Injectors and drive systems for auto-injectors

Abstract

Injectors and drive modules for injectors are provided, for delivering an agent from a syringe within a housing. The injector includes an activation cap covering a needle of the syringe that moves proximally when pressed against a subject's skin to insert the needle. A spacer is operatively coupled to the activation cap such that, proximal movement of activation cap causes the spacer to compress a spring until a spring force exceeds a threshold, thereby causing a release cap to move and release an opener pin to open a canister and release pressurized, gas to advance a plunger to deliver an agent from the syringe through the needle into the subject's body.

Description

INJECTORS AND DRIVE SYSTEMS FOR AUTO-INJECTORS RELATED APPLICATION DATA

[0001] The present application claims benefit of co-pending U.S. provisional application Serial No. 63 / 569,556, filed March 25, 2024, the entire disclosure of which is expressly incorporated by reference herein. The present application is related to U.S. Patent Nos. 10,716,892, 10,912,883, and 11,071,824, and U.S. Publication No. 2024 / 0033434, the entire disclosures of which are expressly incorporated by reference herein. TECHNICAL FIELD

[0002] The present application relates generally to devices and methods for delivering agents into a subject’s body and, more particularly, to injectors and / or gas- powered drive systems for injection devices, and to methods for making and using such devices. BACKGROUND

[0003] There are many applications involving delivery of a medicament or other agent subcutaneously, intramuscularly, or otherwise into a patient’s body. For example, auto-injectors are available that include a predetermined dose of the agent that may be delivered automatically into the patient’s body, e.g., after placement against the patient’s skin and activation. Generally, such auto-injectors are spring-loaded syringes that are activated to release the spring, which generates sufficient force to penetrate the skin with a needle and deliver the dose within the syringe. For viscous fluids, the forces required to develop fluid flow can be higher than those that spring-powered systems can provide. When springs can be used, they must generate a relatively high force that requires springs of high mass. Consequently, such auto-injectors may make substantial noise, create pressure spikes in the syringe leading to glass breakage, vibrate, and / or may drive the needle forcefully into the patient’s skin, which may cause pain and / or may startle the user, particularly when the patient is administering the injection themselves.

[0004] Therefore, improved devices and methods for delivering agents into a patient’s body would be useful.SUMMARY

[0005] The present application relates generally to devices and methods for delivering agents into a subject’s body and, more particularly, to injectors and / or gas- powered drive systems for injection devices, e.g., to actuators that may be included in such devices, and to methods for making and using such devices.

[0006] In accordance with one example, a device is provided for delivering one or more agents into a subject’s body that includes an outer housing comprising a proximal portion terminating in a proximal end and a distal portion terminating in a distal end; a syringe comprising a barrel within the distal portion containing one or more agents, a needle extending distally from the barrel such that a tip of the needle extends from the distal end, and a piston within a proximal end of the barrel; an activation cap on the distal end of the housing initially positioned such that a contact surface thereof is disposed distal to the distal end and the activation cap covers the needle, the activation cap movable proximally relative to the outer housing to expose the needle when the contact surface is pressed against the subject’s skin to insert the needle; an inner housing within the outer housing proximal portion comprising a first chamber adjacent the outer housing proximal end and a second chamber; a canister containing of pressurized gas within the first chamber; a release cap within the proximal portion adjacent the proximal end and coupled to a carriage carrying an opener pin positioned adjacent an outlet of the canister; a spacer within the outer housing comprising a first end operatively coupled to the activation cap such that the spacer moves proximally when the activation cap moves proximally; a return spring operatively coupled between the spacer and the release cap such that, when the activation cap and spacer move proximally, the return spring is compressed by the spacer to apply a proximal spring force on the release cap and, when the spring force is greater than a trigger force preventing movement of the release cap, the release cap moves proximally to release the carriage, whereupon the carriage causes the opener pin to open the outlet and release the pressurized gas; and a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe, wherein, when the pressurized gas is released from the canister, the pressurized gas passes from the first chamber into the second chamber to apply a distal force to advance the plunger to direct the piston distally to deliver the one or more agents through the needle.

[0007] In accordance with another example, a device is provided for delivering one or more agents into a subject’s body that includes an outer housing comprising a proximalportion terminating in a proximal end and a distal portion terminating in an open distal end; a syringe comprising a barrel containing one or more agents, a needle extending distally from the barrel such that a tip of the needle is disposed within the distal portion adjacent the distal end, and a piston within a proximal end of the barrel; an inner housing within the outer housing comprising a first chamber adjacent the outer housing proximal end and a second chamber between the first chamber and the barrel proximal end; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the outer housing distal end and an activation cap extension extends proximally around the barrel; a source of pressurized gas within the first chamber; a release cap within the outer housing adjacent the outer housing proximal end carrying an opener pin located adjacent the source of pressurized gas; a spacer adjacent the inner housing within the outer housing comprising a distal end adjacent a proximal end of the activation cap extension and a proximal end adjacent the release cap; a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe; the activation cap movable axially relative to the outer housing such that, when the contact surface of the activation cap is pressed against a subject’s skin, the activation cap is configured to move proximally to direct the spacer proximally, the spacer consequently directing the release cap proximally to release the opener pin, thereby causing the opener pin to open the source of pressurized gas to release the pressurized gas into the first chamber and into the second chamber such that the pressurized gas advances the plunger to direct the piston distally to deliver the one or more agents through the needle; and a biasing mechanism configured to bias the spacer to advance distally such that, when the activation cap is released when the contact surface is directed away from the subject’s skin after delivering the one or more agents, the spacer directs the activation cap distally to cover the needle, wherein the force generated by the biasing mechanism when the activation cap and spacer are directed proximally is greater than a trigger force required to direct the release cap proximally.

[0008] For example, the biasing mechanism may include a spring disposed around the inner housing between the spacer and an extension of the release cap such that the force generated by the spring when the activation cap and spacer are directed proximally acts on the release cap to direct the release cap proximally when the spring force is greater than the trigger force.

[0009] In accordance with still another example, a device is provided for delivering one or more agents into a subject’s body that includes an outer housing comprising aproximal portion terminating in a proximal end and a distal portion terminating in an open distal end; a syringe comprising a barrel containing one or more agents, a needle extending distally from the barrel such that a tip of the needle is disposed within the distal portion adjacent the distal end, and a piston within a proximal end of the barrel; an inner housing within the outer housing comprising a first chamber adjacent the outer housing proximal end and a second chamber between the first chamber and the barrel proximal end; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the outer housing distal end and an activation cap extension extends proximally around the barrel; a source of energy within the first chamber; a release cap within the outer housing operatively coupled to the source of energy; a spacer adjacent the inner housing within the outer housing comprising a distal end adjacent a proximal end of the activation cap extension and a proximal end adjacent the release cap; a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe; the activation cap movable axially relative to the outer housing such that, when the contact surface of the activation cap is pressed against a subject’s skin, the activation cap is configured to move proximally to direct the spacer proximally, the spacer consequently directing the release cap proximally to release energy from the source of energy, thereby advancing the plunger to direct the piston distally to deliver the one or more agents through the needle; and a biasing mechanism configured to bias the spacer to advance distally such that, when the activation cap is released when the contact surface is directed away from the subject’s skin after delivering the one or more agents, the spacer directs the activation cap distally to cover the needle, wherein, when the force generated by the biasing mechanism when the activation cap and spacer are directed proximally is greater than a trigger force required to direct the release cap proximally, the release cap moves to release the energy from the energy source.

