Drive systems for auto-injectors, auto-injector devices, and methods for using them

Abstract

Drive modules and auto-injectors include a housing comprising first and second chambers therein; an opener mechanism within the first chamber including an actuator pin; a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; an actuator configured to release the opener mechanism to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber, and a plunger slidably disposed within the housing such that gas entering the second chamber causes the plunger to move from an initial position to an extended position wherein a distal end of the plunger extends from the housing. The plunger is coupled to a piston of an injector module and may be extendable and / or expandable axially when the pressurized gas enters the second chamber to advance the piston to deliver an agent from the injector module.

Description

DRIVE SYSTEMS FOR AUTO-INJECTORS, AUTO-INJECTOR DEVICES, AND METHODS FOR USING THEM RELATED APPLICATION DATA

[0001] The present application claims benefit of co-pending U.S. provisional application Serial No. 63 / 559,141, filed February 28, 2024, the entire disclosure of which is expressly incorporated by reference herein. The present application is also related to U.S. Patent No. 11,071,824, the entire disclosure of which is 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 auto-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 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] Gas driven auto-injectors may be implemented in a couple of ways to advance a piston or stopper within an agent chamber of a syringe containing one or more agents intended to be delivered to a subject. In one configuration, gas pressure from asource may be applied directly to the piston to advance the piston to deliver the agent(s). Such a configuration may provide a relatively shorter overall device length since a plunger is not used to advance the piston; however, it may also introduce a risk that, if the pressurized gas were to breach the piston and enter the agent chamber, the gas may enter the subject’s body through the syringe’s needle, which may potentially harm the subject.

[0005] In another configuration, a plunger is provided that is coupled to the piston such that, pressurized gas from a source advances the plunger, and consequently, the piston to deliver the agent(s). This configuration avoids the risk of the subject being exposed to the pressurized gas, since the gas remains sealed within the syringe driver; however, the overall length of the device must be increased, compared to a direct system, to accommodate the length of the plunger.

[0006] Therefore, improved devices and methods for delivering agents into a patient’s body would be useful. SUMMARY

[0007] The present application relates generally to devices and methods for delivering agents into a subject’s body and, more particularly, to auto-injectors and / or gas- powered drive systems for injection devices, and to methods for making and using such devices.

[0008] In accordance with one example, a drive module is provided for delivering one or more agents into a patient’s body that includes a drive module comprising an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including a septum disposed adjacent the actuator pin; an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the septum and cause the gas within the canister to flow through the first chamber and into the second chamber; and a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing. The plunger may be coupled to a piston of an injector module comprising an injector housing coupled to the drive module carrying an agent chamber containing one or more agents. The plunger may be extendable and / or expandableaxially when pressurized gas from the canister enters the second chamber to advance the piston to deliver the one or more agents from the agent chamber.

[0009] In accordance with another example, a device is provided for delivering one or more agents into a patient’s body that includes: a) a drive module comprising an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including a septum disposed adjacent the actuator pin; an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the septum and cause the gas within the canister to flow through the first chamber and into the second chamber; and a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing; and b) an injector module comprising an injector housing coupled to the drive housing carrying an agent chamber containing one or more agents; a piston slidably disposed within the agent chamber and coupled to the distal end of the plunger; and a needle extending from the injector module opposite the drive housing and communicating with the agent chamber for delivering the one or more agents from the agent chamber when the plunger moves from the retracted position to the extended position, thereby advancing the piston within the agent chamber.

[0010] The plunger may be extendable and / or expandable axially when pressurized gas from the canister enters the second chamber to advance the piston to deliver the one or more agents. For example, the plunger may include a plurality of telescoping elements that extend distally from a retracted position when pressurized gas from the canister enters the second chamber to an extended position, thereby directing the piston distally. A proximal end of a first plunger element may be substantially fixed relative to the second chamber and one or more additional plunger elements may be extendable axially from the first plunger element with a distal-most plunger element coupled to the piston. When pressurized gas enters the second chamber, the gas may enter interior chambers of the plunger elements to cause the plunger elements to displace distally to advance the piston.

[0011] Alternatively, the plunger may include a flexible bladder or bellows that is expandable from an initial retracted position to an extended position to advance the piston. For example, the bladder or bellows may be provided in an initial nested or other collapsedconfiguration and, as pressurized gas enters the second chamber, the gas may enter an interior of the bladder or bellows, thereby causing the bladder or bellows to expand distally. A distal end of the bladder or bellows may include a feature that is coupled to the piston and moves distally as the bladder or bellows expands to advance the piston distally.

[0012] The device may include any of the actuators disclosed in the patents incorporated by reference herein. For example, an actuation sleeve may be provided that is retracted when the needle is inserted into a patient’s skin, thereby actuating the opener mechanism to release the gas. Alternatively, a screw, lever, button, or other actuator may be provided on the drive module that may be manually activated by a user to actuate the opener mechanism to release the gas.

[0013]

[0014] 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

[0015] 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:

[0016] FIG. 1 is a perspective view of an exemplary auto-injector device including a front and rear housing, and a safety cap.

[0017] FIGS. 2A and 2B are longitudinal cross-sections of the device of FIG. 1 taken along plane 2A-2A, showing internal components of the device including a syringe carrying one or more agents including an axially expandable plunger including telescoping rods or sections in an initial retracted position and a final extended position, respectively.

[0018] FIGS. 2C and 2D are details of the device of FIGS. 2A and 2B, respectively.

