GB2549964A

GB2549964A - Medicament delivery devices

Info

Publication number: GB2549964A
Application number: GB1607794.3A
Authority: GB
Inventors: Paul Grimoldby James
Original assignee: Owen Mumford Ltd
Current assignee: Owen Mumford Ltd
Priority date: 2016-05-04
Filing date: 2016-05-04
Publication date: 2017-11-08
Also published as: GB201607794D0; WO2017191446A1

Abstract

An injection device 100 for delivery of a medicament from a container 12. A drive mechanism 200,300,330 is arranged to apply an insertion force to move a needle 16 from a starting position to an insertion position. An interlock member 250 received in the housing 110 is moveable from: a first locked position to a second position where the drive mechanism 200,300,330 can be activated; and then to a third position in which an opaque distal end region 254 of the interlock member 250 shrouds the needle 16 after injection of the medicament. A window 114 is provided to allow at least a part of the container 12 to be viewed from outside the housing 110. The interlock member 250 comprises a transparent region 252 disposed between the container 12 and the window 114 during at least part of the operating sequence of the device. Preferably the interlock member 250 is turnable with respect to the housing 110, the transparent region 252 being arranged so that container 12 remains visible through window 114 when the interlock member 250 is turned and where the injection device 100 may further comprise a dose setting mechanism comprising a turnable dose selector 140.

Description

MEDICAMENT DELIVERY DEVICES

The present invention relates to devices suitable for the delivery of a medicament to a patient. In particular, but not exclusively, the invention relates to variable-dose, singleuse auto-injection devices for subcutaneous or hypodermic injection of a medicament from a pre-filled container.

Injection devices designed for automatic or semi-automatic delivery of a single dose of a medicament are known in the art. Such devices typically include a housing that allows the user to grip the device, a pre-filled container containing the medicament, and a firing mechanism. The pre-filled container includes a tubular glass body or barrel, and a stopper slidably received in the body. A distal end of the container forms an outlet for the medicament. Commonly, the container is a pre-filled syringe, and a staked hypodermic needle is provided at the distal end of the syringe body. A removable needle shield is typically provided to seal the needle prior to use. The needle shield is typically of two-part construction, with an elastomeric inner part for receiving the needle and a rigid outer cap or cover which is attached to the inner part and can be gripped by a user to pull the shield off the needle. This shield arrangement is known in the art as a rigid needle shield (RNS). One or more radially-projecting flanges are provided on the proximal end of the syringe body, which can be used to retain the syringe in the device. One example of a pre-filled syringe with a rigid needle shield is available under the registered trade mark Hypak (Becton Dickinson, New Jersey, USA).

With the syringe in place in the housing of the device, the distal end of the housing is closed by a deshielder cap. To prepare the device for use, the cap is removed. The cap is arranged to grip the rigid needle shield, so that removal of the cap pulls the rigid needle shield off the needle. The distal end of the housing is then placed against the skin. When activated, a spring-loaded plunger of the firing mechanism is released to push the stopper of the syringe distally towards the needle to inject the medicament.

In some devices, known as auto-injectors, needle insertion is also automatic. In such devices, the needle is initially retracted in the housing. During an initial phase of operation of the firing mechanism, the firing mechanism applies an insertion force to the syringe body to cause the syringe to move distally with respect to the housing to an insertion position. As a result, the needle advances out of the housing and into the patient’s skin before injection of the medicament. After the injection has taken place, the device can be pulled away from the skin to withdraw the needle from the injection site.

Various safety features are typically included in auto-injector devices. For example, it is known to provide a viewing window or aperture in the housing of the device, so that at least part of the syringe can be seen from outside the housing. In this way, the integrity of the syringe and the appearance of the medicament can be checked before the device is used. Furthermore, the stopper and the plunger may become visible through the window as delivery of the medicament proceeds, allowing a visual indication that the delivery of the medicament is complete. For the same reason, an injector that has already been used can be easily identified by inspection through the window.

To prevent accidental operation of an auto-injector device, an interlock arrangement may be provided. In one such arrangement, an interlock sleeve is arranged longitudinally in the injector housing. Initially, the interlock sleeve is positioned so that operation of the firing mechanism is blocked by the interlock sleeve and so that a distal end of the interlock sleeve protrudes beyond the distal end of the injector housing. When the cap is removed and the device is pressed against the skin, the interlock sleeve contacts the patient's skin and is caused to move in the proximal direction with respect to the housing, which moves the interlock sleeve to a second position in which the firing mechanism is not blocked. In this way, the device can be operated only when the distal end of the device has been pressed against the patient's skin.

It is also known to provide a shrouding arrangement to conceal the needle as it is withdrawn from the injection site after injection, and to prevent contact with the needle after use of the device. For example, a tubular shroud component may be biased to advance distally out of the distal end of the housing as the device is withdrawn from the injection site, to keep the needle hidden. The shroud component is typically arranged to lock in position once fully deployed, to prevent accidental contact with the needle after use of the device.

By way of example, the present applicant's International Patent Application Publication No. WO 2015/087090 A2 describes an auto-injector device having an interlock arrangement, a viewing window and a needle shrouding arrangement.