[0010] Other aspects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] It is believed the present invention will be better understood from the following description of certain examples taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which:

[0012] FIG. 1 is a perspective view of an exemplary auto-injector device including a front and rear housing, and a safety cap.

[0013] FIGS. 2A and 2B are longitudinal cross-sections of an exemplary auto- injector device showing internal components of the device including a syringe carrying one or more agents.

[0014] FIGS. 3A and 3B are details of the distal end of the device of FIGS. 2A and 2B before use, showing a safety cap covering an activation cap and needle of the device.

[0015] FIGS. 4A-4C are cross-sections of the device of FIGS. 2A and 2B, showing activation of the device when the activation cap is displaced proximally when the device is pressed against a subject’s skin to puncture the skin with the needle, the activation cap causing a spacer and release cap to also displace proximally to release a carriage carrying an opener pin, causing the opener pin to advance distally to open a gas canister to release pressurized gas into a flow path within the device.

[0016] FIGS. 5A-5C are details of the proximal end of the device as shown in FIGS. 4A-4C, respectively.

[0017] FIGS. 6A and 6B are cross-sections of the device of FIGS. 2A and 2B after the pressurized gas is released, showing the pressurized gas advancing a plunger within the device to deliver one or more agents within the syringe through the needle, and advancing the activation cap when the needle is withdrawn from the subject’s skin.

[0018] FIG. 6C is a detail of the device as shown in FIG. 6B, showing a tab locking the activation cap after being advanced.

[0019] FIGS. 7A and 7B are cross-sectional views of the device of FIGS. 1-6 showing the trigger force necessary to activate an opener mechanism of the device.

[0020] FIGS. 8A and 8B are cross-sections of another exemplary auto-injector device showing internal components of the device including a syringe carrying one or more agents.

[0021] FIGS. 8C-8E show various stages of activation of the injector device of FIGS. 8A and 8B.

[0022] The drawings are not intended to be limiting in any way, and it is contemplated that various examples of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of theinvention; it being understood, however, that this invention is not limited to the precise arrangements shown. DETAILED DESCRIPTION

[0023] Before the examples are described, it is to be understood that the invention is not limited to particular examples described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular examples only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0024] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0025] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, some potential and exemplary methods and materials are now described.

[0026] It must be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a compound” includes a plurality of such compounds and reference to “the polymer” includes reference to one or more polymers and equivalents thereof known to those skilled in the art, and so forth.

[0027] Certain ranges are presented herein with numerical values being preceded by the term “about.” The term “about” is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately aspecifically recited number, the near or approximating unrecited number may be a number which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number.

[0028] Turning to the drawings, FIG. 1 shows an example of an auto-injector device 6 that includes an outer housing 8 including a front housing 10 carrying a syringe 70 containing one or more agents within an agent chamber, and a rear housing 12 including a drive assembly for automatically delivering the agent(s) from the syringe 70 when the device 6 is activated. As shown, a safety cap 86 is provided on the front housing 10 to prevent premature activation of the device 6, which may be removed immediately before an injection, as described further elsewhere herein. One or more internal components of the device 6 may move axially, i.e., proximally and / or distally relative to the longitudinal axis 18 when the device 6 is activated, as described further elsewhere herein.

[0029] In one example, the syringe 70 may be a pre-filled syringe, e.g., formed from glass, plastic, and the like, filled with a predetermined volume of agent, e.g., corresponding to a single dose for a patient. Alternatively, the agent chamber and needle may be integrated into the front housing 10 if desired (not shown). In a further alternative, the syringe 70 (or integral agent chamber) may include a distal port (not shown) without a needle, such that a separate needle (also not shown) may be coupled to the port, e.g., using a Luer fitting, mating threads, and / or other cooperating connectors, immediately before an injection or otherwise as desired. As used herein, “agent” may include one or more flowable therapeutic and / or diagnostic compounds, medicaments, or materials, e.g., in liquid or gaseous form, in solution or suspension, and the like, such as viscous fluids.

[0030] Turning to FIGS 2A and 2B, an exemplary auto-injector device 6 is shown that includes an outer housing 8 including a front housing 10 carrying a syringe 70 containing one or more agents within an agent chamber 73, and a rear housing 12 including a drive assembly for automatically delivering the agent(s) from the syringe 70 when the device 6 is activated. As shown, a safety cap 86 is provided on the front housing 10 to prevent premature activation of the device 6, which may be removed immediately before an injection, as described further elsewhere herein. One or more internal components of the device 6 may move axially, i.e., proximally and / or distally relative to the longitudinal axis 18 when the device 6 is activated, as described further elsewhere herein.

[0031] In one example, the syringe 70 may be a pre-filled syringe, e.g., formed from glass, plastic, and the like, filled with a predetermined volume of agent, e.g., correspondingto a single dose for a patient. Alternatively, the agent chamber and needle may be integrated into the front housing 10 if desired (not shown). In a further alternative, the syringe 70 (or integral agent chamber) may include a distal port (not shown) without a needle, such that a separate needle (also not shown) may be coupled to the port, e.g., using a Luer fitting, mating threads, and / or other cooperating connectors, immediately before an injection or otherwise as desired. As used herein, “agent” may include one or more flowable therapeutic and / or diagnostic compounds, medicaments, or materials, e.g., in liquid or gaseous form, in solution or suspension, and the like, such as viscous fluids.

[0032] With continued reference to FIGS. 2A and 2B, the syringe 70 includes a barrel 72 containing the agent(s) within agent chamber 73, a needle 78 extending from a distal end 72a of the barrel 72, and a piston or stopper 74 slidable within a proximal end 72b of the barrel 72 for directing the agent(s) through the needle 78 into the subject’s body (not shown). The device 6 also includes a gas canister or other source of pressurized gas 40 to power the device 6, e.g., to advance a plunger 50 coupled to the piston 74 to deliver the agent(s). The device 6 also includes an activation cap 80 and an opening mechanism 60 for opening the canister 40 to release pressurized gas within the canister 40 into a set of chambers of the device 6. For example, an inner housing 20 may be mounted within the outer housing 8 that includes a first or proximal chamber 22, e.g., within which the gas canister 40 is mounted, and a second or distal chamber 24, e.g., in which the plunger 50 is slidably received.

