Injection device

Abstract

An autoinjector, comprising: a body for receiving a syringe containing a medicament; and a drive mechanism located within the body and having a plunger drive movable through the body, the drive mechanism including one or more drive springs that can be pre-tightened and released to move the plunger drive, the drive mechanism further includes one or more damping elements of elastomeric material for contacting the or each drive spring to damp vibrations of the spring or springs upon release.

Description

Technical Field

[0001] The present invention relates to an auto - injector for drug delivery, the auto - injector being provided with a noise damper of elastic or viscous material. Background Art

[0002] An injection device is a device for delivering a dose of a drug from a syringe or cartridge containing the medicament without the user having to manually apply power to drive a syringe plunger or cartridge stopper. The injection device may include an injection device designed to provide a single dose, or alternatively, a pen device in which the user can set the dose of the drug to be provided. Typical injection devices such as auto - injectors and pen devices use a strong helical spring that is pre - tensioned and fired to provide this power. Summary of the Invention

[0003] According to a first aspect of the present invention, there is provided an injection device comprising: a body for receiving a syringe containing a medicament; and a drive mechanism located within the body and having a plunger driver capable of moving through the body, the drive mechanism including one or more drive springs and one or more damping elements of elastic material, the drive springs being capable of being pre - tensioned and released to move the plunger driver, the damping elements being for contacting the or each drive spring to damp the vibration of the spring or springs after release. Advantageously, the noise damping elements are independent of any structure within the injection device other than the drive springs. This means that any vibration generated by the springs is not transmitted to another structure.

[0004] The one or more damping elements may be elongate members disposed within the or each drive spring. The lateral outer dimension of the or each damping element may be less than the lateral inner diameter of the drive spring in which the damping element is disposed to allow relative movement. The length of the or each damping element may be greater than the relaxed length of the drive spring in which the damping element is disposed.

[0005] One or more damping elements may be cylinders, such as cylindrical rods or cylindrical tubes.

[0006] The injection device may further include a shuttle configured to travel along a shuttle guide within the body of the injection device during pre - tensioning. The shuttle guide is coupled to the plunger driver by the one or more drive springs. Before pre - tensioning, the one or more drive springs are slightly tensioned such that adjacent turns of the spring are spaced apart. This can be achieved, for example, if before pre - tensioning, the shuttle and the plunger driver are engaged and their combined length is configured to impart a slight tension to the one or more drive springs.

[0007] The elastic material of the one or more damping elements may be an elastomeric polymer such as natural rubber, synthetic rubber or a mixture thereof.

[0008] The one or more damping elements may alternatively be provided as a sleeve through which the or each drive spring extends, or as a coating on the or each drive spring.

[0009] The one or more drive springs may be pre-tensioned by a user action.

[0010] According to a second aspect of the present invention, there is provided an injection device comprising: a body for receiving a syringe containing a medicament; and a drive mechanism located within the body and having a plunger driver movable through the body. The drive mechanism includes one or more drive springs that can be pre-tensioned and released to move the plunger driver. One or more of the drive springs are at least partially coated with a viscous material that inhibits vibration of the spring after spring release. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figures 1A to 1C An auto-injector is shown in (A) the closed, (B) the partially open and (C) the open states;

[0012] Figure 2 A safety syringe is shown;

[0013] Figure 3 is shown Figures 1A to 1C the capped end of the auto-injector;

[0014] Figure 4A and Figure 4B is shown Figures 1A to 1C a partial cross-sectional view of the auto-injector;

[0015] Figure 5 is shown Figures 1A to 1C the shuttle, plunger driver and biasing element of the auto-injector; and

[0016] Figure 6A and Figure 6B is shown Figures 1A to 1C the biasing element and noise damping element of the auto-injector. DETAILED DESCRIPTION

[0017] An auto-injector is proposed having a noise damping element coupled to a biasing element such that after pre-tensioning and firing of the biasing element, any possible lateral and / or longitudinal vibrations are suppressed.

