HK1161563A - Medicament delivery devices - Google Patents

Description

Drug delivery device

Technical Field

The present invention relates to a drug delivery device for delivering a drug into a human or animal body, and in particular to an electronically controlled auto-injector having a replaceable cartridge. The device is typically used by a diabetic to whom insulin is to be administered.

Background

Drug delivery devices are commonly used by persons who are not receiving formal medical training, i.e. patients who are increasingly common for self-treatment of their conditions. These circumstances create a number of needs for such drug delivery devices. The syringe should be robust in construction yet easy to use in terms of its handling by the user and the handling of the parts. For diabetics, many users may be visually impaired and may also be physically infirm. Thus, it may prove difficult to use a device that is too large or too difficult to operate, especially for people with reduced dexterity.

U.S. patent specification 5,989,221 describes an electronically controlled injection device in which the preparation of the device for administration and subsequent delivery of the drug therefrom is controlled by electronic control means. In particular, the control means comprise position or attitude sensors for transmitting signals, whereby the preparation of the device cannot be performed unless the longitudinal axis of the injection cartridge is in a preset direction. This is the case when air is removed or a pharmaceutical composition is mixed. The control means is also operable for driving the piston rod a preset distance for delivering a dose of medicament.

In the described prior art devices, the user still needs to prime the device after the cartridge has been set. Furthermore, the device may suffer from underdosing, particularly when the cartridge is not properly positioned within the device after insertion by the user.

It is an object of the present invention to provide a drug delivery device wherein the replacement of the cartridge is easy for the user.

Disclosure of Invention

According to the present invention, there is provided a drug delivery device for delivering a drug to a patient, wherein the drug delivery device comprises: a housing; a retaining portion within the housing for receiving the cartridge; a piston rod for driving a bung of a cartridge; a drive mechanism comprising a motor for providing an output drive force to the piston rod for delivering the drug; and control means for controlling the operation of the device; the method is characterized in that:

providing a stopper sensor for sensing when the plunger rod is in contact with the stopper;

wherein the control means is operable for pushing the drive force of the piston rod to the bung.

In a preferred embodiment, the control means is operable for advancing the driving force of the piston rod until the bung sensor senses that the piston rod is in contact with the bung. A detent sensor may be provided for sensing the position of the retaining portion as it moves from the open position to the closed position. In this case, the control means may be operated for advancing the driving force of the piston rod only when the catch sensor senses that the holding part is in the closed position.

Furthermore, a cartridge sensor may be provided for sensing the presence of the cartridge in the holding portion. In this embodiment the control means is operable for advancing the drive force of the piston rod when the cartridge sensor senses that the cartridge is present and the catch sensor senses that the holding part is in the closed position.

a) When the stopper sensor senses that the plunger rod is in contact with the stopper; or b) the control means may be operated to prevent further advancement of the piston rod when, after initial contact between the piston rod and the bung, the cartridge has been moved to a fixed position within the housing. In this case, the force required to activate the bung sensor is greater than the sliding friction between the cartridge and the retaining part. The holding portion may comprise a door (door) of the drug delivery device. The control means may be operable to advance the piston rod driving force to deliver a dose of medicament when the cartridge sensor senses that the cartridge is in a preset (i.e. 'correct' or 'fixed') position relative to the retaining portion.

In an alternative embodiment, the detent sensor and the bung sensor may each generate a combined sensor signal, whereby the combined signal transmitted to the control means indicates that the cartridge is present and/or in the correct position when the piston rod contacts the cartridge bung.

In another embodiment, the control means is operable to reverse (rewind) the plunger rod a predetermined amount when the stopper sensor senses that the plunger rod is in contact with the stopper. This is advantageous in situations where the plug sensor is in the form of a dome switch or other pressure switch (including solid state switches and pressure switches), thereby placing the dome switch in an open position. For drug delivery, the control means drives the piston rod by an amount that counteracts this reversal.