[0019] FIGS. 3A and 3B are longitudinal cross-sections of the device of FIG. 1 taken along plane 2A-2A, showing internal components of the device including a syringe carrying one or more agents including another axially expandable plunger formed from a flexible bladder in an initial retracted position and a final extended position, respectively.

[0020] FIGS. 3C and 3D are details of the device of FIGS. 3A and 3B, respectively.

[0021] FIGS. 4A and 4B are longitudinal cross-sections of the device of FIG. 1 taken along plane 2A-2A, showing internal components of the device including a syringecarrying one or more agents including yet another axially expandable plunger formed from a bellows structure bladder in an initial retracted position and a final extended position, respectively.

[0022] FIGS. 4C and 4D are details of the device of FIGS. 4A and 4B, respectively.

[0023] 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 the invention; it being understood, however, that this invention is not limited to the precise arrangements shown. DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 a specifically 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.

[0029] 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.

[0030] 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 forward 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.

[0031] With additional 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 adistal 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 opener 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, which may be adjacent to or partially receive the plunger 50.

[0032] 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 opener 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. Optionally, 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.

[0033] For example, a spacer 30 may be provided that extends between the activation cap 80 and a release cap 34 of the opener 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 carriage 64 of the opener mechanism 60, as described further elsewhere herein. Optionally, the spacer 30 may be biased distally, e.g., by a spring or other biasing mechanism (not shown), which may, in turn, bias the activation cap 80 distally after completing the injection, also as described further elsewhere herein.

[0034] 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 forward 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, at least a portion of the outer surface may have a generally cylindrical shape optionally includingone 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 (not shown) for locking and / or releasing components of the opener mechanism 60, as described further elsewhere herein.

[0035] 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 forward housing 10.

[0036] For example, during manufacturing, the forward 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 forward housing 10, e.g., during manufacturing or during assembly of the device 6 any time before performing an injection. Optionally, 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 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 in FIGS. 2A and 2B, the proximal end of the safety cap 86 may include one or more fingers 86a that fall into one or more corresponding cutouts, recesses, or other features on the needle shield 79 when the syringe 70 is inserted into the forward housing 10, thereby coupling the needle shield 79 to the safety cap 86, as described elsewhere herein.

[0037] 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 opener mechanism 60 (and any other incidental components), and the rear housing 12 may be coupled to the forward housing 10 at any time. For example, during manufacturing, a syringe 70 may be loaded into the interior of the forward housing 10, and the assembled rear housing 12 may be immediately coupled to the forward housing 10. When the rear housing 12 is attached to the forward housing 10, a distal end 54 of the plunger 50 may be coupled to the piston 74within the syringe 70, e.g., such that distal movement of the plunger 50 is translated to the piston 74, as described further elsewhere herein.

[0038] 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.

[0039] The proximal end 10a of the forward 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.

[0040] 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.

[0041] Optionally, the outer housing 8 may include a mount (not shown), 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 to secure the syringe 70 relative to the forward housing 10. In addition or alternatively, one or more detents, ridges, or other features (not shown) may be provided on the forward housing 10 for securing the syringe 70. Optionally, the forward housing 10 may include one or more windows 10c in the sidewall, e.g., as shown in FIG. 1, which mayfacilitate observing the syringe 70 during an injection, e.g., to allow visual confirmation when the piston 74 is fully advanced.

[0042] 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 inner housing 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.

[0043] 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.

[0044] 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 of the opener mechanism 60 is slidably mounted, as described further elsewhere herein.

[0045] 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 argon, 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 theforces to operate the device 6, e.g., to inject one or more agents from the syringe 70 into a subject’s body.

[0046] 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.

[0047] 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 a septum or other weakened region (not shown) that may be opened by the opener 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.

[0048] 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.

[0049] 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 pressureimparted to the plunger 50, providing a limiting effect to the flow rate of the drug injected into the patient.

[0050] With continued reference to FIGS. 2A and 2B, the opener 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 the cap 44 (and septum or outlet). 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.

[0051] For example, the rear housing 12 and the carriage 64 may include cooperating locking features that prevent the carriage 64 from moving until the device 6 is activated. For example, the carriage 64 may include locking tabs or other features (not shown) on its proximal end that engage the rear housing 12 until released. 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 engaging between the carriage 64 and the proximal end of the rear housing 12.

[0052] The release cap 34 and carriage 64 include cooperating features that release the locking features from the rear housing 12 when the device 6 is activated. For example, the release cap 34 may include 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. Optionally, the release cap 34 may also include an enclosed proximal end and a distal end 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 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.

[0053] In one example, a central hub 36 is provided on a 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 biasedto move radially inwardly (towards the central axis 18), thereby directing the locking features inwardly. Once the locking features clear the proximal end 13a of the rear housing 12, e.g., the spring 66 may automatically direct the carriage 64 distally, thereby directing the opener pin 62 distally to penetrate the septum (or otherwise open the outlet) in the cap 44 of the canister 40 (or otherwise opening the outlet). Exemplary locking features that may be included in the device 6 are disclosed in U.S. Publication No. 2024 / 0033434, the entire disclosure of which is expressly incorporated by reference herein.

[0054] With additional reference to FIGS. 2C and 2D, the plunger 50 coupled to the piston 74 includes a plurality of elongate rods or other sections 52, e.g., a first or proximal rod 52a, a second or intermediate rod 52b, and a third or distal rod 52c. The rods 52 are telescopingly coupled to one another, e.g., such that the rods 52 are nested together in an initial, retracted position, e.g., as shown in FIG. 2C, and, when pressurized gas from the canister 40 enters the second chamber24, at least some of the rods 52 move distally to an extended position, e.g., as shown in FIG.2D, thereby directing the piston 74 distally to deliver the agent(s) within the agent chamber 73 of the syringe 70.