[0018] The terms "forward" or "front" are used herein to refer to the needle side or the injection site end of the auto-injector, while the term "rear" refers to the end of the auto-injector that is remote from the needle or the injection site.

[0019] Figures 1A to 1C An embodiment of an auto-injector 100 is shown in: A) a closed state; B) a partially open state; and C) a fully open state.

[0020] The auto-injector 100 includes a housing 102, which includes a body 104 and a cap 106, and the body 104 and the cap 106 are hingedly connected to allow the housing to be opened and closed. The auto-injector also includes a plurality of component parts housed within the housing. A syringe such as Figure 2 syringe 200 (not shown in Figures 1A to 1C ) can be received within the housing in a slot 112 defined in the body. The cap 106 of the auto-injector 100 includes a through-hole 126, and the through-hole 126 is positioned such that once firing is complete, the surface of the plunger driver 116 (its operation is described below) is visible. This surface is distinctly colored compared to other parts visible through the through-hole before and during drug delivery, thus providing a visual indication to the user of the completion of drug delivery.

[0021] As Figure 1A and 1B most clearly shown, the auto-injector 100 also includes a protective cover 108 formed by a lower portion 108a and an upper portion 108b. The lower and upper portions are respectively coupled to the body 104 and the cap 106 such that when the housing 102 is opened, the portions 108a, 108b separate to allow insertion of the syringe 200, and when the housing is closed, the portions 108a, 108b are joined together to form an integral protective cover 108. The protective cover 108 defines an aperture through which at least a portion of the needle 210 of the syringe 200 extends when the syringe is received within the auto-injector 100. The lower portion 108a and the upper portion 108b respectively include slidable connections to the body 104 and the cap 106 to allow movement between a retracted position and an extended position, in which the end of the syringe needle is substantially covered by the protective cover and in which the end of the syringe needle is exposed. The protective cover portions are individually biased towards the extended position such that the needle of the syringe within the auto-injector remains substantially covered prior to injection.

[0022] As Figure 1C shown, the auto-injector 100 includes a removable cap 110, which is typically in place prior to performing an injection. For ease of understanding, from Figure 1A and 1BThe cap is omitted. In the configuration shown, the cap is slidably fitted over the lower shroud portion 108b and further abuts against the front end of the body 104. The cap 110 prevents the user from accessing the shroud and thus prevents accidental firing when the cap is in place.

[0023] Figure 2 A safety syringe 200 adapted to be used with the auto-injector 100 is shown. Such a syringe 200 is described in detail in WO2019086718. It suffices here to note that the syringe includes a syringe body 202 for containing a medicament, a syringe plunger 204 engaged with a stopper 206 within the syringe body, a needle shield 208 coupled to the syringe plunger, and a needle 210. The coupling between the syringe plunger and the needle shield causes the needle shield 208 to deploy around the needle of the syringe so as to substantially cover the needle after delivery of the medicament from the syringe body. This coupling is described in detail in WO2019 / 086718.

[0024] Generally, syringes (including safety syringes) are typically provided with a protective rigid needle shield (RNS) which needs to be removed before the syringe can be used (the RNS is not shown in Figure 2 ). For this purpose, the cap 110 also operates as an RNS remover 300 in a known manner. Figure 3 A top view of the end of the auto-injector with the cap in place is shown. The auto-injector 100 is in an open state such that the end of the RNS remover and the syringe 200 with the attached RNS 212 are visible. The RNS remover includes side walls 302 extending away from the cap, and the side walls 302 define a channel 304 for receiving the RNS when the cap is assembled to the auto-injector. The front end of the side walls terminates in a gripping member 306. The gripping member is configured to allow the RNS 212 to be easily inserted into the channel while preventing its subsequent withdrawal. Thus, when the cap is removed, the RNS can be removed from the syringe.