Any or all of the cartridge, detent and bung sensors may be switches that conduct signals from their respective sensing functions to the control means.

An advantage of an embodiment of the present invention is that the drug delivery device automatically pushes the piston rod to the cartridge bung when the cartridge is present and the door/holding portion of the injector is closed. This simplifies the number of operations for the user, including avoiding the need for the user to push the piston rod against the bung by controlling the (dial) air-shot dose. Battery life is conserved by avoiding the driving force of the piston rod when no cartridge is present. Another advantage is that the possibility of underdosing after insertion of a new or used cartridge is reduced, since the cartridge is properly or completely seated in the retaining portion.

The term "drug delivery device" according to instant invention shall mean a single-dose or multi-dose or pre-set dose or predefined, disposable or reusable device designed to dispense a user selectable or predefined dose of a medical product, preferably a plurality of predefined doses of a medical product, such as insulin, growth hormone, low molecular weight heparin, and analogues and/or derivatives thereof, and the like. The device may be of any shape, for example compact or pen-type. Dose delivery may be achieved by a mechanical (optionally manual) or electrical drive mechanism or a stored energy drive mechanism such as a spring or the like. Dose selection may be achieved by a manual mechanism or an electronic mechanism. Additionally, the device may include components designed to monitor physiological characteristics such as blood glucose levels, etc. Further, the device may or may not include a needle. In particular, the term "drug delivery device" may refer to a needle-based device with an electrical drive mechanism providing multiple doses, which device is designed to be used by persons without formal medical training, such as patients. Preferably, the drug delivery device is of an automatic type, i.e. an auto-injector.

The term "housing" according to instant invention preferably refers to any outer housing ("main housing", "body", "outer housing") or inner housing ("insert", "inner body") having a unidirectional axial coupling to prevent proximal movement of the particular assembly. The housing may be designed such that the drug delivery device or any mechanism thereof can be safely, correctly and comfortably handled. Generally, the housing is designed to house, secure, protect, guide and/or engage any internal components of the drug delivery device (e.g., drive mechanism, cartridge, plunger, piston rod) by limiting exposure to contaminants such as liquid, dust, dirt, etc. Generally, the housing may be tubular or non-tubular, unitary or a multi-part assembly. Typically, the outer housing is used to house a cartridge from which a dose of a medicinal product may be dispensed.

The term "engine" according to instant invention preferably refers to any motorized device for driving a gear system and ultimately an input drive means. In the present invention, a stepper motor is preferably employed, although any means for driving the gear system or drive means, including mechanical or manual actuation means, may be incorporated into the device.

The "proximal end" of a device or device assembly refers to the end furthest from the dispensing end of the device.

The "distal end" of a device or device assembly refers to the end closest to the dispensing end of the device.

Devices embodying the present invention may generally employ reusable drug delivery devices that include replaceable cartridges and may also be used within the context of autoinjector devices.

Drawings

The invention will be further described, by way of example, with reference to the accompanying drawings, in which like references indicate similar elements:

FIG. 1 is a front view of a drug delivery device that may include an embodiment of the present invention;

fig. 2 is a front view of the drug delivery device of fig. 1 with a cartridge door shown in an open position for receiving a cartridge;

FIG. 3 is a perspective view of a cartridge sensor/switch;

FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3;

FIG. 5 is a perspective view of a stopper sensor/switch; and is

Fig. 6 is a perspective view of the drug delivery device of fig. 2 showing a door or retaining portion of a sensor/switch.

Detailed Description

In fig. 1, the drug delivery device 1 comprises a housing 2 with a display 3 for displaying functional operations regarding the operation of the drug delivery device, said information comprising a set dose, the number of doses remaining in the cartridge. User interface buttons 4, 5 and 6 are provided to allow a user to operate the injector, including priming, setting a dose, opening the cartridge retaining portion and the door 7 and starting to dispense the set dose. A threaded needle attachment 8 is provided so that the needle can be attached for dose delivery and subsequently removed and discarded. A cover (not shown) may be provided to cooperate with the lower portion of the housing 2 to assist in protecting the device from particles and liquids. Fig. 2 shows the drug delivery device 1 with the cartridge holding portion and the door 7 in an open position for receiving a replaceable cartridge 9.