[0055] In addition, each rod 52 includes an inner chamber 58 that extends from an open proximal end of the respective rod 52 to its distal end 56 and communicate with each successive inner chamber within the rods 52. For example, as shown, each rod 52 includes a proximal end 54 and a distal end 56, e.g., with the proximal end 54a of the first rod 52 including a flange received within the distal cylinder 20b of the inner housing 20 such that the inner chamber 58a of the first rod 54a communicates with the second chamber 24 of the inner housing 20. The inner chamber 58a, 58b of the first and second rods 52a, 52b may be open at both the proximal ends 54a, 54b and distal ends 56a, 56b, while the third rod 52c may be open at its proximal end54c and closed at its distal end 56c.

[0056] The proximal end 54b of the second rod 52b is slidably received within the inner chamber 58a of the first rod 52a, e.g., initially adjacent the proximal end 54a of the first rod 52a, e.g., as shown in FIG. 2C, such that the second rod 52b may slide distally until its proximal end 54b is disposed adjacent the distal end 56a of the first rod 52a, e.g., as shown in FIG. 2D. Similarly, the proximal end 54c of the third rod 52c is slidable received within the inner chamber 58b of the second rod 52b, initially adjacent the proximal end 54b of the second rod 52b, such that the third rod 52c may slide distally until its proximal end 54c is disposed adjacent the distal end 56b of the second rod 52b.

[0057] As shown, the rods 52 may include cooperating features, e.g., outward extending flanges on their proximal ends 54 and inward extending flanges on their distal ends 56 that limit distal movement of the rods relative to one another. Optionally, the rods 52 may also include one or more seals, e.g., O-rings 59, between the rods 52 that seal the inner chambers 58 to prevent pressurized gas from leaking between the rods 52. For example, as shown, an O-ring 58a-58c may be provided around the proximal end 54a-54c of each rod 52a-52c. The first O-ring 58a may provide a seal between the proximal end 54a of the first rod 52a and a distal end of the distal cylinder 20b of the inner housing 20. The second and third O-rings 58b, 58c may provide a seal between the first and second rods 52a, 52b and the second and third rods 52b, 52c, respectively, while sliding along the inner wall of the second and third rods 52b, 52c to accommodate distal movement.

[0058] Optionally, as shown, the distal end 20c of the distal cylinder 20b may include an inward extending flange that cooperates with an outward extending flange on the proximal end 54a of the first rod 52a to prevent distal movement of the first rod 52a. Initially, the first rod 52a may be provided with its proximal end 52a abutting the distal end 20c of the distal cylinder 20b, e.g., as shown in FIG. 2C, such that the first rod 52a does not move during activation of the device 6. Alternatively, the first rod 52a may be provided within the distal cylinder 20b with the proximal end 54a proximal to the distal end 20c such that the first rod 52a also moves distally during activation of the device 6 (limited by the flanges on the proximal end 54a and distal end 20c). In a further alternative, the first rod may be permanently attached to the distal cylinder 20b.

[0059] Consequently, when pressurized gas enters the second chamber 24 (via the first chamber 22 from the gas cylinder 60), the pressurized gas enters the inner chambers 58a, 58b, 58c of the rods 52a-52 (limited by the closed distal end 56c of the third rod 52c), thereby generating a distal force to direct the rods 52 distally from the initial position (shown in FIG. 2C) towards the extended position (shown in FIG. 2D) 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.

[0060] 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. For example, the safety cap 86 may include inner and outer cylindricalmembers with the proximal end of the inner cylindrical member coupled to the needle shield 79 and a proximal end of the outer cylindrical 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.

[0061] 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.

[0062] Once exposed, 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 an initial, distal position, e.g., as shown in FIGS. 2A and 2B, to a retracted position (not shown) as the needle 78 enters the subject’s skin. This action may activate the opener 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 has may advance the plunger 50 and, consequently, the piston 74 to deliver the agent(s) through the needle 78 into the subject.

[0063] For example, initially, the proximal end 82 of the activation cap 80 may abut or otherwise engage a distal end 30b of the spacer 30, and a proximal end 30a of the spacer 30 may abut or otherwise engage a distal end of the release cap 34. Consequently, when the activation cap 80 is retracted proximally within the outer housing 8, the activation cap 80 pushes the spacer 30 proximally, and, in turn, the spacer 30 pushes the release cap 34 proximally, e.g., until the proximal end of the release cap 34 contacts the proximal end 8c of the outer housing 8.

[0064] 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. Optionally, as the spacer 30 is directed proximally, a spacer spring (not shown, see, e.g., spacer spring 132 shown in FIGS. 3A and 3B) may be compressed, e.g., between features on the spacer 30 and the inner housing 20, thereby biasing the spacer 30subsequently 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.

[0065] Since the carriage 64 is secured relative to the inner housing 20 by locking features, the carriage 64 also remains substantially stationary, such that the release cap 34 moves proximally relative to the carriage 64, e.g., such that the tabs 65 on the carriage 64 slide along the hub 36 on the release cap 34. When the release cap 34 reaches its proximal- most position, 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 on the carriage 64, the inward movement of the tabs 65 causes the locking features to move inwardly, thereby disengaging the locking features and releasing the carriage 64.

[0066] 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. Optionally, the release cap 34 may include one or more tabs or other features (not shown) corresponding to pockets or other features (also not shown) in the outer housing 8, such that, when the release cap 34 reaches its proximal-most position, the tabs are received in respective pocket to prevent the release cap 34 from moving distally as the carriage 64 advances distally due to the spring 66.