[0025] In Figure 3 the configuration shown, the gripping member 306 includes a protrusion 308 extending inwardly into the channel 304, the protrusion being angled away from the front end of the side wall 302. When the syringe 200 with the RNS is inserted into the slot 112 of the body 104, the protrusion 308 is capable of bending outwardly, and when the protrusion 308 engages the RNS 212, the protrusion 308 prevents any return movement.

[0026] Figure 4A and Figure 4BA partial cross-sectional view of the auto-injector 100 during various stages of being pre-tensioned is shown to illustrate the presence and operation of additional 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 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 for driving a syringe plunger 204; and a biasing element 118 coupling the shuttle and the plunger driver 116. The shuttle and the plunger driver are slidably connected to the shuttle guide 120 to allow backward and forward movement within the housing 102. Different from the plunger driver, the shuttle is also fixedly connected to the cap 106 via two arm members 122.

[0027] Figure 5 An assembled arrangement of the shuttle, the plunger driver, and the biasing element before being pre-tensioned is shown, i.e., this is the configuration of the arrangement in situ within the device and before being pre-tensioned. As shown, the biasing element 118 includes two tension springs 118a, 118b that are slightly tensioned before any pre-tensioning to hold the plunger driver 116 and the shuttle 114 together. Therefore, it should be noted that in the context of the tension springs, being pre-tensioned refers to the process of further tensioning the tension springs to a state where firing can be prepared to be initiated.

[0028] Each of the shuttle guide 120 and the plunger driver 116 includes a part of a latching arrangement configured to cooperate to fix the plunger driver at the rear end of the auto-injector 100. A suitable latching arrangement is described in WO2022179832.

[0029] The auto-injector 100 further includes a torsion spring 124 disposed at a hinge connection between the cap 106 and the body 104 of the auto-injector 100. The torsion spring is coupled to both the cap and the body. In the illustrated embodiment, one end of the torsion spring is attached to the cap, and the opposite end is attached to the body of the auto-injector.

[0030] Now, the pre-tensioning of the auto-injector during the cap opening stroke ( Figure 4A ) and the cap closing stroke ( Figure 4B ) is described. WO2021058474 describes the operation of a similar auto-injector, except that the biasing element described therein further includes a compression spring.

[0031] When the cap 106 is opened, the arm member 122 that couples the cap and the shuttle 114 causes the shuttle to move backward from the first position to the second position. As Figure 5As most clearly shown, the shuttle remains continuously engaged with the plunger driver 116 such that its backward stroke causes the same backward stroke of the plunger driver. Accordingly, the tension springs 118a, 118b coupled therebetween remain un-preloaded (i.e., further extended) during lid opening. Near the end of the lid opening stroke, the latch arrangement portion on the shuttle guide 120 and the plunger driver engage together such that they can cooperate to fix the plunger driver at the rear end of the autoinjector 100.

[0032] 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 induces the torsion spring on the lid opening. When ready, the torsion spring generates a restoring force that tends to urge the lid to close.

[0033] When closing the lid 106, the plunger driver 116 is held at the rear of the autoinjector by the latch arrangement while the shuttle 114 freely moves forward along the shuttle guide 120 to the first position. Accordingly, during the lid closing stroke, the shuttle and the plunger driver separate and the tension springs 118a, 118b coupled therebetween are preloaded (i.e., further tensioned).

[0034] As already noted above, the preloaded torsion spring 124 urges the lid 106 to close. This helps to preload the tension spring 118 during closing while requiring minimal force to preload the torsion spring during opening. This is important for the user of the autoinjector, who would otherwise find it difficult to apply the necessary force to close the lid.

[0035] Now the firing of the autoinjector is described. The firing mechanism is described in more detail in WO2022179832.

[0036] To fire the loaded and pre-activated autoinjector, the user pushes the front end of the autoinjector 100 into contact with the injection site (e.g., the user's skin). This causes the shield portions 108a, 108b to move to the retracted position against their biasing (e.g., respective springs). When the shield retracts into the housing 102, the lower shield 108b allows or causes the release of the latch arrangement and the preloaded tension springs 118a, 118b. The restoring force of the tension spring acting on the plunger driver 116 drives the plunger driver forward to press the syringe plunger and force the drug out of the syringe needle into the injection site.