The device described in WO 2015/087090 A2 also includes a means of adjusting the dosage of medicament delivered when the device is activated. The housing of the device includes a front part and a rear part that can be turned with respect to the front part along the longitudinal axis of the device from a first position, corresponding to a small dose, and a second position, corresponding to a large dose. The plunger of the device is coupled to turn with the rear housing part and includes a pair of guide pegs that engage with one of two pairs of tracks formed in the front housing part. When the housing parts are in the first position, the guide pegs align with a pair of tracks having a relatively short length, and when the housing parts are in the second position, the guide pegs align with a pair of tracks having a relatively long length. The stroke of the plunger is determined by the length of the guide tracks with which the pegs are aligned, so that either a small or a large dose is delivered when the device is activated depending on the relative position of the housing parts.

The provision of a dosage adjustment mechanism typically increases the complexity of the design of the auto-injector. For example, in the device described in WO 2015/087090 A2, to allow the plunger to turn with the rear housing part during dosage selection the firing mechanism includes an additional latch component to retain and release the drive spring and to transfer the load of the drive spring to the plunger. It is also necessary to provide a coupling rod to couple the plunger to the rear housing part. These factors increase the part count of the device, and the length of the device must be increased to accommodate the additional components.

Against this background, it would be desirable to provide improved medicament delivery devices that overcome or mitigate some of the above-described problems.

From a first aspect of the present invention, there is provided an injection device for delivery of a medicament from a container through a needle disposed at the distal end of the container, the device having an operating sequence for delivery of the medicament and comprising a housing for receiving the container, a drive mechanism arranged to apply an insertion force to the container upon activation of the drive mechanism, thereby to move the needle relative to the housing from a starting position to an insertion position, and an interlock member received in the housing and moveable with respect to the housing. The interlock member is movable from a first position in which activation of the drive mechanism is prevented to a second position in which the drive mechanism can be activated, and from the second position to a third position in which an opaque distal end region of the interlock member shrouds the needle when the needle is in the insertion position after injection of the medicament. The device further comprises a window to allow at least a part of the container to be viewed from outside the housing. The interlock member comprises a transparent region disposed between the container and the window during at least part of the operating sequence of the device.

In one example, the interlock member can be moved from the first position to the second position by pressing the device against an injection site. Thus the drive mechanism can only be activated to move the needle to the insertion position when the device is positioned correctly for use. The needle then pierces the injection site as it moves to the insertion position. After injection of the medicament, the device can be removed from the injection site, causing the interlock member to move from the second position to the third position, in which accidental contact with the needle is prevented by the distal end region of the interlock member.

By providing a transparent region of the interlock member, the container can be viewed through the window from outside the housing even if the interlock member is disposed between the container and the window, for example to allow the integrity of the container and the medicament to be checked before use of the device, or to provide a visual indication of the progress of the injection. However, because the distal end region of the interlock member is opaque, the needle is concealed from view as the device is removed from the injection site.

Accordingly, the inclusion of both a transparent region and an opaque distal end region allows the interlock member to perform the dual functions of preventing accidental operation of the device and shrouding the needle after use of the device without impairing the visibility of the container through the window. In this way, the design of the device can be simplified compared to prior art arrangements in which the interlock member must be arranged not to encroach between the container and a viewing window.

The interlock member may comprise an assembly including a distal end part and a body part. In this arrangement, the distal end part comprises the opaque distal end region and the body part comprises the transparent region. The whole of the distal end part may be opaque. For example, the distal end part may be formed of an opaque material. Similarly, the whole of the body part may be transparent. For example, the body part may be formed of a transparent material. The distal end part is preferably generally tubular.

The distal end part of the interlock member may be attached to the distal end of the body part by at least one clip formation. A guide arrangement may be provided to prevent rotation of the distal end part of the interlock member with respect to the body part. For example, the guide arrangement may comprise at least one recess in the body part or the distal end part for cooperation with a corresponding projection on the distal end part or the body part, respectively.

The distal end part of the interlock member may comprise a contact face for contact with the injection site in use, with an aperture in the contact face through which the needle extends when in the insertion position. The contact face is preferably enlarged with respect to the wall thickness of the distal end part of the interlock member. For example, the width of the aperture may be smaller than the internal width of the distal end part, to maximise the surface area of the contact face and to impair access to the needle when the interlock member is in the third position. The maximum width of the contact face is may be larger than the maximum internal width of the housing, again to maximise the surface area of the contact face. By maximising the surface area of the contact face, the pressure applied to the injection site in use of the device is reduced, resulting in improved comfort and reduced skin redness.

The transparent region of the interlock member may be disposed between the container and the window during the entire operating sequence of the device. For example, the transparent region of the interlock member may be a generally tubular sleeve part that surrounds the container. In another arrangement, the interlock member is movable in use such that the transparent region of the interlock member becomes disposed between the container and the window. For instance, the transparent region of the interlock member may move between the container and the window upon axial movement or turning movement of the interlock member during the operating sequence of the device. The window is preferably an aperture in the housing. The window could instead take the form of a gap between housing components or any other formation or feature that allows the container to be viewed from outside the housing.