[0067] 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.

[0068] The pressurized gas within the second chamber 24 enters the inner chambers 58a-58c of the rods 52a-52c to generate a distal force to direct the second and third rods 52b, 52c, distally, thereby advancing the piston 74 to deliver the one or more agents from the syringe 70 through the needle 78 into the subject.

[0069] The operator may monitor the syringe 70 during the injection, e.g., via the window(s) 8c shown in FIG. 1, 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 spacer 30, thespacer 30 may automatically advance distally, thereby directing the activation cap 80 distally to cover the needle 78 as it is withdrawn.

[0070] 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 forward housing 10, and the syringe 70 may be removed.

[0071] One of the advantages of the telescoping rods 52 of the plunger 50 is that they may allow an overall length of the device 6 to be shortened, e.g., relative to a single piece, fixed axial length plunger, such as those disclosed in the patents identified elsewhere herein.

[0072] For example, as shown in FIG. 2C, the device 6 is shown with a region “L” between the canister 40 and / or transition between the first and second chambers 22, 24, and the distal end 20c of the inner housing 20. If a single, piece plunger were provided instead of the plunger 50, this region “L” would be required to provide a plunger that has a length that is sufficiently long to be positioned within the second chamber 24 yet be coupled to the piston 74, and advance the piston 74 sufficiently to deliver the agent(s) within the agent chamber 73.

[0073] In contrast, with the plunger 50 shown in FIGS. 2A and 2B, in the initial position, the overall length P1 of the retracted plunger 50 shown in FIG.2A is substantially shorter due to the nesting of the rods 52, as compared with the overall length P2 of the extended plunger 50 shown in FIG. 2B (which may correspond to the required length of a fixed length plunger). Thus, the device 6 may have its overall length shortened by as much as the difference between the overall lengths P2-P1, e.g., as compared to a fixed length plunger that would need to have a length comparable to P2 to completely advance the piston 74.

[0074] Further, in addition to reducing the overall length of the device 6, the plunger 50 may allow a smaller volume second chamber 24 to be provided within the inner housing 20 compared to a fixed length plunger. Thus, a smaller volume of pressurized gas may be provided within the canister 40, if desired, while providing sufficient pressure to advance the rods 52 of the plunger 50.

[0075] Turning to FIGS. 3A-3D, another example of an auto-injector device 106 is shown that includes components generally similar to the device 6 (e.g., with ref. nos. of like items increased by 100 other than the syringe 70 and gas canister 40, which are generallythe same), e.g., including an outer housing 108 including a front housing 110 carrying a syringe 70 containing one or more agents within an agent chamber, and a rear housing 112 including a drive assembly for automatically delivering the agent(s) from the syringe 70 when the device 106 is activated. As shown, the device 106 also includes a safety cap 186 provided on the front housing 110, e.g., covering an activation cap 180, which is operatively coupled to a spacer 130, which is, in turn, operatively coupled to an opener mechanism 160, e.g., including a release cap 134 and carriage 164 configured to open a gas canister 40 to release pressurized gas, when the device 106 is activated, e.g., generally similar to the device 6.

[0076] As shown in FIGS. 3A and 3B, the device 106 includes an inner housing 120 mounted within the outer housing 108 that includes a first or proximal chamber 122, e.g., within which the gas canister 40 is mounted, and a second or distal chamber 124, which may be adjacent to or partially receive a plunger 150.

[0077] In the example shown, the inner housing 120 includes a proximal cylinder 120a including the first chamber 122 and a distal cylinder 120b including the second chamber 124. The proximal and distal cylinders 120a, 120b may be permanently attached together to provide the inner housing 120, 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, or may be formed as a single, unitary structure, similar to the inner housing 20.

[0078] Optionally, the distal cylinder 120b may have a length such that a distal end 120c of the distal cylinder 120b may abut the syringe 70 when the device 106 is assembled (e.g., as shown in FIGS. 3A and 3B). Optionally, the distal end 120c may include one or more features that contact the proximal end of the syringe 70, e.g., an O-ring (not shown) secured on or around the distal end formed from resilient and / or relatively flexible material, which may prevent the distal end from damaging the syringe 70, e.g., if the barrel 72 is made from glass.

[0079] With additional reference to FIGS. 3C and 3D, the plunger 150 includes an axially expandable bladder or other flexible tubular body 152, which includes a first or proximal end 154 coupled to the distal end 120c of the distal cylinder 120b of the inner housing 120, a second or distal end 156 coupled to a pin or stud 157, and an inner chamber or passage 158 extending between the ends 154, 156. For example, the first end 154 of the bladder 152 and the distal end 120c of the distal cylinder 120b may be permanently attached to one another, e.g., by one or more of cooperating connectors, bonding with adhesive,sonic welding, fusing, and the like, such that the inner chamber 158 communicates with the second chamber 124 through the first end 154. Optionally, one or more seals, e.g., an O- ring (not shown), may be provided between the first end 154 of the bladder 152 and the distal end 120c of the distal cylinder 120b, if desired to provide a fluid-tight seal.

[0080] The second end 156 of the bladder 152 may be permanently attached around or otherwise to the stud 157, e.g., by one or more of cooperating connectors, bonding with adhesive, sonic welding, fusing, and the like, thereby closing the inner chamber 158 at the second end 156. The stud 157 may be configured to be coupled to the piston 74 of the syringe, e.g., by one or more mating threads or other connectors, or simply by the stud 157 being received within a recess in the piston 74 (not shown). Alternatively, the stud 157 may be integrally formed with the bladder 152, e.g., to close the distal end 156 and provide a feature for coupling to the piston 74 of the syringe 70.