[0037] Figure 6AA schematic view showing one end of tension springs 118a, 118b coupled to a plunger driver 116 is shown. The tension springs have annular ends 128 that can be fitted around an attachment point 130 on the plunger driver. The annular ends are fixed in place around the attachment point 130 by tabs 132. An equivalent coupler is provided at the shuttle 114. As already mentioned, the release of the tension springs releases a large amount of energy, which, without mitigation, can lead to excessive noise, disturbing the user. For this reason, it is proposed that a noise damping element 134 be coupled to the biasing element 118 such that any lateral and / or longitudinal vibrations that may occur during or immediately after firing are suppressed.

[0038] Figure 6B A view showing the noise damping element 134 and the tension springs 118 before being assembled within the device when the springs are in a relaxed state is shown. As shown, the noise damping element 134 can take the form of rubber (or other elastic material) cylinders 134a, 134b, where the two cylinders are inserted into the corresponding tension springs 118a, 118b. The diameter of the cylinders 134a, 134b is slightly smaller than the inner diameter of the tension springs 118a, 118b to allow movement within the springs. This prevents the cylinders from getting stuck on the tension springs during firing. The cylinders are held within the tension springs at either end by the shuttle 114 and the plunger driver 116. When in the relaxed state, the length of the cylinders is slightly greater than the length of the coiled region 118c between the two annular ends 128 of the tension springs. In some examples, when each cylinder is assembled in the device and the spring is in an unpreloaded state, the length of each cylinder is also greater than the coiled region of the tension spring. Cylinders of these dimensions are particularly suitable for suppressing longitudinal and lateral vibrations.

[0039] Any lateral vibrations generated during firing (or otherwise) will cause the inner surfaces of the tension springs 118a, 118b to move into contact with the cylinders 134a, 134b. The cylinders limit this lateral displacement, thereby reducing the amplitude and duration of any lateral vibrations. The cylinders formed of rubber, synthetic rubber or a similar elastic material effectively convert the kinetic energy of the tension springs into heat (which does not generate noise itself). Advantageously, the noise damping element is independent, i.e., independent of any structure within the injection device other than the spring. This means that any vibrations generated by the spring are not transmitted to another structure.

[0040] During firing, longitudinal vibrations mainly develop and propagate as adjacent turns in the central coiled region 118c bounce off each other. However, in the case where the cylinders 134a, 134b are inserted into the tension springs, the cylinders must be compressed before the adjacent turns can come into contact with each other. The compression of the cylinders dissipates energy, which means that the longitudinal vibrations formed due to the contact between adjacent turns are suppressed. In this way, the cylinders are able to suppress longitudinal vibrations during firing.

[0041] Returning to Figure 5 it can be seen that the combined length of the shuttle 114 and the plunger driver 116 is greater than the length of the central coiled region 118c of the tension springs 118a, 118b, such that the tension springs are in tension even before they are pre-tensioned. This advantageously spaces the adjacent turns in the tension springs to reduce the spring-back of the coils upon firing. Additionally, since the tension springs cannot physically enter a compressed state, resonance modes caused by spring oscillations between the compressed and tensioned states can be suppressed.

[0042] Although the noise damping element 134 has been described as a hollow cylinder, other cross-sections and forms are possible. For example, it could be a rubber sleeve through which the tension spring extends or a rubber coating disposed on the tension spring. To avoid adjacent turns in the spring sticking together, the rubber coating can be applied to the spring while the spring is in a stretched state.

[0043] In some alternative embodiments, the tension springs 118a, 118b are at least partially coated with a viscous material (e.g., a known smart grease). The coating can be applied manually or by dipping the spring into a bucket containing the viscous material. The viscous material adheres to the spring with only very limited flow while exhibiting a tendency to absorb mechanical energy during spring vibration, which is dissipated as heat.

