Autoinjector with anti-activation feature

Abstract

An autoinjector comprises: a main housing for receiving a syringe or cartridge; the driving mechanism is positioned in the main shell; and a shield coupled to the front end of the main housing and movable relative to the housing between an extended position in which the needle tip is substantially shielded and a retracted position in which the needle tip may extend through an opening in the shield. The shroud is coupled to the drive mechanism such that movement of the shroud causes release of the drive mechanism and the shroud is biased toward the extended position. The device cap and the shroud include respective substantially non-flexible configurations that, when the cap is attached to the housing, are directly mechanically engageable with each other to prevent or limit inward movement of the shroud relative to the housing.

Description

Technical Field

[0001] The present invention relates to an autoinjector for drug delivery and provided with an anti-activation feature to prevent or reduce the risk of accidental activation. Background Art

[0002] Mechanically powered auto-injectors are commonly used to deliver many different types of medications. In most injectors, the force to deliver the injection is provided by a powerful coil spring that is compressed and released to provide the delivery force or expanded and contracted to provide the force. In some cases, the same or a different spring mechanism provides the needle insertion force to force the syringe or cartridge needle tip to penetrate the user's skin prior to drug delivery.

[0003] WO2022 / 179832 and WO2020 / 064927 describe auto-injectors suitable for use with safety syringes, for example, as described in WO2019 / 086718. These auto-injectors include a base portion for receiving the safety syringe and a cover portion that can be hingedly connected to the base portion. The action of opening and closing the cover portion to load the syringe is used to activate a pair of main drive springs. In order to fire the loaded and activated auto-injector, the user pushes the shield at the front end of the auto-injector into contact with the injection site (e.g., the user's skin), thereby releasing the drive spring and forcing the drug to pass through the syringe needle and enter the injection site.

[0004] In an effort to improve reliability, manufacturers of autoinjectors seek to identify events that may cause an accidental discharge, for example, or to identify an autoinjector that has been primed and loaded.

[0005] WO2019 / 141985 describes an automatic injector with a removable cap and a locking member for preventing accidental activation. The locking member is movable within the removable cap so that the cap is a two-part component. Summary of the invention

[0006] According to the present invention, there is provided an automatic injector for delivering a dose of a drug from a syringe or cartridge containing the drug having a needle attached thereto to a patient. The automatic injector comprises: a main housing for receiving the syringe or cartridge; a drive mechanism substantially located within the main housing for providing power to deliver the drug from the syringe or cartridge to the patient; and a shield defining an opening therethrough, the shield being coupled to a front end of the main housing and being movable relative to the housing between an extended position and a retracted position, in which the needle tip is substantially shielded, and in which the needle tip can extend through the opening in the shield. The shield is coupled to the drive mechanism so that movement of the shield from the extended position to the retracted position causes or permits release of the drive mechanism to provide the power, and the shield is biased toward the extended position. The cap is configured to be removably attached to the front end of the housing to shield the shield and thereby prevent a user from contacting the shield before removing the cap. In addition, the cap and the shield include corresponding substantially non-flexible structures that can directly mechanically engage each other when the cap is attached to the shell to prevent or limit inward movement of the shield relative to the shell when the cap is attached to the shell.

[0007] The non-flexible formations may depend on the cap and shield and overlap in a direction transverse to an axis of the auto-injector along which the motive force is directed. The non-flexible formations may be integral with the cap and shield from which they depend. Optionally, the non-flexible formations may define respective opposing surfaces having the same or similar non-perpendicular slope relative to the direction.

[0008] The housing may include a first main housing portion and a second main housing portion movable relative to each other between an open position in which the syringe or cartridge can be inserted into a receiving slot defined in the first main housing portion and a closed position in which the inserted syringe or cartridge is securely retained in the receiving slot and in the housing. The shield includes a first shield portion coupled to the first main housing portion and a second shield portion coupled to the second main housing portion, such that when the main housing portions are in the closed position, the shield portions come together to form a substantially unitary shield, and the shield is coupled to the drive mechanism via the first shield portion and the first main housing portion.

[0009] The formations on the shield may be formations on the first shield portion.The cap and first shield portion may each comprise a substantially rigid one-piece or multi-piece moulded plastic part, and the corresponding non-flexible formations may be moulded integrally with one or more of the parts.