[0081] The bladder 152 may be formed from flexible material such that the bladder 152 may be folded or otherwise axially compressed such that the second end 156 is initially provided close to the first end 154 in a retracted position, e.g., as best seen in FIG. 3C. For example, the bladder 152 may have an overall length P4 in the extended position, e.g., as shown in FIG. 3D, with the first and second ends 154, 156 spaced axially apart from one another. The bladder 152 may be folded concentrically around itself one or more times, e.g., two, three, four, or more times, as desired, to reduce the overall length of the bladder 152 in the initial position to an overall length P3, such as that shown in FIG. 3C.

[0082] In the retracted position, the inner chamber 158 remains exposed to the second chamber 124 such that, when pressurized gas enters the second chamber 124, the gas enters the inner chamber 158 as represented by P in FIG. 3D), thereby applying a distal force to the closed second end 156. This distal force directs the second end 156 and stud 157 distally away from the first end 154 to cause the bladder 152 to unfold until it is fully expanded distally, thereby directing the piston 74 distally to deliver the agent(s) within the agent chamber 73.

[0083] The bladder 152 may be formed from flexible, inelastic materials, e.g., polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and the like, that may be easily folded concentrically and unfold when exposed to pressurized gas. The inelastic material may prevent the wall of the bladder 152 from expanding or otherwise deforming substantially, such that the internal pressure P fromthe pressurized gas acts primarily on the closed second end 156 to direct the stud 157 and, consequently, the piston 74 distally.

[0084] Given the concentric folding of the bladder 152 in the retracted position, the device 106 an overall length of the device 6 to be shortened, e.g., relative to a single piece, fixed axial length plunger such as those disclosed in the references identified herein, similar to the plunger 50 of the device 6. For example, as shown in FIG. 3C, the device 106 is shown with a region “L” between the canister 40 and / or transition between the first and second chambers 122, 124, and the distal end 120c of the inner housing 120. If a single, piece plunger were provided instead of the plunger 150, this region “L” would be required to provide a plunger that has a length that is sufficiently long to be positioned within the second chamber 124 yet be coupled to the piston 74, and advance the piston 74 sufficiently to deliver the agent(s) within the agent chamber 73. Thus, providing the bladder 152 for the plunger 150 may allow much or all of this region “L” to be removed from the device 106 to provide a more compact injector device.

[0085] Turning to FIGS. 4A-4D, another example of an auto-injector device 206 is shown that includes components generally similar to the device 106 (e.g., with ref. nos. of like items increased by 100 other than the syringe 70 and gas canister 40), e.g., including an outer housing 208 including a front housing 210 carrying a syringe 70 containing one or more agents within an agent chamber, and a rear housing 212 including a drive assembly for automatically delivering the agent(s) from the syringe 70 when the device 206 is activated. As shown, the device 206 also includes a safety cap 286 provided on the front housing 210, e.g., covering an activation cap 280, which is operatively coupled to a spacer 230, which is, in turn operatively coupled to an opener mechanism 260, e.g., including a release cap 234 and carriage 264 configured to open a gas canister 40 to release pressurized gas, when the device 206 is activated.

[0086] As shown, the device 206 includes an inner housing 220 mounted within the outer housing 208 that includes a first or proximal chamber 222, e.g., within which the gas canister 40 is mounted, and a second or distal chamber 224.

[0087] In the example shown, the inner housing 220 includes a proximal cylinder 220a including the first chamber 222 and a distal cylinder 220b including the second chamber 224. The proximal and distal cylinders 220a, 220b may be permanently attached together to provide the inner housing 220, 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, or may be formed as a single, unitary structure, similar to the inner housing 20. Optionally, the distal cylinder 220b may have a length such that a distal end 220c of the distal cylinder 220b may abut the syringe 70 when the device 206 is assembled (not shown), e.g., similar to the other devices herein.

[0088] With additional reference to FIGS. 4C and 4D, the plunger 250 includes an axially expandable tubular body 252, which includes a first or proximal end 254 coupled to the distal end 220c of the distal cylinder 220b of the inner housing 220, a second or distal end 256, and an inner chamber or passage 258 extending between the ends 254, 256. For example, the first end 254 of the tubular member 252 and the distal end 220c of the distal cylinder 220b may be permanently attached to one another, e.g., by one or more of cooperating connectors, bonding with adhesive, sonic welding, fusing, and the like, such that the inner chamber 258 communicates with the second chamber 224 through the first end 254. Optionally, one or more seals, e.g., an O-ring (not shown), may be provided between the first end 254 of the bladder 252 and the distal end 220c of the distal cylinder 220b, if desired to provide a fluid-tight seal.

[0089] In this example, the tubular body 252 includes a plurality of axially spaced pleats or folds that provide a bellows structure, i.e., such that the tubular body 252 may be compressed axially to dispose the second end 256 relatively close to the first end 254 in the retracted position, e.g., as shown in FIG. 4A. The second end 256 is closed and may include a pin or stud 257, which may be attached to or integrally formed in the second end 256 to close the inner chamber 258 and to allow the second end 256 to be coupled to the piston 74 of the syringe 70, similar to the other devices herein.