[0044] It is also conceivable that multiple noise damping elements can be inserted within each tension spring. Then, the length of the above-described damping elements should be interpreted as the total length of those damping elements. Other noise damping materials are also possible and would be envisioned by those skilled in the art. Examples include synthetic rubbers such as neoprene, polymers such as silicone, and foams.

[0045] Any of the other biasing elements described above (e.g., a torsion spring, a spring that biases the shield 108 to the extended position) can also be fitted with a noise damping element.

[0046] Although the above invention has been described with respect to an auto-injector, those skilled in the art will understand that it can also be applied to other injection devices, such as pen devices where the user manually selects the size of the dose of medicament to be administered.

[0047] Without departing from the scope of the appended claims, those skilled in the art will be able to envision other embodiments of the present invention.

Claims

1. An injection device, comprising: a body for receiving a syringe containing a medicament; and a drive mechanism located within the body and having a plunger driver that is movable through the body, the drive mechanism including one or more drive springs that can be pre - tightened and released to move the plunger driver, the drive mechanism further including one or more damping elements of an elastic material that are independent of the body and contact the drive spring or each drive spring to suppress vibration of the spring or springs after release.

2. The injection device according to claim 1, wherein the one or more damping elements are elongate members disposed within the drive spring or each drive spring.

3. The injection device according to claim 2, wherein the lateral outer dimension of the damping element or each damping element is less than the lateral inner diameter of the drive spring in which the damping element is disposed to allow relative movement.

4. The injection device according to any one of claims 2 to 3, wherein the length of the damping element or each damping element is greater than the relaxed length of the drive spring in which the damping element is disposed.

5. The injection device according to any one of the preceding claims, wherein each of the one or more damping elements is a cylinder.

6. The injection device according to any one of the preceding claims, further comprising: a shuttle configured to travel along a shuttle guide within the body of the injection device during pre - tightening, and the shuttle is coupled to the plunger driver by the one or more drive springs, wherein, before pre - tightening, the one or more drive springs are slightly tensioned such that adjacent turns of the spring are spaced apart.

7. The injection device according to claim 6, wherein before pre - tightening, the shuttle and the plunger driver are engaged, and the combined length of the shuttle and the plunger driver is configured to impart the slight tension to the one or more drive springs.

8. The injection device according to any one of the preceding claims, wherein the elastic material of the one or more damping elements is an elastomeric polymer.

9. The injection device according to claim 8, wherein the elastomeric polymer is natural rubber, synthetic rubber, or a mixture thereof.

10. The injection device according to claim 1, wherein the one or more damping elements are provided as sleeves through which the drive spring or each drive spring extends.

11. The injection device according to claim 1, wherein the one or more damping elements are provided as a coating on the drive spring or each drive spring.

12. The injection device according to any one of the preceding claims, wherein the one or more drive springs can be pre - tightened by a user action.

13. An injection device, comprising: a body for receiving a syringe containing a medicament; and a drive mechanism located within the body and having a plunger driver movable through the body, the drive mechanism including one or more drive springs that can be pre-tensioned and released to move the plunger driver, wherein the one or more drive springs are at least partially coated with a viscous material that inhibits vibration of the spring or springs after release.

14. The injection device according to claim 13, further comprising: a shuttle configured to travel along a shuttle guide in the body of the injection device during pre-tensioning, and the shuttle being coupled to the plunger driver by the one or more drive springs, wherein, before pre-tensioning, the one or more drive springs are slightly tensioned such that adjacent turns of the spring are spaced apart.

15. The injection device according to claim 14, wherein, before pre-tensioning, the shuttle and the plunger driver are engaged and the combined length of the shuttle and the plunger driver is configured to impart the slight tensioning of the one or more drive springs.

16. The injection device according to any one of claims 13 to 15, wherein, the one or more drive springs can be pre-tensioned by a user action.

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