[0010] The cap and the main housing may include corresponding cooperating features to facilitate a snap-fit ​​engagement of the cap and the main housing, the non-flexible construction defining relative contact surfaces spaced a distance sufficient to enable a snap-fit ​​engagement and disengagement of the cap and the housing after and before axial alignment of the contact surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A to Figure 1C The autoinjector is shown in (A) a closed state, (B) a partially opened state, and (C) an opened state;

[0012] Figure 2 A safety syringe is shown;

[0013] Figure 3 Shows Figure 1A to Figure 1C a capped end portion of an automatic injector;

[0014] Figure 4A and Figure 4B Shows Figure 1A to Figure 1C A partial cross section of an automatic injector;

[0015] Figure 5A Schematically illustrates the Figure 1A to Figure 1C , Figure 3 as well as Figure 4A and Figure 4B A modification of an auto-injector, wherein the modification provides an anti-activation feature;

[0016] Figure 5B Picture shows Figure 5A Zoomed in details of the modifications;

[0017] Fig. 6A Picture shows Figure 5A the cap of the auto-injector; and

[0018] Figure 6B Picture shows Figure 5A The shield portion of the automatic injector. DETAILED DESCRIPTION

[0019] In seeking to improve the reliability of autoinjectors, and in particular to minimise the risk of accidental firing of a loaded and primed autoinjector, the inventors have recognised that autoinjectors of known type (e.g., those described in WO2022 / 179832 and WO2020 / 064927) can fire accidentally if subjected to a sudden shock. This can occur, for example, when the autoinjector is dropped at its rear end (i.e., the end opposite the injection end) after the device has been loaded and primed, and can occur even when a removable cap shielding the injection end is in place.

[0020] The terms "forward" or "front" are used herein to refer to the needle side or injection site end of the autoinjector, while the term "rear" refers to the end of the autoinjector away from the needle or injection site.

[0021] Figure 1A to Figure 1C An embodiment of a known autoinjector 100 is shown in the following states: A) a closed state; B) a partially open state; and C) a fully open state.

[0022] The autoinjector 100 includes a housing 102 including a body 104 and a cover 106 that are hingedly connected to allow the housing to be opened and closed. The autoinjector further includes a plurality of component parts contained in the housing. For example Figure 2 Syringe 200 ( Figure 1A to Figure 1C The syringe of the automatic injector 100 (not shown) can be received in the housing in the slot 112 defined in the body. The cover 106 of the automatic injector 100 includes a through hole 126, which is positioned so that the surface of the plunger driver 116 is visible after the firing is completed, and the operation of the plunger driver 116 is described below. The surface is brightly colored compared to other parts that are visible through the through hole before and during drug delivery to thereby provide a visual indication to the user that drug delivery is complete.

[0023] like Figure 1A and Figure 1BAs best shown in FIG. 1 , the auto-injector 100 further includes a shield 108 formed by a lower portion 108a and an upper portion 108b. The lower portion and the upper portion are respectively coupled to the body 104 and the cover 106 so that the portions 108a, 108b separate when the housing 102 is open to allow the syringe 200 to be inserted, and come together to form a unitary shield 108 when the housing is closed. The shield 108 defines an aperture through which the needle 210 of the syringe 200 at least partially extends when the syringe is received in the auto-injector 100. The lower portion 108a and the upper portion 108b respectively include a slidable connection with the body 104 and the cover 106 to permit movement between an extended position in which the end of the syringe needle is substantially covered by the shield and a retracted position in which the end of the syringe needle is exposed. The shield portions are individually biased toward the extended position so that the needle of the syringe in the auto-injector remains substantially covered prior to injection.

[0024] The housing portion and the shroud portion may be formed from plastic, for example as moulded plastic parts.

[0025] like Figure 1C As shown in FIG. 1 , the autoinjector 100 includes a removable cap 110 that is typically in place prior to administering an injection. Figure 1A and Figure 1B The cap is omitted. In the illustrated configuration, the cap is slidably mounted on the lower shield portion 108b and further abuts against the front end of the body 104. The cap 110 is intended to prevent a user from accessing the shield and thus prevent accidental firing when the cap is in place. The cap can be formed of a substantially rigid plastic. It can be a single molded piece, or can be formed of two or more plastic parts. The cap can also include metal fingers as described below.