[0090] The tubular body 252 may be formed from flexible, inelastic materials, e.g., polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and the like, that may be easily folded along its length to form the bellows shape and unfold when exposed to pressurized gas. The inelastic material may prevent the wall of the bladder 252 from expanding or otherwise deforming substantially, such that the internal pressure P from the pressurized gas acts primarily on the closed second end 256 to direct the stud 257 and, consequently, the piston 74 distally, while accommodating the axial compression and extension of the plunger 250 during use of the device 206.

[0091] The device 206 may be used in a similar manner to the devices 6, 106 to deliver one or more agents within the agent chamber 73 of the syringe 70. For example,after removing the safety cap 286, the contact surface 284 may be placed against a subject’s skin (not shown) and then the device 206 may be pressed against the skin to insert the needle 78, thereby causing the activation cap 280 to slide proximally from its initial, distal position to a retracted position as the needle 78 enters the subject’s skin. Consequently, when the activation cap 280 is retracted proximally within the outer housing 208, the activation cap 280 pushes the spacer 230 proximally, and, in turn, the spacer 230 pushes the release cap 234 proximally, e.g., until the carriage 264 is released. Due to its distal bias, the carriage directs the opener pin 262 distally to open the outlet of the canister 40, thereby releasing the pressurized gas within the canister 40.

[0092] The released pressurized gas then enters the first chamber 222, e.g., around the canister 40, and passes to the second chamber 224, thereby pressurizing the second chamber 224 and entering the inner chamber 258 of the plunger 250 to generate a distal force to direct the second end 256 and stud 257 distally, thereby advancing the piston 74 to deliver the one or more agents from the syringe 70 through the needle 78 into the subject. The pleats or folds of the bellows structure of the tubular body 252 may open axially to accommodate distal expansion of the plunger 250 to direct the second end 256 distally.

[0093] Once the injection is completed, the device 206 may be directed away from the subject, thereby withdrawing the needle 78 from the subject’s skin. As the device 206 is directed away from the subject’s skin, the activation cap 280 may automatically move distally thereby directing the activation cap 280 distally to cover the needle 78 as it is withdrawn. The device 206 may then be discarded or at least partially cleaned and reused, similar to the other devices herein.

[0094] 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 patient’s body, comprising: a) a drive module comprising: i) an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; ii) a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; iii) an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and iv) a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing; and b) an injector module comprising: i) an injector housing coupled to the drive housing carrying an agent chamber containing one or more agents; ii) a piston slidably disposed within the agent chamber and coupled to the distal end of the plunger; and iii) a needle extending from the injector module opposite the drive housing and communicating with the agent chamber for delivering the one or more agents from the agent chamber when the plunger moves from the retracted position to the extended position, thereby advancing the piston within the agent chamber, wherein the plunger is extendable and / or expandable axially when pressurized gas from the canister enters the second chamber to advance the piston to deliver the one or more agents.

2. The device of claim 1, wherein the plunger comprises a plurality of telescoping elements that are nested together in the initial retracted position and, when pressurized gas from the canister enters the second chamber, the telescoping elements areconfigured to expand distally to the extended position, thereby directing the second end of the plunger and, consequently, the piston distally.

3. The device of claim 2, wherein a proximal end of a first plunger element of the telescoping elements is substantially fixed relative to the second chamber and one or more additional plunger elements of the telescoping elements are extendable axially from the first plunger element with a distal-most plunger element comprising the second end coupled to the piston.

4. The device of claim 3, wherein, when pressurized gas enters the second chamber, the gas enters interiors of the plunger elements to cause the plunger elements to displace distally to advance the piston.

5. The device of claim 1, wherein the plunger comprises a flexible bladder that is expandable from the initial retracted position to the extended position to advance the piston.

6. The device of claim 5, wherein the bladder is provided in a nested or other collapsed configuration in the initial retracted position and, as pressurized gas enters the second chamber, the pressurized gas enters an interior of the bladder, thereby causing the bladder to expand distally to the extended position.

7. The device of claim 6, wherein a distal end of the bladder includes a feature that is coupled to the piston and moves distally as the bladder expands to advance the piston distally.

8. The device of claim 6, wherein the bladder is folded concentrically around itself in the nested or otherwise collapsed configuration and wherein the bladder is configured to unfold as the bladder expands distally to the extended position.

9. The device of claim 8, wherein the bladder is folded such that a wall of the bladder overlaps itself multiple times between proximal and distal ends of the bladder in the initial nested configuration, and wherein the wall extends axially between proximal anddistal ends of the bladder in an extended position when the pressurized has is received in the interior of the bladder.

10. The device of claim 1, wherein the plunger comprises a bellows that is expandable from the initial retracted position to the extended position to advance the piston.

11. The device of claim 10, wherein the bellows comprises a proximal end substantially fixed relative to the second chamber, a distal end coupled to the piston, and a plurality of pleats between the proximal and distal ends, the pleats configured to expand when pressurized gas enters the second chamber and enters an interior of the bellows, thereby causing the bellows to expand distally to advance the piston distally.

12. The device of claim 11, wherein the pleats are configured to open distally as the plunger expands from the initial retracted position to the extended position. 13.device for delivering one or more agents into a patient’s body, comprising: a) a drive module comprising: i) an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; ii) a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; iii) an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and iv) a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing; and b) an injector module comprising: i) an injector housing coupled to the drive housing carrying an agent chamber containing one or more agents;ii) a piston slidably disposed within the agent chamber and coupled to the distal end of the plunger; and iii) a needle extending from the injector module opposite the drive housing and communicating with the agent chamber for delivering the one or more agents from the agent chamber when the plunger moves from the retracted position to the extended position, thereby advancing the piston within the agent chamber, wherein the plunger comprises a plurality of telescoping elements that are nested together in the initial retracted position and, when pressurized gas from the canister enters the second chamber, the telescoping elements are configured to expand distally to the extended position, thereby directing the second end of the plunger and, consequently, the piston distally.