The interlock member may be turnable with respect to the housing. In this case, the transparent region of the interlock member may be arranged such that the container remains visible through the window when the interlock member is turned with respect to the housing. In one example, the injection device comprises a dose setting mechanism for setting a quantity of medicament to be injected upon activation of the drive mechanism, and the dose setting mechanism comprises a dose selector that is turnable with respect to the housing to set the dose. The interlock member may be coupled to the dose selector for joint turning movement with respect to the housing. With such an arrangement, the container can remain visible through the window irrespective of the angular position of the interlock member with respect to the housing.

The interlock member may be biased in the distal direction with respect to the housing. The interlock member may be moveable against the bias from the first position to the second position when the distal end of the interlock member is pressed against an injection site in use of the device. Furthermore, the interlock member may be moveable from the second position to the third position under the influence of the bias when the device is removed from an injection site in use of the device. In this way, a single biasing means, such as a compression spring, can be utilised both to return the device to a locked state if the device is removed from the injection site without activation of the drive mechanism and to extend the interlock member to shroud the needle once an injection has been performed. This reduces the part count of the device compared to prior art arrangements in which a separate needle shroud and associated spring is provided.

The injection device may comprise locking means for locking the interlock member in the third position, thereby to prevent accidental contact with the needle after use of the device.

The drive mechanism may comprise a trigger component that is movable to a firing position to activate the drive mechanism. The drive mechanism may further comprise a drive element arranged to move in the distal direction to cooperate with the container and a latching member for latching the drive element in a starting position. The trigger component may comprise a latch release member for releasing the latching member upon movement of the trigger component to the firing position. The interlock member may be arranged to cooperate with the latching member to prevent release of the latching member when the interlock member is in the first position, and to permit release of the latching member when the interlock member is in the second position. In this way, when the interlock member is in the first position, accidental release of the latching member due to inadvertent movement of the trigger component can be prevented.

Alternatively, or in addition, the interlock member may cooperate with the trigger component to prevent movement of the trigger component to the firing position when the interlock member is in the first position and to allow movement of the trigger component to the firing position when the interlock component is in the second position.

The container may comprise a stopper for containing the medicament in the container, and the drive mechanism may comprise a plunger for cooperation with the stopper for delivery of the medicament. The container may be a syringe, such as a pre-filled syringe with a staked needle.

In a second aspect, the invention extends to an interlock member for an injection device according to the first aspect of the invention. The interlock member is arranged to cooperate with a drive mechanism of the device, and comprises a transparent region and an opaque distal end region.

Preferred and/or optional features of the first aspect of the invention may be used, alone or in appropriate combination, in the second aspect of the invention also.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which like reference numerals are used for like features, and in which:

Figure 1 is a schematic cross-sectional view of an injection device according to the present invention in a first state;

Figure 2 is a schematic cross-sectional view of the injection device of Figure 1 on a different plane;

Figure 3 is an exploded view of an interlock member of the injection device of Figure 1;

Figure 4 is a part-sectional isometric view of the interlock member of Figure 3;

Figure 5 is a schematic cross-sectional view of the injection device of Figure 1 in a second state;

Figure 6 is a schematic cross-sectional view of the injection device of Figure 1 in a third state; and

Figures 7(a), 7(b) and 7(c) are side views of the injection device of Figure 1 in the first, second and third states respectively.

Figures 1 and 2 show an injection device 100 according to an embodiment of the invention when in an initial state. Throughout the following description, the terms “front”, “distal” and related terms are used to refer to the end of the device 100 that is towards the patient’s skin in use (i.e. the lower end of the device in Figures 1 and 2), and the terms “rear”, “proximal” and related terms are used to refer to the end of the device 100 that is furthest from the skin in use (i.e. the upper end of the device 100 in Figures 1 and 2). Terms such as “turning” and “rotation” are intended to describe turning movement around the longitudinal axis of the device (i.e. the vertical axis in Figures 1 and 2), except if the context demands otherwise.

The device 100 includes an elongate two-part housing comprising a generally tubular front housing body 110 and a generally tubular rear housing body 140 rotatably attached to the proximal end of the front housing body 110. A trigger component in the form of a trigger button 200 is retained in the proximal end 142 of the rear housing body 140. The trigger button 200 forms part of a drive mechanism that also includes a drive element or plunger 300 and a drive spring 330 for driving the drive element 300 in the distal direction upon activation of the drive mechanism.

The front housing body 110 houses a medicament container, which in this case is a pre-filled syringe 10. The syringe 10 is preferably of a type known in the art, for example a Hypak syringe. The syringe 10 comprises a generally tubular glass barrel or body 12. At its distal end, the body 12 is formed into a reduced-diameter end portion 14 that carries a staked hypodermic needle 16. The body 12 is filled with a quantity of medicament 20 and is closed by a stopper 22 that is slidably received in the body 12. An outwardly-projecting flange 24 is provided at the proximal end of the body 12.

The syringe body 12 is received in a carrier assembly 220. The carrier assembly 220 comprises a generally tubular carrier support 222 that receives and supports an elastomeric insert or sleeve 224. The sleeve 224 defines a bore for receiving the syringe body 12 and the sleeve 224 is sized so as to grip against the syringe body 12 to create a frictional or interference fit. The sleeve 224 is made from a material with a suitably high coefficient of friction on the glass body 12, such as a thermoplastic elastomer.