[0033] Generally, the device 6 is configured such that, when a contact surface 84 of the activation cap 80 is pressed against a subject’s skin to insert the needle 78, the activation cap 80 retracts proximally into the outer housing 8 and automatically activates the opening mechanism 60 to release the pressurized gas from the canister 40 into the first and second chambers 22, 24, which generates a distal force to advance the plunger 50 to deliver the agent(s) from the syringe 70 into the subject. After the injection is completed and the device 6 is withdrawn away from the skin, the activation cap 80 may automatically advance to cover the needle 78.

[0034] For example, a spacer 30 may be provided that extends between the activation cap 80 and a release cap 34 of the opening mechanism 60, e.g., such that proximal movement of the activation cap 80 is translated by the spacer 30 to the direct the release cap 34 proximally within the rear housing 12, which releases a spring perch assembly or carriage 64 of the opening mechanism 60, as described further elsewhereherein. The spacer 30 may be biased distally, e.g., by spring 32, which may, in turn, bias the activation cap 80 distally after completing the injection, also as described further elsewhere herein.

[0035] Generally, the outer housing 8 includes a proximal end 8a, e.g., provided on the rear housing 12, an open distal end 8b, e.g., provided on the front housing 10, and an inner wall extending therebetween to enclose the interior of the device 6. The outer surface between the proximal and distal ends 8a, 8b may be sized and / or shaped to facilitate manipulation of the device 6, e.g., to facilitate placing and pressing the activation cap 80 against a subject’s skin to activate the device 6 and inject the agent(s). For example, the outer surface may have a generally cylindrical shape optionally including one or more textures or grip features to facilitate an operator (the subject themselves or a third party) holding the device 6 in one hand and pressing the activation cap 80 against the subject’s skin, as described further elsewhere herein. As shown, the proximal end 8a of the housing 8 may include a wall 8c enclosing the proximal end 8a and, optionally, one or more pockets or other features 8d for locking the release cap 34, as described further elsewhere herein.

[0036] The outer housing 8 may be formed from multiple, separate components, e.g., clamshell halves, e.g., formed from metal, such as stainless steel, aluminum, and the like, plastic, and / or composite material, by one or more of cold drawing, molding, casting, machining, and the like, that are substantially permanently attached together, e.g., by one or more of welding, soldering, fusing, bonding with adhesive, interference fit, and the like. As shown, the outer housing 8 is formed as separate forward and rear housings 10, 12, which may be assembled separately with respective internal components, and then coupled together, e.g., after loading a syringe 70 into the front housing 10.

[0037] For example, during manufacturing, the front housing 10 may be assembled with the activation cap 80 and safety cap 86, and a syringe 70 may be loaded into an interior of the front housing 10, e.g., during manufacturing or during assembly of the device 6 any time before performing an injection. Optionally, as shown in FIGS. 3A and 3B, the syringe 70 may include a rigid needle shield 79, e.g. formed from conventional materials, that may be removably secured to the distal end 72a of the barrel 72 to protect the needle and prevent accidental sticks. The safety cap 86 may include features 86a that engage the needle shield 79 such that, when the safety cap 86 is removed, the needle shield 79 is also removed. For example, as shown, the proximal end of the safety cap 86 may include one or more fingers 86a that fit into one or more corresponding cutouts, recesses, or other features on the needleshield 79 when the syringe 70 is inserted into the front housing 10, thereby coupling the needle shield 79 to the safety cap 86, as described elsewhere herein.

[0038] The rear housing 12 may be assembled with the inner housing 20, the spacer 30, the release cap 34, the gas canister 40, the plunger 50, and the opening mechanism 60 (and any other incidental components), and the rear housing 12 may be coupled to the front housing 10 at any time. For example, during manufacturing, a syringe 70 may be loaded into the interior of the front housing 10, and the assembled rear housing 12 may be immediately coupled to the front housing 10. When the rear housing 12 is attached to the front housing 10, a distal end 54 of the plunger 50 may be coupled to the piston 74 within the syringe 70, e.g., such that distal movement of the plunger 50 is translated to the piston 74, as described further elsewhere herein.

[0039] As shown in FIGS. 2A and 2B, the outer housing 8 may include a mount 11, e.g., on one of the forward and rear housings 10, 12, for guiding and / or securing the syringe 70 during loading. Optionally, the proximal end 72b of the barrel 72 may include one or more flanges, e.g., a radial flange or a pair of opposing flanges, that may abut and / or be received within the mount 11 to secure the syringe 70 relative to the front housing 10. In addition or alternatively, one or more detents, ridges, or other features (not shown) may be provided on the front housing 10 for securing the syringe 70. Optionally, the front housing 10 may include one or more windows 10c in the sidewall, which may facilitate observing the syringe 70 during an injection, e.g., to allow visual confirmation when the piston 74 is fully advanced.

[0040] Optionally, the device 6 may include a syringe spacer or adapter 75 that may provide an interface between a distal end 54 of the plunger 50 and the piston 74, e.g., to provide connectors therebetween and / or ensure proper spacing such that the piston 74 is advanced in conjunction with the plunger 50. For example, different length spacers 75 may be provided to allow different length syringes to be loaded into the front housing 10 while properly positioning the needle 78 adjacent the distal end 8b of the outer housing 8 and allowing the plunger 50 to be properly coupled to the piston 74.

[0041] During manufacturing or assembly, a syringe 70 may be selected that may be inserted into the housing 8, e.g., through the opening in the distal end 8b and coupled to the distal end 16 of the drive assembly 12. A syringe spacer 75 may be selected and its distal end 75a may be coupled to the piston 74, e.g., by one or more cooperating threads, as shown, one or more detents or other connectors, and the like. The distal end 54 of theplunger 50 may be inserted into a recess 75b in the syringe spacer 75 when the rear housing 12 is coupled to the front housing 10. Optionally, the distal end 54 of the plunger 50 and the recess 75b may include cooperating locking features, e.g., one or more threads, detents, and the like (not shown) or the distal end 54 may simply be inserted into the recess 75b to coupled subsequent distal movement of the piston 74 to the plunger 50, as described further elsewhere herein.

[0042] Alternatively, the assembled housings 10, 12 may be packaged, stored, and / or otherwise prepared for subsequent assembly. For example, the housing 10, 12 may be shipped or otherwise provided to a manufacturer of the syringe 70, who may load the syringe 70 and couple the housings 10, 12 together to provide the finished device 6. In a further alternative, the assembled housings 10, 12 may be provided to a hospital, physician, or other medical professional, and final assembly may be completed immediately before performing an injection, which may allow a syringe including a specific agent to be loaded before an injection.

[0043] The proximal end 10a of the front housing 10 and the distal end 12b of the rear housing 12 may include one or more cooperating connectors (not shown) to couple the housings 10, 12 together to provide the fully-assembled device 6. For example, the housings 10, 12 may include one or mating threads, detents, and the like, which may permanently couple the housings 10, 12 together. Alternatively, the connectors may allow the housings 10, 12 to be subsequently separated, e.g., after performing an injection, to remove the syringe 70, e.g., to allow the device 6 to be cleaned and reused with a new syringe.