14. The device of claim 13, wherein a proximal end of a first plunger element of the telescoping elements is substantially fixed relative to the second chamber and one or more additional plunger elements of the telescoping elements are extendable axially from the first plunger element with a distal-most plunger element comprising the second end coupled to the piston.

15. The device of claim 14, wherein, when pressurized gas enters the second chamber, the gas enters interiors of the plunger elements to cause the plunger elements to displace distally to advance the piston.

16. A device for delivering one or more agents into a patient’s body, comprising: a) a drive module comprising: i) an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; ii) a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; iii) an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; andiv) a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing; and b) an injector module comprising: i) an injector housing coupled to the drive housing carrying an agent chamber containing one or more agents; ii) a piston slidably disposed within the agent chamber and coupled to the distal end of the plunger; and iii) a needle extending from the injector module opposite the drive housing and communicating with the agent chamber for delivering the one or more agents from the agent chamber when the plunger moves from the retracted position to the extended position, thereby advancing the piston within the agent chamber, wherein the plunger comprises a flexible bladder that is provided in a nested or other collapsed configuration in the initial retracted position where the bladder is folded concentrically around itself in the nested or otherwise collapsed configuration and wherein the bladder is configured to unfold as the pressurized gas enters an interior of the bladder, thereby causing the bladder to expand distally to the extended position.

17. The device of claim 16, wherein a distal end of the bladder includes a feature that is coupled to the piston and moves distally as the bladder expands to advance the piston distally.

18. The device of claim 16, wherein the bladder is folded such that a wall of the bladder overlaps itself multiple times between proximal and distal ends of the bladder in the initial nested configuration, and wherein the wall extends axially between proximal and distal ends of the bladder in an extended position when the pressurized has is received in the interior of the bladder.

19. A device for delivering one or more agents into a patient’s body, comprising: a) a drive module comprising: i) an elongate drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the secondend; an opener mechanism within the first chamber adjacent the first end including an actuator pin; ii) a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; iii) an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and iv) a plunger slidably disposed within the second chamber such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing; and b) an injector module comprising: i) an injector housing coupled to the drive housing carrying an agent chamber containing one or more agents; ii) a piston slidably disposed within the agent chamber and coupled to the distal end of the plunger; and iii) a needle extending from the injector module opposite the drive housing and communicating with the agent chamber for delivering the one or more agents from the agent chamber when the plunger moves from the retracted position to the extended position, thereby advancing the piston within the agent chamber, wherein the plunger comprises a bellows including a proximal end substantially fixed relative to the second chamber, a distal end coupled to the piston, and a plurality of pleats between the proximal and distal ends, the pleats configured to expand when pressurized gas enters the second chamber and enters an interior of the bellows, thereby causing the bellows to expand distally to advance the piston distally.

20. The device of claim 19, wherein the pleats are configured to open distally as the plunger expands from the initial retracted position to the extended position.

21. The device of any one of claims 1-20, wherein the actuator comprises an actuator sleeve that is retracted when the injector housing is pressed against a patient’s skin to insert the needle, the actuator sleeve configured to release the opener mechanism to cause the actuator pin to open the outlet and release the pressurized gas.

22. The device of claim 21, wherein the opener mechanism comprises a release cap that is operatively coupled to the actuator sleeve such that the release cap is directed proximally when the actuator sleeve is retracted, and a carriage carrying the actuator pin that is released when the release cap is directed proximally, whereupon the carriage is configured to move axially to direct the actuator pin thereon to open the outlet.

23. The device of claim 22, wherein the opener mechanism further comprises a carriage within the first chamber carrying the actuator pin located adjacent the outlet and releasably coupled to the release cap, the release cap and carriage comprising one or more features that disengage when the release cap is directed proximally by the actuator sleeve, the carriage biased to move axially when released to move the actuator pin, thereby causing the actuator pin to open the outlet to release the pressurized gas into the first chamber and into the second chamber such that the pressurized gas advances the plunger.

24. The device of claim 23, further comprising: an activation cap on the distal end of the injector housing initially covering the needle; a spacer surrounding one or both of the drive housing and the injector housing proximal to the activation cap; the activation cap movable axially relative to the injector housing such that, when a contact surface of the activation cap is pressed against a subject’s skin to insert the needle, the activation cap is configured to move proximally to direct the spacer proximally, the spacer consequently directing the release cap proximally to release the carriage, thereby causing the carriage to move axially to open the outlet and release the pressurized gas into the first chamber and into the second chamber.

25. The device of claim 24, wherein the spacer is biased 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.

26. The device of claim 25, wherein the spacer comprises one or more locking members for preventing subsequent proximal movement of the spacer and activation cap.

27. The device of any one of claims 1-20, wherein the outlet of the gas canister is oriented proximally within the first chamber, and the actuator pin is oriented distally towards the outlet.

28. The device of claim 21, wherein the outlet of the canister comprises a septum and wherein the actuator pin is configured to at least partially tear or puncture the septum to open the outlet and release the pressurized gas.

29. The device of any one of claims 1-20, wherein the actuator comprises a manual actuator on the drive module that may be manually activated by a user to actuate the opener mechanism to open the outlet and release the pressurized gas.