The carrier assembly is guided for axial movement within the front housing body 110 by an interlock member 250, which is arranged concentrically around the carrier assembly 220. An interlock spring 221 acts to bias the carrier assembly 220 and the interlock member 250 apart.

The interlock member 250, which is shown in more detail in Figures 3 and 4, is of two-part construction and comprises an interlock body part 252, made from a transparent material, and a distal end part 254 made from an opaque material. The interlock body 252 and distal end part 254 are shown separately in Figure 3, and attached together in Figure 4.

The interlock body 252 comprises a generally tubular sleeve part 256 having an internal flange 257 that acts as a spring seat for the interlock spring 221. A pair of longitudinally-extending guide arms 258 extend proximally from the sleeve part 256 to connect to a ring part 260. In turn, a pair of interlock fingers 262 extend longitudinally and proximally from the ring part 260. Each interlock finger 262 has an aperture or cut-out 263 adjacent to its proximal end 265.

The distal end part 254 of the interlock member 250 is generally tubular, and is attachable to the interlock body 252 by way of a clipping engagement. To this end, a pair of ramped clip formations 264 are provided on the outer surface of the sleeve part 256 of the interlock body 252. Each of the clip formations 264 is positioned between two recesses or slots 266 in the sleeve part 256 that extend proximally from the distal end of the sleeve part 256. When assembled, the clip formations 264 on the sleeve part 256 are received in a pair of slots 268 formed in the wall of the distal end part 254, adjacent to its proximal end. To aid assembly, the distal end of the sleeve part 256 is chamfered on its outer edge, and the proximal end of the distal end part 254 is chamfered on its inner edge, and the longitudinally-extending slots 266 in the sleeve part 256 allow the clip formations 264 to bend inwardly as the distal end part 254 is pressed onto the end of the interlock body 252.

As shown most clearly in Figure 4, the inner surface of the distal end part 254 is provided with longitudinally-extending projections or ribs 270. The ribs 270 serve to stiffen the distal end part 254, and are positioned to extend into the longitudinally-extending slots 266 of the sleeve part 256. In this way, the ribs 270 and the slots 266 can cooperate to provide a guide arrangement for guiding the distal end part 254 into position during assembly of the device, and to prevent rotation of the distal end part 254 with respect to the interlock body 252 after assembly. A contact face 272 is disposed at the frontmost end of the distal end part 254 of the interlock member 250. The contact face 272 comprises an annular ring having a central aperture 274 that is of smaller diameter than the internal diameter of the remainder of the distal end part 254. The outer diameter of the contact face 272 is larger than the outer diameter of the remainder of the distal end part 254. In this way, the contact face 272 is enlarged compared to the wall thickness of the distal end part 254 to provide an increased surface area for contact with the injection site in use of the device, compared to a simple tube shape. As shown most clearly in Figure 4, the contact face 272 is provided with a plurality of projections or nibs 273 to help prevent the contact face 272 from slipping when placed on the skin.

Referring back to Figures 1 and 2, the interlock member 250 extends along substantially the whole length of the device 100. The carrier assembly 220 is guided by the guide arms 258 of the interlock body 252. The contact face 272 is disposed distally with respect to the distal end face 112 of the front housing body 110, and the interlock fingers 262 extend past the drive element 300 with the proximal ends 265 of the interlock fingers 262 disposed adjacent to the trigger button 200. The sleeve part 256 of the interlock body 252 is guided in the bore of a front portion 116 of the front housing body 110. To help centre the interlock member 250 along the axis of the device, an annular ramp formation 269 and a pair of arcuate, ramped guide ribs 271 are provided on the sleeve part 256 of the interlock body 252. The ramp formation 269 and the guide ribs 271 bear against the wall of the bore of the front housing body 110.

The drive element 300 comprises a plunger rod 304 and a can-shaped plunger body 306. The plunger body 306 is closed at its proximal end by an end plate 308 to which the plunger rod 304 is attached. The plunger body 306 extends distally from the end plate 308 to act as a guide for the drive spring 330. The plunger body 306 has an external flange that provides a spring seat 310 for the distal end of the drive spring 330. The proximal end of the drive spring 330 acts against an internal flange 144 of the rear housing body 140. Two arcuate slots (not shown) are formed in the end plate 308 to allow the interlock fingers 262 of the interlock member 250 to pass through the end plate 308 to extend towards the trigger button 200 (see Figure 1).

Two proximally-projecting latching arms 320, shown most clearly in Figure 1, are attached to the end plate 308 of the drive element 300. An inwardly-facing clip formation 322 is provided at the proximal end of each latching arm 320. Each clip formation 322 has a ramped proximal face and a distal face that is substantially perpendicular to the axis of the device 100.

When the device 100 is in the initial state, the latching arms 320 engage with a bridge part 148 of the rear housing body 140. The bridge part 148 extends across the bore of the rear housing body 140 and includes suitable cut-outs or openings to allow both the latching arms 320 of the drive element 300 and the interlock fingers 262 to pass through the bridge part 148.