[0044] In addition or alternatively, the housings 10, 12 may be permanently attached together by one or more of an interference fit between the ends 10a, 12b, bonding with adhesive, fusing, sonic welding, and the like. In another alternative, the outer housing 8 may be formed as a single, integral component into which the components of the device 6 may be assembled. In these alternatives or even with a two-part housing, the device 6 may be a single use device, which may be disposed of after a single injection.

[0045] In the example shown in FIGS. 2A and 2B, the inner housing 20 includes a proximal cylinder 20a including the first chamber 22 and a distal cylinder 20b including the second chamber 24. Each of the proximal and distal cylinders 20a, 20b may have an elongate cylindrical wall or other cross-sectional shape along their lengths. The proximal and distal cylinders 20a, 20b may be permanently attached together to provide the innerhousing 20, e.g., by one or more of cooperating threads, as shown, detents or other connectors, force fit, bonding with adhesive, sonic welding, fusing, and the like. Alternatively, the inner housing 20 may be formed as a single, unitary structure including the first and second chambers 22, 24. The proximal and distal cylinders 20a, 20b may be formed from materials similar to or different from the outer housing 8.

[0046] The inner housing 20 may be mounted within the outer housing 8 such the inner housing 20 remains substantially stationary within the outer housing 8. Similarly, the gas canister 40 may be mounted within the inner housing 20, e.g., within the first chamber 22, such that the gas canister 40 also remains substantially stationary relative to the outer housing 8. For example, one or more struts, supports, or other structures (not shown) may be provided on the inner and / or outer housings 20, 8 to secure the inner housing 20 and / or the gas canister 40 relative to the outer housing 8.

[0047] In the example shown, the proximal cylinder 20a may include an annular wall surrounding the first chamber 22 that includes a uniform diameter first region 22a within which the gas canister 40 is mounted, and second and third regions 22b, 22c within which the carriage 64 is slidably mounted, as described further elsewhere herein. The distal cylinder 20b may have a length such that a distal end 21b of the distal cylinder 20b may abut the syringe 70 when the device 6 is assembled.

[0048] Optionally, the distal end 21b may include one or more features that contact the proximal end 72b of the syringe 70, e.g., an O-ring 20d secured on or around the distal end 21b formed from resilient and / or relatively flexible material. The O-ring 20d may prevent the distal end 21b from damaging the syringe 70, e.g., if the barrel 72 is made from glass.

[0049] With continued reference to FIGS. 2A and 2B, the canister 40 includes a body 42 including a first closed end 42a, a second outlet end 42b, and a cap 44 welded or otherwise attached to the outlet end 42b to provide an enclosed cavity 48 filled with a fluid containing pressurized gas, such as carbon dioxide or fluorocarbon gases, compressed to sufficient pressure to least partially liquefy the gas within the cavity 48. Alternatively, fluids containing gases such as argon, nitrogen, helium, or other combinations thereof that remain in gaseous form may be stored within the cavity 48. As described elsewhere herein, the pressurized fluid contained within the cavity 48 may be used to generate the forces to operate the device 6, e.g., to inject one or more agents from the syringe 70 into a subject’s body.

[0050] In one example, the body 42 and cap 44 may be formed from stainless steel or other desired or suitable metal, plastic, or composite material, e.g., formed by one or more of drawing, stamping, machining, casting, molding, and the like. For example, the body 42 may be deep drawn from sheet metal, e.g., a round sheet metal blank of Type 305 stainless steel, using one or more dies and punches (not shown), to form a main barrel region, the enclosed end 42a, an optional tapered shoulder region, and the outlet end 42b defining an opening to which the cap 44 is attached.

[0051] As shown, the canister 40 may be oriented with the outlet end 42b proximal to the enclosed end 42a, and the carriage 64 may be provided proximal to the outlet end 44. In the example shown, the cap 44 may be an enclosed cap including an outlet, weakened region, or other outlet (not shown) that may be opened by the opening mechanism. In this example, the carriage 64 may include an opener pin 62 configured to puncture or preferentially tear the septum, as described elsewhere herein. Additional information regarding canisters that may be used and methods for making them may be found in U.S. Publication No. 2017 / 0258583, the entire disclosure of which is expressly incorporated by reference herein.

[0052] Alternatively, the cap 44 may include other closer mechanisms, such as a ball or other member (not shown) that may be biased or otherwise configured to close an outlet in the cap 44 yet may be directed away from the cap 44, e.g., into the canister 40, by the carriage 64 to open the outlet and release the pressurized gas within the cavity 48. In this alternative, the opener pin 62 may include a tapered tip (not shown) sized to enter the outlet and push the closure away from the outlet.

[0053] The plunger 50 may be an elongate rod or other member including a proximal end 52 that is slidably disposed within the second chamber 24, e.g., initially immediately adjacent the first chamber 22, and a distal end 54 coupled to the piston 74. The plunger 50 is movable from an initial or retracted position (e.g., shown in FIGS. 2A and 2B) to a final or extended position (e.g., shown in FIGS. 6A and 6B), e.g., wherein the distal end 54 extends from the second end 16 of the drive assembly 12 into the agent chamber 73 of the syringe 70.

[0054] A flange or other guide member 53 may be provided on the proximal end 52 of the plunger 50 that slidably engages a wall of the second chamber 24. Consequently, when pressurized gas enters the second chamber 24 (via the first chamber 22), the pressure generates a distal force to direct the plunger 50 distally from the initial position towards theextended position to advance the piston 74 and deliver the one or more agents from the agent chamber 73 through the needle 78 into the subject, as described further elsewhere herein.

[0055] Optionally, a wall, orifice, or intermediate passage (not shown) may be provided between the first and second chambers 22, 24. The intermediate passage may have a relatively small diameter to provide a restrictor to reduce pressure rise time within the second chamber 24. For example, the intermediate passage may i) slow down the transient flow of gas, slowing the rise of pressure imparted to the plunger 50, e.g., providing a soft-start to the injection, reducing / eliminating pressure shock waves in the fluid to be injected in the syringe and possibly reducing patient pain as the drug injection is gently initiated; and / or ii) slow down the steady state flow of gas, reducing the otherwise pressure imparted to the plunger 50, providing a limiting effect to the flow rate of the drug injected into the patient.

[0056] Optionally, as shown, the plunger 50 may also include a plunger chamber 56, e.g., extending from an open proximal end 52 of the plunger 50 to a closed distal end 54. The plunger chamber 56 may taper inwardly from the proximal end 52 to the distal end 54, as shown, or may have a uniform diameter or other cross-sectional shape along its length. Alternatively, the proximal end 52 of the plunger 50 may include a closed wall and / or the plunger 50 may be a solid rod between the proximal and distal ends 52, 54.

[0057] Optionally, the flange 53 on the proximal end 52 of the plunger 50 may include one or more passages (not shown) that extend between proximal and distal surfaces of the flange 53. For example, the flange 53 may include a plurality of circular or other enclosed passages spaced apart from one another around a circumference of the flange 53, each extending between the proximal and distal surfaces.