[0026] Figure 2 A safety syringe 200 suitable for use with the described auto-injector 100 is illustrated. Such a syringe 200 is described in detail in WO2019 / 086718. It is sufficient to note here that the syringe includes a syringe body 202 for containing a medicament, a syringe plunger 204 engaged with a stopper 206 in the syringe body, a needle guard 208 coupled to a safety plunger 209, and a needle 210. The coupling between the syringe plunger and the safety plunger / needle guard is such that the needle guard 208 is deployed around the needle of the syringe so as to substantially cover the needle after the medicament is delivered from the syringe body. This coupling is described in detail in WO2019 / 086718.

[0027] Typically, syringes (including safety syringes) are conventionally provided with a protective rigid needle shield (RNS) that needs to be removed before the syringe can be used (the RNS is not Figure 2). For this purpose, the cap 110 also operates as a RNS remover 300 in a known manner. Figure 3 A top plan view of the end of the auto-injector with the cap in place is shown. The auto-injector 100 is in an open state so that the RNS remover and the end of the syringe 200 with the attached RNS 212 are visible. The RNS remover includes a U-shaped wall 302 extending away from the cap, wherein the wall is open at its upper side, and when the cap is assembled to the auto-injector, the U-shaped wall 302 defines a passage 304 for receiving the RNS. The front end of the side wall terminates with a clamping member 306. The clamping member is configured to allow the RNS 212 to be easily inserted into the passage while preventing its subsequent withdrawal. Therefore, when the cap is removed, the RNS can be removed from the syringe. It will be appreciated that the RNS remover 300 (as part of the cap 110) is configured to fit within the shield 108 and slide within the shield 108.

[0028] exist Figure 3 In the configuration shown in FIG. 1 , the gripping member 306 includes a protrusion 308 extending inwardly into the passage 304, the protrusion 308 being angled away from the front end of the side wall 302. The gripping member 306 may be provided by a flexible metal leg secured within the cap 110. When the syringe 200 with the RNS is inserted into the slot 112 of the body 104, the protrusion 308 is able to flex outwardly, and when the protrusion 308 is brought into engagement with the RNS 212, any return movement is prevented by the protrusion 308.

[0029] Figure 4A and Figure 4B A partial cross-sectional view of the auto-injector 100 during various stages of activation is shown to illustrate the presence and operation of other internal components during the opening and closing strokes of the cap 106. In particular, it can be seen that the auto-injector 100 includes: a shuttle 114, which is operable to move between a first forward position and a second rearward position along a shuttle guide 120 on the body 104 of the housing 102; a plunger driver 116, which is used to drive the syringe plunger 204; and a biasing element 118, which couples the shuttle and the plunger driver 116. The shuttle and the plunger driver are slidably connected to the shuttle guide 120 to permit rearward and forward movement within the housing 102. Unlike the plunger driver, the shuttle is also fixedly connected to the cap 106 via two arm members 122. The plunger driver includes a rearmost member 117, referred to herein as a "pushing member", which is located behind the rear end of the plunger of the inserted syringe in use.

[0030] The biasing element 118 includes two extension springs on either side of the device, although only one is visible in the drawings. Prior to any activation, these springs are under slight tension in order to hold the plunger driver 116 and the shuttle 114 together. Therefore, it should be noted that in the context of the extension spring, activation refers to the process of further tensioning the extension spring into a state in which firing can be initiated.

[0031] Each of the shuttle guide 120 and the plunger driver 116 comprises a portion of a latch arrangement configured to cooperate to secure the plunger driver at the rear end of the autoinjector 100. Suitable latch arrangements are described in WO2022 / 179832.

[0032] The autoinjector 100 further includes a torsion spring 124 disposed at the hinged connection between the cover 106 and the body 104 of the autoinjector 100. The torsion spring is coupled to both the cover and the body. In the illustrated embodiment, one end of the torsion spring is attached to the cover and the opposite end is attached to the body of the autoinjector.

[0033] The automatic injector is now described in the cap opening stroke ( Figure 4A ) and cover closing stroke ( Figure 4B ) is activated. WO2021058474 describes the operation of a similar automatic injector, except that the biasing element described therein further includes a compression spring.

[0034] When the cover 106 is opened, the arm member 122 that couples the cover and the shuttle 114 together causes the shuttle to move backward from the first position to the second position. The shuttle is constantly engaged with the plunger driver 116 so that its backward travel causes the same backward travel for the plunger driver. Therefore, the extension spring connected between them remains unactivated (i.e., further extended) during the cover opening. Near the end of the cover opening stroke, the latch arrangement portion on the shuttle guide 120 and the plunger driver are brought together so that they can cooperate to fix the plunger driver at the rear end of the automatic injector 100.