The trigger button 200 comprises a button chassis 202. A pair of retaining arms 208, visible in Figure 2, extend distally from the chassis 202. Each retaining arm 208 is provided with an outwardly-facing clip formation at its distal end to engage with the flange 144 of the rear housing body 140, so as to retain the button 200 in engagement with the rear housing body 140. A pair of latch release pins 212, visible in Figure 1, also extend distally from the chassis 202. As will be explained in more detail below, the latch release pins 212 are arranged to cooperate with the clip formations 322 of the latching arms 320 of the drive element 300 to release the latching arms 320 when the trigger button 200 is moved distally with respect to the rear housing body 140. A proximal part 118 of the front housing body 110 serves as a guide for the axial movement of the drive element 300. To this end, the internal surface of the proximal part 118 is provided with a plurality of parallel elongate tracks or channels 126. As shown most clearly in Figure 1, a pair of plunger guide formations 316, in the form of longitudinally-extending ribs, are disposed diametrically opposite to one another on the rim 312 of the spring seat 310 of the drive element 300. The guide formations 316 are guided within the channels 126 in the front housing body 110 when the drive element 300 is released.

Each channel 126 has a different length to the adjacent channels 126. In this way, the distal ends 128 of each channel 126 provide stop formations for the drive element 300 at different axial positions relative to the distal end 112 of the front housing body 110, compared to the neighbouring channels 126. The channels 126 are arranged in pairs, with the channels 126 of each pair being diametrically opposite one another and having equal lengths. The channels 126 are arranged in order of increasing length, moving around the circumference of the front housing body 110.

In this way, the channels 126 form part of a dose setting mechanism of the device 100, with which the dosage of medicament to be delivered when the device 100 is activated can be set in advance by aligning the guide formations 316 of the drive element 300 with the appropriate pair of channels 126. The stroke of the drive element 300, and therefore the quantity of medicament delivered, is determined by the length of the selected pair of channels 126.

The rear housing body 140 acts as a dose selector for the device 100. To set the desired dose, the rear housing body 140 is turned with respect to the front housing body 110 about the longitudinal axis of the device 100. The drive element 300, the trigger button 200 and the interlock member 250 are all coupled to the rear housing body 140, and therefore turn along with the rear housing body 140 with respect to the front housing body 110. In this way, the guide formations 316 of the plunger can be brought into alignment with the desired pair of tracks 126. Suitable indicator means can be provided on the front and rear housing bodies 110, 140 or elsewhere to provide an indication of the dose that has been set.

As shown in Figure 2, the front housing body 110 includes a window 114 for viewing of the syringe 10. Because the material of the interlock body 252 is transparent, the syringe 10 is visible through the window 114 even though the sleeve part 256 of the interlock body 252 surrounds the syringe body 12 and is therefore disposed between the syringe 10 and the window 114.

The device 100 is supplied with a needle shield (not shown) attached to the collar 14 of the syringe 10, to maintain the sterility of the needle 16 and to prevent leakage of medicament 20 during transport and storage of the device 100. The shield may be of the type known in the art as a rigid needle shield. The device 100 is also supplied with a deshielder cap (not shown) arranged to fit over the tapered distal portion 116 of the front housing body 110 to close the distal end of the device 100.

An operating sequence of the device 100 will now be described.

Before use of the device, the integrity of the syringe and the condition of the device can be checked by a user by insepection through the window 114. Once it has been verified that the device is ready for use, the deshielder cap can be grasped and removed from the front housing body 110, which also causes removal of the rigid needle shield from the needle 16. Before or after removal of the cap, the rear housing body 140 can be rotated with respect to the front housing body 110 to set the desired dose for injection.

Figures 1, 2 and 7(a) show the device 100 in the initial state, with the deshielder cap and rigid needle shield removed. In this initial state, the needle 16 of the syringe 10 is in a starting position, with the needle 16 retracted proximally with respect to the distal end of the device 100 and thus shrouded within the front housing body 110.

Referring in particular to Figures 1 and 2, with the device in its initial state, the interlock spring 221 biases the interlock member 250 in the distal direction, so that part of the distal end part 254 of the interlock member 250 protrudes from the distal end of the device 100. As shown most clearly in Figure 2, distal movement of the interlock member 250 beyond a certain point is limited by the engagement of the annular ramp formation 269 on the sleeve part 256 of the interlock body 252 with a pair of ramped support tabs 125 provided inside the front housing body 110. In this way, the interlock member 250 is maintained in a first position.

Referring back to Figure 1, with the interlock member 250 in the first position, the proximal ends 265 of the interlock fingers 262 are positioned between the respective latching arms 320 and the internal flange 144 of the rear housing body 140. In this way, the proximal ends 265 of the interlock fingers 262 prevent the latching arms 320 from flexing outwardly to allow the clip formations 322 to disengage from the bridge part 148. Thus, with the interlock member 250 in the first position, operation of the trigger button 200 does not cause release of the drive element 300.

In the next part of the operating sequence, the distal end of the device 100 is pressed against the injection site, so that the contact face 272 of the distal end part 254 of the interlock member 250 contacts the skin. As shown in Figures 5 and 7(b), the pressure thus applied to the contact face 272 causes the interlock member 250 to move proximally with respect to the front and rear housing bodies 110, 140, towards the trigger button 200 and against the bias of the interlock spring 221. The interlock member 250 thus moves into a second position, in which the contact face 272 of the distal end part 254 of the interlock member 250 abuts the distal end 112 of the front housing body 110.