[0058] In this option, the flange 53 may be sized and / or shaped to slidably engage an inner wall of the second chamber 24, e.g., to allow the plunger 50 to move from the initial to the extended position, but may not require O-rings or other seals. Instead, one or more O-rings or other seals may be provided within and / or adjacent the inner housing 20 to seal the first and second chambers 22, 24 and / or otherwise a flow path from the gas canister 40 to the plunger 50. For example, a first O-ring 58a may be provided between the inner housing 20 and the carriage 64, a second O-ring 58b may be provided between a distal end 21b of the inner housing 20 and the plunger 50, and / or a third O-ring 58c may be providedbetween the proximal and distal cylinders 10a, 10b, if provided as separate components secured together.

[0059] In one example, the plunger 50 includes a flange 53 formed as a cylindrical head having a larger outer diameter than the plunger 50, which may be integrally molded or otherwise formed with the plunger 50, or that is manufactured separately and permanently attached to the plunger 50, with one or more passages (not shown) extending between the proximal and distal surfaces of the flange 53. When the canister 40 is opened to release the pressurized gas, the initial volume that the gas must fill the first chamber 22 around the canister 40, the second chamber 24 around the plunger 50 and, optionally, the plunger chamber 56, which may result in an initial pressure drop as the gas fills the available volume. However, as the plunger 50 advances, the change in volume that the gas must fill increases only minimally (e.g., the volume the plunger 50 occupies within the second chamber 24 that is displaced out of the distal end 16 of drive assembly 12). Consequently, because the volume change is minimized, the resulting force applied by the pressure on the plunger 50 may remain substantially constant or reduce only slightly. Thus, the resulting force drop applied to the plunger 50 may be minimized, which may provide a more uniform delivery rate of the agent from the syringe 70. Additional information regarding plungers that may provide reduced pressure drop can be found in co-pending U.S. application, Serial Nos. 17 / 965,707, the entire disclosure of which is expressly incorporated by reference herein.

[0060] Optionally, the proximal end 52 of the plunger 50 may have a larger diameter or other cross-section than the distal end 54 of the plunger 50. For example, the outer diameter or cross-section may taper between the proximal and distal ends 52, 54 of the plunger 50. Such a tapered shape may increase the cross-sectional area of the plunger 50 as it advances from the initial position towards the extended position, which may minimize the change in the distal force applied to the syringe stopper due to volume change, which may be particularly useful for applications where consistent rates of delivery are desired. It will be appreciated that any of these optional features related to the plunger 50 may be combined together or omitted, as desired.

[0061] Returning to FIGS. 2A and 2B, the opening mechanism 60 includes a release cap 34 and a spring perch assembly or carriage 64 slidably coupled to the rear housing 12, e.g., within the second and third regions 22b, 22c of the first chamber 24. The carriage 64 carries the opener pin 62, e.g., mounted along the axis 18 and oriented distally towards thecap 44. The carriage 64 and release cap 34 include one or more features that disengage when the release cap 34 is directed proximally (by the activation cap 80 and spacer 30), and the carriage 64 may be biased to move distally, when released, to direct the opener pin distally to open the outlet in the cap 44 of the canister 40.

[0062] For example, the rear housing 12 and the carriage 64 may include cooperating features that prevent the carriage 64 from moving until the device 6 is activated. For example, as best seen in FIGS. 5A-5C, the carriage 64 includes locking tabs or other features 64a on its proximal end that engage the proximal end 13a of the rear housing 12, and a flange 64b on its distal end slidable within the second region 22b of the first chamber 24. A puncture spring 66 is also provided within the second region 22b around the carriage 64, e.g., a coil spring provided in an initially compressed state between the rear housing 12 and the flange 64b. Consequently, the spring 66 biases the carriage 64 to move distally, but for the locking features 64a engaging the proximal end 13a of the rear housing 12.

[0063] The release cap 34 and carriage 64 include cooperating features that release the locking features 64a from the rear housing 12 when the device 6 is activated. For example, as shown in FIGS. 5A-5C, the release cap 34 includes a cylindrical body surrounding a portion of the rear housing 12, e.g., around the second and third regions 22b, 22c of the first chamber 24. The release cap 34 may also include an enclosed proximal end 34a proximal to the proximal end 13a of the rear housing 12, and a distal end 34b that includes one or more features to limit axial movement of the release cap 34. For example, one or more flanges on the distal end 34b may slide proximally along the inner surface of the outer housing 8, e.g., until they abut a ridge on the outer housing 8 to prevent further proximal movement of the release cap 34, as described further elsewhere herein.

[0064] As shown, a central hub 36 is provided on the proximal end 34a of the release cap 34 aligned along the axis 18 distally towards the opener pin 62. The carriage 64 includes a plurality of tabs or release fingers 65, e.g., arranged concentrically around the axis 18 such that the tabs 65 may slide along the hub 36 as the release cap 34 is directed proximally. Once the hub 36 moves proximally beyond the tabs 65, the tabs 65 are biased to move radially inwardly (towards the central axis 18), thereby directing the locking features 64a inwardly. Once the locking features 64a clear the proximal end 13a of the rear housing 12, e.g., as shown in FIG. 5C, the spring 66 may automatically direct the carriage 64 distally, thereby directing the opener pin 62 distally to penetrate the septum in the cap 44 of the canister 40 (or otherwise opening the outlet).

[0065] During use, the device 6 may be provided initially with the safety cap 86 attached to the distal end 8b of the housing 8, e.g., as shown in FIGS. 1-2B. Immediately before performing an injection, the safety cap 86 may be removed, e.g., by simply pulling the safety cap 86 distally away from the outer housing 8, to expose the contact surface 84 of activation cap 80, e.g., as shown in FIG. 4A. For example, as best seen in FIGS. 3A and 3B, the safety cap 86 may include inner and outer cylindrical members with the proximal end 86a of the inner member coupled to the needle shield 79 and a proximal end 86b of the outer member slidably received over the distal end 8b of the outer housing 8. Alternatively, the safety cap 86 and / or outer housing 8 may include one or more connectors, locks, and the like (not shown) that may be disengaged before removing the safety cap 86.

[0066] As described elsewhere herein, the safety cap 86 may prevent the activation cap 80 from being directed proximally, e.g., by preventing the activation cap 80 from being contacted. In addition or alternatively, the safety cap 86 may include features that engage the needle shield 79 such that, when the safety cap 86 is removed, the needle shield 79 is also removed. The safety cap 86 and needle shield 79 may prevent the needle 78 from being exposed from the housing 8 prior to use. Once the safety cap 86 and needle shield 79 are removed, the device 6 is ready to be used to perform an injection.

[0067] Turning to FIGS. 4A-4C, the contact surface 84 may be placed against a subject’s skin (not shown) and then the device 6 may be pressed against the skin to insert the needle 78, thereby causing the activation cap 80 to slide proximally from the initial position shown in FIG. 4A to the retracted position shown in FIG. 4B as the needle 78 enters the subject’s skin. As described further below, this action may activate the opening mechanism 60 to cause the opener pin 62 to open the outlet of the gas canister 40 to release pressurized gas into the first chamber 22, whereupon the pressurized gas may advance the plunger 50 and, consequently, the piston 74 to deliver the agent(s) through the needle 78 into the subject.