Fig. 3 shows the cartridge holding part and the door 7 in more detail, where the cartridge 9 is arranged. The retaining portion 7 is axially fixed to the housing 2 by means of a link 11, whereby the retaining portion 7 is movable between an open position (see fig. 2) and a closed position (see fig. 1). The arm 13 extends to the housing 2 and has a stop 15 to limit the outward extension of the door/retaining portion 7 in the direction of arrow B. The stop 15 may also engage a latch switch or sensor 16, as shown in fig. 6, which sensor 16 is provided to sense when the retaining portion 7 is moved from the open or closed position. An actuator/lever 17 is provided to sense the presence of the cartridge 9 within the housing 2 and the closure of the retaining portion 7. Fig. 4 is a cross-sectional view taken along line a-a of fig. 3 and shows the cartridge 9 and the driver/lever 17. In this embodiment, the lever 17 forms part of a contact switch 19 with a replaceable contact 21. The replaceable contact 21 is movable to change the state of the switch 19 when the cartridge is received in the holding portion 7. The lever 17, the contact switch 19 and the replaceable contact 21 together form a cartridge sensor.

Fig. 5 is a perspective view of the telescoping piston rod assembly 23, which includes slidable assemblies 25 and 27 telescoping within a housing 29. The assembly 23 is provided at its end with a dome switch 31 which contacts the bung 20 of the medicament cartridge 9. The dome switch 31 is connected to a flexible PCB element 33 that extends within the assemblies 25 and 27. The element 33 starts at the other end of the assembly 23, passes through the housing 29 to terminate at a contact 35. The contact 35 is connected to control means (not shown) operable to control the device, including the drive piston rod.

Fig. 6 is a perspective view of the drug delivery device of fig. 2 and shows the approximate positions of the detent switch or sensor 16 and stop 15 within the device. Although shown as a contact switch, it should be understood that the latch switch or sensor may alternatively be a mechanical latch or any other switch or sensor known in the art.

The operation of the drug delivery device 1 is as follows. The detent sensor 16 may be provided to sense when the retaining portion 7 is moved from the open or closed position and the stopper sensor 31 may be operated to sense when the piston rod 25, 27 is in contact with the stopper 20. The control means is operable to push the driving force of the piston rods 25, 27 to the stopper 20, provided that the latch sensor 16 senses that the holding part 7 has moved to the closed position. The control means may be operated to advance the driving force of the piston rods 25, 27 until the stopper sensor 31 senses that the piston rods are in contact with the stopper 20.

Cartridge sensors 17, 19, 21 are provided to sense the presence of the cartridge 9 in the holding portion 7. In this case, the control means is operable to advance the driving force of the piston rods 25, 27 when the cartridge sensor 17, 19, 21 senses the presence of a cartridge and the catch sensor 16 senses that the holding part 7 has moved from the open position to the closed position.

It may also be beneficial for the cartridge sensors 17, 19, 21 to operate only after the catch sensor 16 detects whether the holding part 7 has been opened or closed. It is not necessary to monitor the cartridge sensor when the retaining portion is not in the closed position. This may increase the battery life of the device.

In this case, the holding part 7 (without cartridge) can be opened to the position shown in fig. 2 in order to load the cartridge 9 into the device 1. The movement of the holding part 7 from the closed position to the open position is detected by means of a click sensor 16. The signal from the catch sensor 16 causes the control means to monitor the cartridge sensors 17, 19, 21 to determine whether the cartridge 9 is present. In this case, no cartridge is present, and thus no signal is detected. Therefore, the control means cannot advance the driving force of the piston rods 25, 27. This also contributes to battery life.