As shown in Figure 5, movement of the interlock member 250 in the proximal direction causes the cut-outs 263 adjacent to the proximal ends 265 of the interlock fingers 262 to move into register with the latching arms 320. Thus, with the interlock member 250 in the second position, the interlock fingers 262 no longer block movement of the latching arms 320.

Instead, when the trigger button 200 is moved distally, the latch release pins 212 cooperate with the clip formations 322 to flex the latching arms 320 outwardly, into the spaces provided by the cut-outs 263, so that the clip formations 322 disengage from the bridge part 148 of the rear housing body 140. This releases the drive element 300 to move in the distal direction under the influence of the drive spring 330. Thus movement of the interlock member 250 from the first position to the second position has the effect of unlocking the drive mechanism of the device 100. If the device 100 is removed from the skin before the trigger button 200 is pressed, the interlock spring 221 urges the interlock member 250 back into its first position to lock the drive mechanism once more.

After the trigger button 200 has been operated to disengage the latching arms 320 from the rear housing body 140, the drive spring 330 urges the drive element 300 to move distally to engage with the syringe 10. In particular, the plunger rod 304 of the drive element 300 contacts the stopper 22 of the syringe 10 and initially, as a result of the friction between the stopper 22 and the syringe body 12 and the fluid flow resistance through the needle 16, the syringe body 12 moves together with the stopper 22 and the carrier assembly 220 to displace the syringe body 12 distally from its starting position to begin an insertion stroke of the syringe 10. During the insertion stroke, the interlock spring 221 is compressed and the syringe 10 moves distally to advance the needle 16 into an insertion position in which the needle 16 extends out of the distal end of the device 100, through the aperture 274 in the contact face 272, to pierce the injection site.

Distal movement of the syringe body 12 stops when the carrier assembly 220 engages with the ring part 260 of the interlock body 252, with the needle 16 in the insertion position. After the end of the insertion stroke, continued movement of the drive element 300 in the distal direction causes the plunger rod 304 to displace the stopper 22 with respect to the syringe body 12, forcing the medicament 20 through the needle 16 and into the injection site in a delivery stroke of the device 100.

Distal movement of the drive element 300 stops when the guide formations 316 of the drive element 300 reach the distal ends of the respective guide channels 126 in the front housing body 110. At this point, the delivery stroke ends and ejection of the medicament ceases.

The syringe 10 remains visible through the window 114, by virtue of the transparent interlock body 252. The stopper 22 and the plunger rod 304 may become visible through the window 114 as the injection progresses. The end of the injection may be indicated visually and/or audibly, for example by the use of a feedback component (not shown) that appears in the window at the end of the plunger stroke.

After distal movement of the drive element 300 ceases, the device 100 can be removed from the injection site to withdraw the needle 16 from the skin. As the device 100 is pulled away from the skin, the interlock spring 221 acts to move the interlock member 250 distally with respect to the front housing body 110, causing the distal end part 254 of the interlock member 250 to advance out of the distal end 112 of the front housing body 110 during withdrawal, keeping the contact face 272 in contact with the skin. Because the distal end part 254 is opaque, the needle 16 is concealed from the patient’s view as it is withdrawn from the skin.

Distal movement of the interlock member 250 relative to the front housing body 110 continues until the ring part 260 of the interlock component 250 contacts a pair of support arms 122 formed in the front housing body 110, as shown in Figure 6. The interlock component 250 is now in a third position with respect to the front housing body 110.

Figures 6 and 7(c) show the device 100 after the injection has been completed and the device 100 has been completely removed from the injection site. The needle 16 is still in the insertion position, so that the tip of the needle projects beyond the distal end 112 of the front housing body 110. Flowever, with the interlock component 250 in the third position, the distal end part 254 of the interlock component 250 shrouds the needle 16 (i.e. the contact face 272 of the distal end part 254 is disposed distally with respect to the tip of the needle 16). Thus the distal end part 254 of the interlock component 250 serves to prevent accidental contact with the needle 16 after use of the device 100.

As the interlock component 250 moves into the third position, the annular ramp formation 269 on the sleeve part 256 of the interlock body 252 moves distally past the support tabs 125 (see Figure 2, not shown in Figure 5). The ramp formation 269 and tabs 125 are shaped so as to block movement of the interlock component 250 back in the proximal direction, thus locking the interlock component 250 in the third position and avoiding subsequent exposure of the needle 16. The device 100 can then be disposed of.

With the interlock component 250 in the third position, the syringe 10 is still visible through the window 114, through the transparent material of the interlock body 252. The used condition of the device 100 can thus be readily identified by the presence of the stopper 22 at or near the distal end of the syringe body 12. The distal end of the plunger rod 304 may also be visible through the window 114. Conveniently, the stopper 22 and/or part of the plunger rod 304 could be coloured or otherwise highlighted to help provide an easily visible end-of-dose indication.

During assembly of the device 100, the interlock body 252 can be inserted into the front housing body 110 from the proximal end. The distal end part 254 can then be attached to the distal end of the interlock body 252 by inserting the distal end part 254 into the distal end of the front housing body 110. Because the contact face 272 of the distal end part 254 does not need to pass through the inside of the front housing body 110, the outer diameter of the contact face 272 (or the width of the contact face 272, in cases where the device is not circular in cross section) can be larger than the internal diameter (or width) of the front housing body 110. Accordingly, the contact face 272 can have an increased outer diameter or width compared with a one-piece interlock member.