[0068] For example, as shown in FIG. 4A, initially, the proximal end 82 of the activation cap 80 may abut or otherwise engage a distal end 30a of the spacer 30, and a proximal end 30b of the spacer 30 may abut or otherwise engage the distal end 34b of the release cap 34. Consequently, when the activation cap 80 is retracted proximally within the outer housing 8, its proximal end 82 pushes the distal end 30a of the spacer 30, thereby directing the spacer 30 proximally, and, in turn, the proximal end 30b of the spacer 30 pushes the distal end 34b of the release cap 34, thereby directing the release cap 34proximally, e.g., until the proximal end 34a of the release cap 34 contacts the proximal end 8c of the outer housing 8.

[0069] As the activation cap 80, spacer 30, and release cap 34 move proximally, the inner housing 20 (and canister 40 within the first chamber 22) may remain substantially stationary. As can be seen in FIGS.4A and 4B, as the spacer 30 is directed proximally, the spring 32 may be compressed, e.g., between features on the distal end 30a of the spacer 30 and the inner housing 20, thereby biasing the spacer 30 subsequently to move distally. However, with the operator pressing the contact surface 84 of the activation cap 80 against the subject’s skin, the spacer 30 is unable to move distally.

[0070] Since the carriage 64 is secured relative to the inner housing 20 by the locking features 64a, the carriage 64 also remains substantially stationary, such that the release cap 34 moves proximally relative to the carriage 64 and the tabs 65 on the carriage 64 slide along the hub 36 on the release cap 34, as best seen in FIGS. 5A-5C. When the release cap 34 reaches its proximal-most position, e.g., shown in FIGS. 4C and 5C, the hub 36 has moved proximally beyond the ends of the tabs 65 and, given the inward bias of the tabs 65, the tabs 65 are released and automatically move inwardly. Given that the tabs 65 are coupled to the locking features 64a on the carriage 64, the inward movement of the tabs 65 causes the locking features 64a to move inwardly, thereby disengaging the locking features 64a from the proximal end 21a of the inner housing 20.

[0071] Due to the spring 66, the carriage 64 is then released and biased to move distally, thereby advancing the opener pin 62 distally to open the outlet of the canister 40, as shown in FIGS. 4C and 5C. The release cap 34 may include one or more tabs or other features 34c, e.g., corresponding to the pockets 8d in the outer housing 8, such that, when the release cap 34 reaches its proximal-most position, the tabs 34c are received in respective pockets 8d, as shown. Thus, the tabs 34c may prevent the release cap 34 from moving distally as the carriage 64 advances distally due to the spring 66.

[0072] When the carriage 64 moves distally, it causes the opener pin 62 to advance and penetrate the septum in the cap 44 (or otherwise open the outlet), thereby releasing the pressurized gas within the canister 40. The released pressurized gas then enters the first chamber 22, e.g., around the canister 40, and passes to the second chamber 24, thereby pressurizing the second chamber 24 to generate a distal force to direct the plunger 50 distally from the initial position towards its extended position to deliver the one or more agents from the syringe 70 through the needle 78 into the subject, e.g., as shown in FIG. 6A.

[0073] The operator may monitor the syringe 70 during the injection, e.g., via the window(s) 8c to confirm that the piston 74 has fully advanced distally within the barrel 72 to deliver the entire dose into the subject. Once the injection is completed, the device 6 may be directed away from the subject, thereby withdrawing the needle 78 from the subject’s skin. As the device 6 is directed away from the subject’s skin, the activation cap 80 is free to move distally and, due to the distal bias of the spring 32, the spacer 30 automatically advances distally, thereby directing the activation cap 80 distally to cover the needle 78 as it is withdrawn.

[0074] As best seen in FIG. 6C, as the spacer 30 advances distally, the proximal end 30b of the spacer may pass distally beyond features 34d on the distal end 34b of the release cap 34. For example, the features 34b may include one or more fingers or tabs that slide along the interior of the spacer 30 until the proximal end 30b passes distally, whereupon the tabs may resiliently move radially outwardly, e.g., such that the tabs 34d are located proximal to the proximal end 30b of the spacer 30, thereby preventing the spacer 30 from subsequently moving proximally. With the spacer 30 prevented from moving proximally, the activation cap 80 is unable to retract again, thereby locking the activation cap 80 extended over the needle 78 and preventing accidental exposure of the needle 78.

[0075] If the device 6 is a single-use device, the device 6 may then be disposed of. If the device is reusable, e.g., if the forward and rear housings 10, 12 are separable, the rear housing 12 may subsequently be separated from the front housing 10, and the syringe 70 may be removed. For a reusable device, one or more features may be provided within the device to release any residual pressure within the first and second chambers 22, 24. For example, as shown in FIGS. 6A and 6B, a gas valve and / or shaft member may be provided within the plunger 50, which may be manipulated to release the pressurized gas before removing decoupling the plunger 50 from the piston 74. The separate housings 10, 12 may then be cleaned and / or sterilized and a new gas canister 40 may be loaded into the inner housing 20 before reassembling the device.

[0076] Turning to FIGS. 7A and 7B, as described above, the device 6 includes a cylinder spacer 30 operatively coupled between the activation cap 80 and the release cap 34 of the opener mechanism. As shown, the spacer 30 is biased distally by an activation cap return spring 32, which biases the spacer 30 and, consequently, the activation cap 80, distally after completing an injection. For example, as the activation cap 80, spacer 30, and release cap 34 move proximally from the initial position shown in FIG. 7A, e.g., when theactivation cap 80 is pressed against a patient’s skin, the inner housing 20 (and canister 40 within the first chamber 22) remains substantially stationary. Consequently, as can be seen in 7B, as the spacer 30 is directed proximally, the spring 32 is compressed, e.g., between features 30c, 20c on the distal end 30a of the spacer 30 and on the inner housing 20, thereby biasing the spacer 30 subsequently to move distally, e.g., when the activation cap 80 is release after performing an injection.

[0077] One disadvantage of this configuration is that the activation force required to activate the device 6 is the sum of the spring force required to compress the activation cap return spring 32 and the trigger force to activate the opener mechanism, i.e., the force required to direct the release cap 34 proximally to disengage the release fingers 65 on the carriage 64 from the hub 36 on the release cap 34. For example, as the activation cap 80 is pressed against a patient’s skin, the user must overcome the bias of the return spring 32 acting on the spacer 30 (and consequently, the activation cap 80). Further, as potential energy is stored in the return spring 32, this potential energy applies a constant (and increasing) distal force on the spacer 30 and activation cap 80, which the user must overcome. This is in addition to the force the user must apply to cause the spacer 30 to direct the release cap 34 proximally until the carriage 64 is released, e.g., to overcome the friction and / or other forces between the release fingers 166 and hub 136. Thus, it may be desirable to reduce the force required to activate the device 6, e.g., to reduce the resistance a user may feel and / or distal force the user must apply when pressing the activation cap 80 against a patient’s skin to perform an injection.