The cartridge 9 can then be placed in the holding portion 7 and the holding portion closed. With the holding portion 7 closed, the movement of the holding portion is detected by the latch switch 16, causing the control means to monitor the cartridge sensors 17, 19, 21. When the cartridge 9 is present in the holding part 7 and the holding part is closed, the replaceable contact 21 is in contact with the switch 19, indicating the presence of the cartridge. The control means is operable to advance the driving force of the piston rods 25, 27 when both the catch sensor 16 and the cartridge sensors 17, 19, 21 sense that the holding portion 7 is closed and the cartridge 9 is present.

a) When the stopper sensor 31 senses that the plunger rod is in contact with the stopper 20; or b) the control means may be operated to prevent further advancement of the piston rod 25, 27 when, after initial contact between the piston rod and the bung, the cartridge 9 has been moved to a fixed position within the retaining portion (see fig. 3). In this case, the force required to actuate the bung sensor 31 is greater than the sliding friction between the cartridge 9 and the retaining part 7. The holding portion 7 may comprise a door of the drug delivery device 1. When the cartridge sensor 17, 19, 21 senses that the cartridge 9 is in a preset (i.e. 'correct' or 'fixed') position relative to the holding portion, the control means is operable to advance the piston rod driving force to deliver a dose of medicament.

In an alternative embodiment, the click sensor 16 and the bung sensor 31 may each generate a combined sensor signal, whereby the combined signal transmitted to the control means indicates that the cartridge 9 or the holding part 7 is present and/or in the correct position when the piston rod 25, 27 contacts the cartridge bung 20.

Since the bung sensor 31 is in the form of a dome switch, the control means is operable to reverse the piston rods 25, 27 by a preset amount when the bung sensor 31 senses that the piston rods are in contact with the bung 20.

Claims (10)

1. A drug delivery device for delivering a drug to a patient, wherein the drug delivery device comprises: a housing; a retaining portion within the housing for receiving the cartridge; a piston rod for driving a bung of a cartridge; a drive mechanism comprising a motor for providing an output drive force to the piston rod for delivering the drug; and control means for controlling the operation of the device; the method is characterized in that:

providing a stopper sensor for sensing when the plunger rod is in contact with the stopper;

wherein the control means is operable for pushing the drive force of the piston rod to the bung.

2. A medicament delivery device according to claim 1, wherein the control means is operable for advancing the driving force of the piston rod until the bung sensor senses that the piston rod is in contact with the bung.

3. A drug delivery device according to claim 1 or 2, comprising a click sensor for sensing the position of the holding part when the holding part is moved from the open position to the closed position or from the closed position to the open position.

4. A drug delivery device according to claim 3, wherein the control means is operable for advancing the driving force of the piston rod when the click sensor senses that the holding part is in the preset position or the closed position.

5. A drug delivery device according to any of the preceding claims, comprising a cartridge sensor for sensing the presence of a cartridge in the holding portion.

6. A drug delivery device according to claim 5, wherein the control means is operable for advancing the driving force of the piston rod when the cartridge sensor senses the presence of a cartridge and the catch sensor senses that the holding part is in the closed position.

7. The drug delivery device according to any of the preceding claims, wherein a) when the stopper sensor senses that the piston rod is in contact with the stopper; or b) the control means may be operated to prevent further advancement of the piston rod when, after initial contact between the piston rod and the bung, the cartridge has been moved to a fixed position within the housing.

8. A drug delivery device according to any of claims 3 to 7, wherein the click sensor and the bung sensor each generate a combined sensor signal, whereby the combined signal transmitted to the control means indicates that the cartridge is present and/or in the correct position when the piston rod contacts the cartridge bung.

9. The drug delivery device of any preceding claim, wherein the housing comprises a receptacle for a user replaceable cartridge.

10. An autoinjector comprising a drug delivery device according to any one of the preceding claims.