A medical injector as defined in any of claims 1 -14, wherein the medical injector (100, 100') comprises an injection needle (500) which is connectable or connected to a held drug reservoir (600), wherein the expelling enabler (350) forms a needle shield which, when assuming the first position, is configured to cover the injection needle (500) prior to and/or subsequent to expelling of a dose of drug from the reservoir (600).

Claim 16. A medical injector for administering a drug from a held drug reservoir, the medical injector (100') comprising: a base member (200', 220), an expelling assembly (310, 330, 400) configured for expelling one or more doses of a drug from the held drug reservoir (600), and an expelling enabler (350, 380') operably coupled to the expelling assembly (310, 330, 400) and configured for movement relative to the base member (200', 220) along an axis in a first direction from a first position wherein expelling is prevented to a second position wherein expelling is enabled, wherein the medical injector (100') defines an inertia lock arranged between the base member (200', 220) and the expelling enabler (350, 380'), the inertia lock comprising an inertia member (710') that assumes a first unblocking position when the medical injector (100') is at rest and that moves into a second blocking position in response to an acceleration force above a predetermined level acting on the medical injector (100') in a direction counter to the first direction, and wherein the inertia member (710') cooperates with the expelling enabler (350, 380') and the base (200', 220) to prevent the expelling enabler (350, 380') from being moved into the second position when the inertia member (710') assumes the second blocking position, and wherein the inertia member (710') allows the expelling enabler (350, 380') to become moved into the second position when the inertia member (710') assumes the first unblocking position.

Claim 17. A medical injector as defined in claim 16, wherein the inertia member (710') defines a first blocking surface (719') which is configured to engage a second blocking surface (389') of the expelling enabler (350, 380') when the inertia member (710') assumes the second blocking position.

Claim 18. A medical injector as defined in any of claims 16-17, wherein the inertia member (710') is reversibly movable between the first unblocking position and the second blocking position by a swivelling movement around a swivel point (705') with an axis of rotation transverse to the first direction, and wherein the inertia member (710') has a centre of mass that is positioned radially offset from said axis of rotation.

Claim 19. A medical injector as defined in any of claims 16-18, wherein the inertia lock comprises a mounting portion (702') which is axially fixed relative to the base (200', 220), wherein the inertia member (710') is deflectably mounted relative to the mounting portion (702'), and wherein the inertia member (710') is biased towards the first unblocking position.

Claim 20. A medical injector as defined in any of claims 16-18, wherein the expelling enabler (350, 380') defines a mounting portion for the inertia member (710'), wherein the mounting portion moves axially as the expelling enabler (350, 380') moves, wherein the inertia member (710') is deflectably mounted relative to the mounting portion, and wherein the inertia member (710') is biased towards the first unblocking position.

Claim 21. A medical injector as defined in any of claims 19-20, wherein the inertia lock comprises a deflectable portion (705') that interconnects the inertia member (710') with the mounting portion (702').

Claim 22. A medical injector as defined in any of claims 16-21 , wherein the inertia member (710') defines one of a plurality of corresponding inertia members (710'), each inertia member (710') assuming a first unblocking position when the medical injector (100') is at rest and configured for moving into a second blocking position in response to said acceleration force above a predetermined level acting on the medical injector (100') in a direction counter to the first direction.

Claim 23. A medical injector as defined in any of claims 16-22, wherein the medical injector (100') comprises a housing (200', 220) having a distal end and a proximal end, the medical injector (100') further comprising a distally arranged injection needle (500) which is connectable or connected to said held drug reservoir (600), wherein the expelling enabler (350, 380') comprises a skin contacting member (350) arranged at the distal end of the medical injector (100'), the skin contacting member (350) being movable from a first distal position wherein expelling is prevented to a second proximal position wherein expelling is enabled.

Claim 24. A medical injector as defined in claim 23, wherein the skin contacting member (350) defines a needle shield configured to cover the injection needle (500) prior to and/or subsequent to expelling of a dose of drug from the reservoir (600).

Claim 25. A medical injector as defined in any of claims 16-22, wherein the medical injector (100') comprises a housing (200', 220) having a distal end and a proximal end, the medical injector (100') further comprising a distally arranged injection needle (500) which is connectable or connected to said held drug reservoir (600), wherein the expelling enabler (350, 380') comprises a proximally arranged button configured for being operated by the hand of a user and being movable relative to the housing from a first proximal position wherein expelling is prevented to a second distal position wherein expelling is enabled.

Claim 26. A medical injector as defined in any of claims 16-25, wherein the medical injector (100') defines an autoinjector and wherein the expelling enabler (350, 380') is configured for triggering the expelling assembly (310, 330, 400) to expel a dose of drug as the expelling enabler (350, 380') is moved from the first position into the second position.

Claim 27. A medical injector as defined in any of claims 25, wherein the medical injector wherein the medical injector (100') comprises a housing (200', 220) having a distal end and a proximal end, the medical injector (100') further comprising a distally arranged injection needle (500) which is connectable or connected to said held drug reservoir (600), wherein the medical injector (100') further comprises: - a skin contacting member (350) arranged at the distal end of the medical injector (100'), the skin contacting member (350) being movable from a first distal position wherein expelling is prevented to a second proximal position wherein expelling is enabled, and a proximally arranged button configured for being operated by the hand of a user and being movable relative to the housing from a first proximal position wherein expelling is prevented to a second distal position wherein expelling is enabled, wherein one of the skin contacting member and the button defines said expelling enabler (350, 380'), and the other of the skin contacting member and the button defines a trigger element is configured for triggering the expelling assembly (310, 330, 400) to expel a dose of drug, wherein operation of the trigger element requires the expelling enabler (350, 380') to assume the second position to enable the trigger element to be moved from a non-triggering position to a triggering position,