[0078] One option to reduce the activation force would be to separate the cylinder spacer into two different parts or segments, where a first segment is an extension of a release cap of an opener mechanism to provide a trigger component while a second segment may be coupled to the activation cap as a user interface component. The return spring may be coupled between the spacer segments rather than the inner housing. Consequently, the force acting to compress the return spring when the activation cap is pressed against a patient’s skin may be stored and later used to activate an opener or trigger mechanism once the spring force is equal to the trigger force.

[0079] For example, turning to FIGS. 8A-8E, an example of an injector device 106 is shown, which may include many components that are similar to the device 6, e.g., including an injector module carrying a syringe 70 and a drive module including an inner housing 120. The inner housing 120 includes a first or proximal chamber 122 within whicha gas canister 40 and opener mechanism (e.g., including a release cap 134 and a carriage 164 carrying an opener pin 162) may be provided. The inner housing 120 also includes a second or distal chamber 124 within which a plunger 150 is slidably received such that, when the opener mechanism is activated, the opener pin 162 opens an outlet of the canister 40, and pressurized gas is released, which then passes from the first chamber 122 into the second chamber 124 to advance the plunger 150. The device 106 also includes an activation cap 180, which initially covers a needle 78 of the syringe 70, as shown in FIG. 8A, all of which may be generally constructed and / or configured similar to like components of the device 6.

[0080] The device 106 also includes a cylinder spacer 130 that is operatively coupled between the activation cap 180 and the release cap 134. However, unlike the device 6, the spacer 130 is operatively coupled to a spacer extension 138 on the release cap 134, e.g., a tubular body that is integrally formed or attached to the release cap 134 such that the spacer extension 138 extends around the inner housing 120 towards the spacer 130. A return spring 132 is provided around the inner housing 120, e.g., around the second chamber 124, which may be coupled between the spacer 130 and the spacer extension 138.

[0081] For example, as shown, the return spring 132 may be a compression spring that is positioned between one or more features 130c, 138c on the spacer 130c and spacer extension 138. The features 130c, 138c may include a continuous annular ledge on the spacer 130c and spacer extension 138 or one or more tabs spaced apart around the circumference of the spacer 130 that cause the return spring 132 to compress axially therebetween when the spacer 130 is moved proximally, e.g., when the activation cap 180 is directed proximally, as shown in FIG. 8B.

[0082] Thus, unlike the device 6 where the return spring 32 is coupled between a movable part (the spacer 30) and a stationary part (the inner housing 20), the return spring 132 is coupled between two movable parts, i.e., the spacer 130 and spacer extension 138 of the release cap 134.

[0083] During use of the device 106, the activation cap 180 may be initially provided in its distal, advanced position covering the needle 78, as shown in FIG. 8A. When a contact surface 184 of the activation cap 180 is pressed against a patient’s skin to insert the needle 78, the activation cap 180 begins to retract proximally into the device 106, thereby directing the spacer 130 proximally and compressing the return spring 132 between the spacer 130 and the spacer extension 138.

[0084] As the return spring 132 is compressed, potential energy increases to generate a spring force that acts proximally on the spacer extension 138, and consequently, the release cap 134, since the spacer 130 and activation cap 180 cannot move distally. As shown in FIG. 8B, when this spring force exceeds a trigger force required to move the release cap 134 relative to the carriage 164, the release cap 134 displaces proximally, as represented by arrow A1. For example, as described elsewhere herein, the trigger force may include friction and / or other forces acting between the release fingers 166 on the carriage 164 and the hub 136 on the release cap 134, which must be overcome to move the release cap 134 proximally.

[0085] As shown in FIGS. 8C and 8D, when the spring force exceeds the trigger force, the release cap 134 displaces proximally until the release fingers 166 are disengaged from the hub 136, thereby releasing the carriage 164. The carriage 164 is then free to move distally (due to its distal bias) to direct the opener pin 162 to open the outlet of the canister 40, thereby releasing the pressurized gas therein, as shown in FIG. 8E. The gas may then pass through the first chamber 122 into the second chamber 124, thereby applying a distal force that advances the plunger 150, and consequently, the piston 74 to deliver the one or more agents within the agent chamber 73 of the syringe 70, generally similar to the device 6. Given that only the trigger force needs to be overcome to activate the device 106, the user may not experience excessive forces from compression of the return spring 132. This may provide a more intuitive and / or easier to use injector device 106, as compared to the device 6. It will be appreciated that this configuration may be used in any of the injector devices disclosed in the patents incorporated by reference herein.

[0086] While the invention is susceptible to various modifications, and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents and alternatives falling within the scope of the appended claims.

Claims

WE CLAIM:

1. A device for delivering one or more agents into a subject’s body, comprising: an outer housing comprising a proximal portion terminating in a proximal end and a distal portion terminating in a distal end; a syringe comprising a barrel within the distal portion containing one or more agents, a needle extending distally from the barrel such that a tip of the needle extends from the distal end, and a piston within a proximal end of the barrel; an activation cap on the distal end of the housing initially positioned such that a contact surface thereof is disposed distal to the distal end and the activation cap covers the needle, the activation cap movable proximally relative to the outer housing to expose the needle when the contact surface is pressed against the subject’s skin to insert the needle; an inner housing within the outer housing proximal portion comprising a first chamber adjacent the outer housing proximal end and a second chamber; a canister containing of pressurized gas within the first chamber; a release cap within the proximal portion adjacent the proximal end and coupled to a carriage carrying an opener pin positioned adjacent an outlet of the canister; a spacer within the outer housing comprising a first end operatively coupled to the activation cap such that the spacer moves proximally when the activation cap moves proximally; a return spring operatively coupled between the spacer and the release cap such that, when the activation cap and spacer move proximally, the return spring is compressed by the spacer to apply a proximal spring force on the release cap and, when the spring force is greater than a trigger force preventing movement of the release cap, the release cap moves proximally to release the carriage, whereupon the carriage causes the opener pin to open the outlet and release the pressurized gas; and a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe, wherein, when the pressurized gas is released from the canister, the pressurized gas passes from the first chamber into the second chamber to apply a distal force to advance the plunger to direct the piston distally to deliver the one or more agents through the needle.

2. The device of claim 1, wherein the return spring is configured to apply a distal force to the spacer when compressed such that, when the activation cap is movedaway from the subject’s skin, the spacer moves distally to automatically advance the activation cap to cover the needle.

3. The device of claim 1, wherein the activation cap comprises an activation cap extension that extends proximally from the activation cap to contact the first end of the spacer such that proximal movement of the activation cap causes the activation cap extension to push proximally on the first end of the spacer to move the spacer proximally.

4. The device of claim 1, wherein the release cap and carriage comprising one or more features that disengage when the release cap is directed proximally by the spring force, the carriage biased to move axially when released to move the opener pin to open the outlet.