[0035] The opening of the lid 106 also causes the end of the torsion spring 124 attached to the lid to rotate about its spring axis relative to the opposite end of the torsion spring. This activates the torsion spring when the lid is opened. When activated, the torsion spring generates a restoring force tending to push the lid closed.

[0036] When the lid 106 is closed, the plunger driver 116 is retained at the rear of the autoinjector by the latch arrangement while the shuttle 114 is free to move forward to the first position along the shuttle guide 120. Thus, during the lid closing stroke, the shuttle and plunger driver are separated and the extension spring coupled therebetween is activated (i.e., further tensioned).

[0037] As already noted above, the activated torsion spring 124 pushes the cap 106 closed. This helps to activate the tension spring 118 during closing, while requiring minimal force to activate the torsion spring during opening. This is important for users of the autoinjector, who would otherwise find it difficult to apply the necessary force to close the cap.

[0038] The firing of the automatic injector is now described. The firing mechanism is described in more detail in WO2022179832.

[0039] To fire the loaded and activated auto-injector, the user advances the front end of the auto-injector 100 into contact with the injection site (e.g., the user's skin). This causes the shield portions 108a, 108b to move into the retracted position against their bias (e.g., corresponding springs). When the shield is retracted into the housing 102, the lower shield 108b permits or causes the release of the latch arrangement and the activated tension springs 118a, 118b. The restoring force of the tension spring acting on the plunger driver 116 drives the plunger driver forward, and specifically the push member 117, to depress the syringe plunger and force the drug out of the syringe needle into the injection site.

[0040] It has been found that in some instances, even when the removable cap 110 is in place, a loaded and activated auto-injector of the general structure described may be accidentally fired. This may occur when the auto-injector falls on its rear end. It should be noted that auto-injectors are typically used by people with limited mobility, and as such, accidental drops of the auto-injector can be expected. The cause of such accidental firing is suspected to be due to the reaction force of the shield (specifically, the lower shield portion 108b) driven inwardly relative to the housing 102. According to the current design, the cap 110 does not provide a dedicated mechanism to prevent the risk of such inward movement of the shield 108. Although WO2019 / 141985 may point to a solution, this is disadvantageous because it requires manufacturing and inserting another component in the cap.

[0041] exist Figure 5A and Figure 5B The simple and elegant solution is shown in the figure. Figure 5B yes Figure 5ADetail B of the embodiment of the present invention is an enlarged view of the embodiment of the present invention. This is a specific example of a device for latching the removable cap 110 and the shield 108 together to effectively prevent accidental rearward movement of the shield when the cap is in place. The cap 110 defines a slot 400 on the inner surface extending laterally across the area of ​​the cap. The slot is configured to cooperate with a lip 401 formed at the front edge of the body 104 of the housing 102 so that when the cap is pushed onto the front of the housing, the lip 401 snaps into the gap behind the slot 400, thereby firmly but releasably holding the cap in place. Additional slots and lips may be provided on the sides of the cap and the main housing (front) to help secure the cap in place, although these are not shown in the drawings.

[0042] A catch 402 projects downwardly from a base 403 of the RNS remover (U-shaped wall 302) portion of the cap. The catch is supported by a pair of legs 404, such as Fig. 6A As best shown in Figure 5A , Figure 5B and Figure 6B As will be apparent, the lower shield portion 108b is provided with a shoulder 405 proximate its front end. Both the latch 402 and the shoulder 405 are integrally molded with the cap and shield portions from which they depend, and are substantially inflexible relative to those portions. Specifically, the latch and shoulder provide no axial movement, and preferably no lateral movement, relative to the portions to which they are attached.

[0043] When the cap 110 is initially assembled onto the housing 102 and over the shield 108, and before the snap-fit ​​engagement of the slot(s) 400 and the cooperating lip(s) 401, the cap and lower shield 108b can move relative to each other enough to allow the latch 402 and the end of the shoulder 405 to pass over each other. Once this has occurred, further movement of the cap 110 toward the housing 102 causes the snap-fit ​​engagement of the slot(s) 400 and the cooperating lip(s) 401. Once the cap 110 is snapped onto the housing 102 in place, the two parts are substantially rigidly connected.