Similarly, in a two-piece interlock member assembly, the diameter of the aperture 274 in the contact face 272 can be smaller than the internal diameter of the distal end part 254. Such an arrangement would not practical with a one-piece interlock member, due to difficulties of manufacturing a part having a restricted diameter aperture at its distal end along with an internal flange 257.

For these reasons, the surface area of the contact face 272 is larger than would be possible if the distal end part 254 were integrally formed with the interlock body 252 in a one-piece interlock member. Accordingly, when the distal end of the device 100 is pressed against the skin to move the interlock member 250 from the first position to the second position, the increased surface area of the contact face 272 reduces the local pressure on the skin at the injection site, reducing discomfort during the injection and reducing redness of the skin due to the contact pressure.

It will also be appreciated that the reduced diameter aperture 274 in the contact face 272 makes it more difficult to touch the needle 16 through the aperture 274 both in the initial and final states of the device.

In the illustrated embodiment, the whole of the interlock body 252 is transparent (i.e. the transparent region of the interlock member 250 comprises the entirety of the interlock body 252). This means that the syringe 10 remains visible through the window 114 irrespective of the axial position or angular orientation of the interlock member 250 in use of the device 100. This arrangement means that the rear housing body 140 can be turnable through a relatively large angle for dose selection without obscuring the view of the syringe 10 through the window 114, allowing a large number of different dosage options to be provided by the device.

In other embodiments of the invention, only a part of the interlock body may be transparent, and the benefits of the invention will be realised provided that the transparent region of the interlock member is disposed between the syringe and the window during at least a part of the operating sequence of the device. The transparent region may extend around the whole circumference of the interlock body, or around only a part of the circumference as appropriate for a particular application. The interlock body may itself be an assembly of two or more body components, with at least one of the components being transparent. In one variant, the sleeve part of the interlock body is formed as a first body component made from a transparent material, while the guide arms, the ring part and the interlock fingers may be formed as a second body component made from a non-transparent material. The body components may be connected to one another by any suitable means, including by way of a clipping engagement or by adhesive or welds.

It is also conceivable that the interlock member could be of single-part construction, with an opaque distal end region and a transparent region. For example, the interlock member could be formed as a single part from a transparent material, and the distal end region of the interlock member could be made opaque, for example by painting, printing, coating or by affixing an opaque film to the distal end region.

It will be appreciated that the transparent region of the interlock member need not be perfectly transparent, provided that the transparent region is sufficiently see-through to allow the container and its contents to be seen in suitable detail through the window. Similarly, the distal end part of the interlock member need only be sufficiently opaque to prevent the needle from being clearly seen through the material of the distal end part during normal use of the device.

The transparent region of the interlock member may be disposed between the syringe and the window at all times during the operating sequence of the device, as is the case for the above-described embodiment. However, it is also possible that the transparent region of the interlock member could move into position between the syringe and the window during operation of the device. For example, in a variant of the illustrated device, the sleeve part of the interlock body is not a complete tube, but instead comprises one or more gaps. In the initial state of the device, before the dosage has been set, a gap in the sleeve part may be aligned with the window, so that the syringe can be seen through the window and the gap in the sleeve part. When the interlock member turns during dose setting, the gap may move away from the window, bringing a transparent region of the sleeve part between the syringe and the window to maintain visibility of the syringe through the window and the sleeve part.

As noted above, the device may include an additional feedback component to provide a visual indication of the end of the dose. The feedback component may be in the form of an annular ring that is disposed around the interlock member, between the interlock member and the front housing body. In the initial state of the device, the feedback component is latched in a proximal position with respect to the window in the front housing body, so that it cannot be seen. When the plunger reaches the end of the delivery stroke, the feedback component is unlatched and moves distally to become visible through the window. In such cases, the feedback component may obscure the syringe at the end of medicament delivery.

It will be appreciated that the use of an interlock member having a transparent region and an opaque distal end region is not limited to a device of the type described with reference to Figures 1 and 2. For example, an interlock member of this type could be used in an injector or auto-injector device having alternative arrangements for locking the injector mechanism, selecting the dose, releasing the plunger and so on. The interlock member could be used in devices that provide additional functionality, such as automatically priming the syringe or medicament container before injection.

In the illustrated embodiment, the interlock member prevents accidental operation of the device by preventing unlatching of the latching arms of the plunger until the interlock member has moved to the second position. However, alternative or additional mechanisms for preventing accidental operation or undesirable movement of parts as the device is prepared for use could be present. For example, the interlock member may be arranged to block movement of the trigger button into a firing position until the interlock member has moved to the second position. Movement of the interlock member from the first position to the second position could cause movement of the trigger button from a stowed position, in which the button cannot be operated, to a working position in which the button can be pressed. The interlock member may also be used to lock the carrier assembly in position with respect to the housing when the interlock member is in the first position, to prevent movement of the syringe until the interlock member has been moved to the second position.

The application of the invention is not limited to devices having a pre-filled syringe with a staked needle. Instead, other medicament containers could be used, such as a cartridge or vial with an attachable needle.