5. The device of claim 4, wherein the inner housing and the carriage comprise cooperating features that prevent the carriage from moving proximally when the release cap is directed proximally.

6. The device of claim 4, further comprising an opener spring mounted between the carriage and the inner housing to bias the carriage to move axially.

7. The device of claim 4, wherein the one or more features comprise a central hub on the release cap and a plurality of release fingers or tabs on the carriage that slide along the hub as the release cap is directed proximally until the hub moves proximally beyond the release fingers or tabs.

8. The device of claims 7, wherein the trigger force comprises a static friction that is overcome to cause the release fingers or tabs to slide along the hub.

9. The device of claim 7, wherein the release fingers or tabs are biased to move radially inwardly to release the carriage.

10. The device of claim 7, wherein the carriage comprises one or more locking features that engage the inner housing to prevent the carriage from moving relative to theinner housing, the locking features coupled to the release fingers or tabs such that, when the release fingers or tabs move radially inwardly, the one or more locking features disengage from the inner housing, whereupon the carriage is released to move axially.

11. The device of any one of claims 1-10, wherein, when the activation cap moves proximally, a potential force in the return spring increases as the spacer is directed proximally to provide the spring force on the release cap until the potential force exceeds the trigger force, whereupon the release cap is directed proximally to release the opener pin.

12. A device for delivering one or more agents into a subject’s body, comprising: an outer housing comprising a proximal portion terminating in a proximal end and a distal portion terminating in an open distal end; a syringe comprising a barrel containing one or more agents, a needle extending distally from the barrel such that a tip of the needle is disposed within the distal portion adjacent the distal end, and a piston within a proximal end of the barrel; an inner housing within the outer housing comprising a first chamber adjacent the outer housing proximal end and a second chamber between the first chamber and the barrel proximal end; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the outer housing distal end and an activation cap extension extends proximally around the barrel; a source of pressurized gas within the first chamber; a release cap within the outer housing adjacent the outer housing proximal end carrying an opener pin located adjacent the source of pressurized gas; a spacer adjacent the inner housing within the outer housing comprising a distal end adjacent a proximal end of the activation cap extension and a proximal end adjacent the release cap; a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe; the activation cap movable proximally relative to the outer housing such that, when the contact surface of the activation cap is pressed against a subject’s skin to insert the needle, the activation cap moves proximally to direct the spacer proximally, the spacer consequently directing the release cap proximally to release the opener pin, thereby causingthe opener pin to open the source of pressurized gas to release the pressurized gas into the first chamber and into the second chamber such that the pressurized gas advances the plunger to direct the piston distally to deliver the one or more agents through the needle; and a biasing mechanism configured to bias the spacer to advance distally such that, when the activation cap is released when the contact surface is directed away from the subject’s skin after delivering the one or more agents, the spacer directs the activation cap distally to cover the needle, the biasing mechanism configured to apply spring force on the release cap when the activation cap and spacer are directed proximally is greater than a trigger force required to direct the release cap proximally to release the opener pin.

13. The device of claim 12, wherein the biasing mechanism comprises a return spring disposed around the inner housing between the spacer and an extension of the release cap such that a spring force generated by the return spring when the activation cap and spacer are directed proximally acts on the release cap to direct the release cap proximally when the spring force is greater than the trigger force.

14. The device of claim 12, further comprising a carriage releasably coupled to the release cap, the opener pin extending axially from the carriage, the release cap and carriage comprising one or more features that disengage when the release cap is directed proximally by the activation cap and spacer, the carriage biased to move axially when released to move the opener pin to open the outlet.

15. The device of claim 14, wherein the trigger force comprises a static friction required to disengage the one or more features.

16. The device of claim 14, wherein the inner housing and the carriage comprise cooperating features that prevent the carriage from moving proximally when the release cap is directed proximally.

17. The device of claim 14, further comprising an opener spring mounted between the carriage and the inner housing to bias the carriage to move axially.

18. The device of claim 14, wherein the one or more features comprise a central hub on the release cap and a plurality of release fingers or tabs on the carriage that slide along the hub as the release cap is directed proximally until the hub moves proximally beyond the release fingers or tabs, the trigger force comprising a static friction that is overcome to cause the release fingers or tabs to slide along the hub.

19. The device of claim 18, wherein the release fingers or tabs are biased to move radially inwardly to release the carriage.

20. The device of claim 18, wherein the carriage comprises one or more locking features that engage the inner housing to prevent the carriage from moving relative to the inner housing, the locking features coupled to the release fingers or tabs such that, when the release fingers or tabs move radially inwardly, the one or more locking features disengage from the inner housing, whereupon the carriage is released to move axially.

21. The device of any one of claims 12-20, wherein, when the activation cap moves proximally, a potential force in the return spring increases as the spacer is directed proximally to provide the spring force on the release cap until the potential force exceeds the trigger force, whereupon the release cap is directed proximally to release the opener pin.

22. A device for delivering one or more agents into a subject’s body, comprising: an outer housing comprising a proximal portion terminating in a proximal end and a distal portion terminating in an open distal end; a syringe comprising a barrel containing one or more agents, a needle extending distally from the barrel such that a tip of the needle is disposed within the distal portion adjacent the distal end, and a piston within a proximal end of the barrel; an inner housing within the outer housing comprising a first chamber adjacent the outer housing proximal end and a second chamber between the first chamber and the barrel proximal end; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the outer housing distal end and an activation cap extension extends proximally around the barrel;a source of energy within the first chamber; a release cap within the outer housing operatively coupled to the source of energy; a spacer adjacent the inner housing within the outer housing comprising a distal end adjacent a proximal end of the activation cap extension and a proximal end adjacent the release cap; a plunger comprising a proximal end within the second chamber and a distal end coupled to the piston of the syringe; the activation cap movable axially relative to the outer housing such that, when the contact surface of the activation cap is pressed against a subject’s skin, the activation cap moves proximally to direct the spacer proximally, the spacer consequently directing the release cap proximally to release energy from the source of energy, thereby advancing the plunger to direct the piston distally to deliver the one or more agents through the needle; and a biasing mechanism configured to bias the spacer to advance distally such that, when the activation cap is released when the contact surface is directed away from the subject’s skin after delivering the one or more agents, the spacer directs the activation cap distally to cover the needle, wherein, when the force generated by the biasing mechanism when the activation cap and spacer are directed proximally is greater than a trigger force required to direct the release cap proximally, the release cap moves to release the energy from the energy source.

23. The device of claim 22, wherein the source of energy comprises a source of pressurized gas within the first chamber, and wherein the release cap comprises an opener pin located adjacent the source of pressurized gas such that, when the release cap moves proximally, the opener pin is released, thereby causing the opener pin to open the source of pressurized gas to release the pressurized gas into the first chamber and into the second chamber such that the pressurized gas advances the plunger to direct the piston distally.

24. The device of claim 22, wherein the source of energy comprises a spring that is released when the release cap moves proximally to advance the plunger.

Images