[0044] Consider now the event that the shield 108, and in particular the lower shield portion 108b, is driven rearwardly into the main housing, for example, the device is accidentally dropped onto its rear end. After only very small movement of the lower shield portion, the shoulder 405 will strike the catch 402. Since both features are non-flexible, any further rearward movement of the lower shield portion 108b into the housing will be blocked. Thus, this direct mechanical contact between the shoulder and the opposing face of the catch will prevent accidental firing of the device while the cap is in place.

[0045] When a user chooses to remove the cap 110 from the housing 102 to expose the shield 108 prior to use, pulling on the cap initially disengages the cap from the housing. Figure 5B The relative movement of the cap and shield permitted before the catch 402 and the shoulder 405 come into contact is illustrated with the legend "x". This distance is sufficient to allow disengagement of the snap-fit ​​connection between the cap and the housing. After such disengagement, the cap can be tilted relative to the housing by the user to allow the ends of the catch and the shoulder to pass over each other. The cap 110 can then be completely removed.

[0046] To better facilitate complete disengagement of the cap and housing, the opposing surfaces 406, 407 of the latch 402 and shoulder 405 may be arranged at an angle offset from a direction transverse to the axis of the device, i.e., the surfaces may be inclined. The angled surfaces facilitate tilting of the cap relative to the shield to facilitate disengagement. The angle relative to the transverse direction may be between 5 and 45 degrees.

[0047] Those skilled in the art will be able to envision other embodiments of the invention without departing from the scope of the appended claims. For example, rather than providing the mating formations as a first lip extending upwardly from the lower shield portion and a second lip extending downwardly from the base of the RNS remover, features may be provided on the lower surface of the lower shield portion and on a portion of the cap below the lower shield portion. Other configurations will be apparent.

Claims

1. An automatic injector for delivering a dose of a drug to a patient from a syringe or cartridge containing the drug, the syringe or cartridge having a needle attached to the syringe or cartridge, the automatic injector comprising: a main housing for receiving the syringe or cartridge; a drive mechanism, the drive mechanism being substantially located within the main housing and configured to provide motive force to deliver drug from the syringe or cartridge to the patient; a shield defining an opening therethrough, the shield coupled to the front end of the main housing and movable relative to the housing between an extended position in which the needle tip is substantially shielded and a retracted position in which the needle tip is extendable through the opening in the shield, the shield coupled to the drive mechanism such that movement of the shield from the extended position to the retracted position causes or permits release of the drive mechanism to provide the motive force, and the shield is biased toward the extended position; as well as a cap configured to be removably attached to the front end of the housing to shield the shield and thereby prevent a user from contacting the shield before removing the cap, wherein the cap and the shield include corresponding substantially inflexible structures that are capable of directly mechanically engaging with each other when the cap is attached to the shell to prevent or limit inward movement of the shield relative to the shell when the cap is attached to the shell.

2. The automatic injector according to claim 1, wherein: The inflexible formation is suspended from the cap and shield and overlaps in a direction transverse to an axis of the autoinjector along which the motive force is directed.

3. The automatic injector according to claim 2, wherein: The non-flexible configurations define respective opposing surfaces having the same or similar non-perpendicular slopes relative to the direction.

4. An autoinjector according to any preceding claim, wherein The non-flexible constructions are integral with their respective caps and shields.

5. An automatic injector according to any one of the preceding claims, the housing comprising a first main housing part and a second main housing part which are movable relative to each other between an open position in which the syringe or cartridge can be inserted into a receiving slot defined in the first main housing part, and a closed position in which the inserted syringe or cartridge is securely retained in the receiving slot and in the housing, in, The shroud includes a first shroud portion coupled to the first main housing portion and a second shroud portion coupled to the second main housing portion such that when the main housing portions are in the closed position, the shroud portions come together to form a substantially unitary shroud, and The shield is coupled to the drive mechanism through the first shield portion and the first main housing portion.

6. The automatic injector according to claim 5, wherein: The formation on the shield is a formation on the first shield portion.

7. The automatic injector according to claim 5 or 6, wherein: The cap and first shield portion each comprise a substantially rigid one- or multi-part molded plastic part, and the respective non-flexible formations are integrally molded with one or more of the parts.

8. An automatic injector according to any one of the preceding claims, wherein the cap and the main housing include corresponding cooperating features to facilitate snap-fit ​​engagement of the cap and the main housing, the non-flexible construction defining opposing contact surfaces spaced apart a distance sufficient to enable snap-fit ​​engagement and disengagement of the cap and the housing after and before axial alignment of the contact surfaces.

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