As will be apparent to the skilled person, many further variations and modifications of the devices and features described above are possible without departing from the scope of the invention as defined in the appended claims.

Claims

1. An injection device (100) for delivery of a medicament from a container (12) through a needle (16) disposed at the distal end of the container (12), the device having an operating sequence for delivery of the medicament and comprising: a housing (110) for receiving the container (12); a drive mechanism (200, 300, 330) arranged to apply an insertion force to the container (12) upon activation of the drive mechanism (200, 300, 330) thereby to move the needle (16) relative to the housing (110) from a starting position to an insertion position; an interlock member (250) received in the housing (110) and moveable with respect to the housing (110) from a first position in which activation of the drive mechanism (200, 300, 330) is prevented to a second position in which the drive mechanism (200, 300, 330) can be activated, and from the second position to a third position in which an opaque distal end region (254) of the interlock member (250) shrouds the needle (16) when the needle (16) is in the insertion position after injection of the medicament; and a window (114) to allow at least a part of the container (12) to be viewed from outside the housing (110); wherein the interlock member (250) comprises a transparent region (252) disposed between the container (12) and the window (114) during at least part of the operating sequence of the device.

2. An injection device according to Claim 1, wherein the interlock member (250) comprises an assembly including a distal end part (254) and a body part (252), wherein the distal end part (254) comprises the opaque distal end region and wherein the body part (252) comprises the transparent region.

3. An injection device according to Claim 2, wherein the distal end part (254) is formed of an opaque material and wherein the body part (252) is formed of a transparent material.

4. An injection device according to Claim 2 or Claim 3, wherein the distal end part (254) of the interlock member (250) is attached to the distal end of the body part (252) by at least one clip formation (264, 268).

5. An injection device according to any of Claims 2 to 4, comprising a guide arrangement to prevent rotation of the distal end part (254) of the interlock member (250) with respect to the body part (252).

6. An injection device according to any of Claims 2 to 5, wherein the distal end part (254) of the interlock member (250) comprises a contact face (272) for contact with an injection site in use, and an aperture (274) in the contact face (272) through which the needle (16) extends when in the insertion position.

7. An injection device according to Claim 6, wherein the width of the aperture is smaller than the internal width of the distal end part (254).

8. An injection device according to any of Claims 6 to 8, wherein the maximum width of the contact face (272) is larger than the maximum internal width of the housing (110).

9. An injection device according to any preceding claim, wherein the transparent region (252) of the interlock member (250) is disposed between the container (12) and the window (114) during the entire operating sequence of the device.

10. An injection device according to any of Claims 1 to 8, wherein the interlock member (250) is movable in use such that the transparent region (252) of the interlock member (250) becomes disposed between the container (12) and the window (114) during a part of the operating sequence of the device.

11. An injection device according to any preceding claim, wherein the window (114) comprises an aperture in the housing (110).

12. An injection device according to any preceding claim, wherein the interlock member (250) is turnable with respect to the housing (110).

13. An injection device according to Claim 12, wherein the transparent region (252) of the interlock member (250) is arranged such that the container (12) remains visible through the window (114) when the interlock member (250) is turned with respect to the housing (110).

14. An injection device according to Claim 12 or Claim 13, comprising a dose setting mechanism for setting a quantity of medicament to be injected upon activation of the drive mechanism (200, 300, 330), wherein the dose setting mechanism comprises a dose selector (140) that is turnable with respect to the housing (110) to set the dose, and wherein the interlock member (250) is coupled to the dose selector (140) for joint turning movement with respect to the housing (110).

15. An injection device according to any preceding claim, wherein the interlock member (250) is biased in the distal direction with respect to the housing (110).

16. An injection device according to Claim 15, wherein the interlock member (250) is moveable against the bias from the first position to the second position when the distal end of the interlock member (250) is pressed against an injection site in use of the device.

17. An injection device according to Claim 15 or Claim 16, wherein the interlock member (250) is moveable from the second position to the third position under the influence of the bias when the device is removed from an injection site in use of the device.

18. An injection device according to any preceding claim, comprising locking means (269, 125) for locking the interlock member (250) in the third position.

19. An injection device according to any preceding claim, wherein the drive mechanism comprises a trigger component (200) that is movable to a firing position to activate the drive mechanism.

20. An injection device according to Claim 19, wherein the drive mechanism comprises a drive element (300) arranged to move in the distal direction to cooperate with the container (12) and a latching member (320) for latching the drive element (300) in a starting position, and wherein the trigger component (200) comprises a latch release member (212) for releasing the latching member (320) upon movement of the trigger component (200) to the firing position.

21. An injection device according to Claim 20, wherein the interlock member (250) is arranged to cooperate with the latching member (320) to prevent release of the latching member (320) when the interlock member (250) is in the first position, and to permit release of the latching member (320) when the interlock member (250) is in the second position.

22. An injection device according to any preceding claim, wherein the container (12) comprises a stopper (22) for containing the medicament in the container (12), and wherein the drive mechanism comprises a plunger (304) for cooperation with the stopper (22) for delivery of the medicament.

23. An interlock member (250) for an injection device according to any preceding claim, the interlock member (250) being arranged to cooperate with a drive mechanism (200, 300, 330) of the device and comprising: a transparent region (252); and an opaque distal end region (254).