30. The device of claim 29, wherein the manual actuator comprises one of a screw, a button, and a lever.

31. A drive module for delivering one or more agents into a patient’s body from an injector module comprising an agent chamber containing one or more agents, an outlet, and a piston, comprising: a drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and a plunger slidably disposed within the drive housing such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing, the plunger extendable and / or expandable axially when pressurized gas from thecanister enters the second chamber to advance the piston of the injector module to deliver the one or more agents from the agent chamber through the outlet.

32. The drive module of claim 31, wherein the plunger comprises a plurality of telescoping elements that are nested together in the initial retracted position and, when pressurized gas from the canister enters the second chamber, the telescoping elements are configured to expand distally to the extended position, thereby directing the second end of the plunger and, consequently, the piston distally.

33. The drive module of claim 32, wherein a proximal end of a first plunger element of the telescoping elements is substantially fixed relative to the second chamber and one or more additional plunger elements of the telescoping elements are extendable axially from the first plunger element with a distal-most plunger element comprising the second end coupled to the piston.

34. The drive module of claim 33, wherein, when pressurized gas enters the second chamber, the gas enters interiors of the plunger elements to cause the plunger elements to displace distally to advance the piston.

35. The drive module of claim 31, wherein the plunger comprises a flexible bladder that is expandable from the initial retracted position to the extended position to advance the piston.

36. The drive module of claim 35, wherein the bladder is provided in a nested or otherwise collapsed configuration in the initial retracted position and, as pressurized gas enters the second chamber, the pressurized gas enters an interior of the bladder, thereby causing the bladder to expand distally to the extended position.

37. The drive module of claim 36, wherein a distal end of the bladder includes a feature that is coupled to the piston and moves distally as the bladder expands to advance the piston distally.

38. The drive module of claim 36, wherein the bladder is folded concentrically around itself in the nested or otherwise collapsed configuration and wherein the bladder is configured to unfold as the bladder expands distally to the extended position.

39. The drive module of claim 38, wherein the bladder is folded such that a wall of the bladder overlaps itself multiple times between proximal and distal ends of the bladder in the initial nested configuration, and wherein the wall extends axially between proximal and distal ends of the bladder in an extended position when the pressurized has is received in the interior of the bladder.

40. The drive module of claim 31, wherein the plunger comprises a bellows that is expandable from the initial retracted position to the extended position to advance the piston.

41. The drive module of claim 40, wherein the bellows comprises a proximal end substantially fixed relative to the second chamber, a distal end coupled to the piston, and a plurality of pleats between the proximal and distal ends, the pleats configured to expand when pressurized gas enters the second chamber and enters an interior of the bellows, thereby causing the bellows to expand distally to advance the piston distally.

42. The drive module of claim 41, wherein the pleats are configured to open distally as the plunger expands from the initial retracted position to the extended position.

43. A drive module for delivering one or more agents into a patient’s body from an injector module comprising an agent chamber containing one or more agents, an outlet, and a piston, comprising: a drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including an outlet disposed adjacent the actuator pin;an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and a plunger slidably disposed within the drive housing such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing, the plunger comprising a plurality of telescoping elements that are nested together in the initial retracted position and, when pressurized gas from the canister enters the second chamber, the telescoping elements are configured to expand distally to the extended position, thereby directing the second end of the plunger and, consequently, the piston distally.

44. The drive module of claim 43, wherein a proximal end of a first plunger element of the telescoping elements is substantially fixed relative to the second chamber and one or more additional plunger elements of the telescoping elements are extendable axially from the first plunger element with a distal-most plunger element comprising the second end coupled to the piston.

45. The drive module of claim 44, wherein, when pressurized gas enters the second chamber, the gas enters interiors of the plunger elements to cause the plunger elements to displace distally to advance the piston.

46. A drive module for delivering one or more agents into a patient’s body from an injector module comprising an agent chamber containing one or more agents, an outlet, and a piston, comprising: a drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; anda plunger slidably disposed within the drive housing such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drive housing, the plunger comprising a flexible bladder that is provided in a nested or other collapsed configuration in the initial retracted position where the bladder is folded concentrically around itself in the nested or otherwise collapsed configuration and wherein the bladder is configured to unfold as the pressurized gas enters an interior of the bladder, thereby causing the bladder to expand distally to the extended position.

47. The drive module of claim 46, wherein a distal end of the bladder includes a feature that is coupled to the piston and moves distally as the bladder expands to advance the piston distally.

48. The drive module of claim 46, wherein the bladder is folded such that a wall of the bladder overlaps itself multiple times between proximal and distal ends of the bladder in the initial nested configuration, and wherein the wall extends axially between proximal and distal ends of the bladder in an extended position when the pressurized has is received in the interior of the bladder.

49. A drive module for delivering one or more agents into a patient’s body from an injector module comprising an agent chamber containing one or more agents, an outlet, and a piston, comprising: a drive housing including a first end and a second end, a first chamber adjacent the first end communicating with a second chamber adjacent the second end; an opener mechanism within the first chamber adjacent the first end including an actuator pin; a canister containing pressurized gas including an outlet disposed adjacent the actuator pin; an actuator configured to move one of the opener mechanism and the canister to cause the actuator pin to open the outlet and cause the gas within the canister to flow through the first chamber and into the second chamber; and a plunger slidably disposed within the drive housing such that gas entering the second chamber causes the plunger to move from an initial retracted position to an extended position wherein a distal end of the plunger extends from the second end of the drivehousing, the plunger comprising a bellows including a proximal end substantially fixed relative to the second chamber, a distal end coupled to the piston, and a plurality of pleats between the proximal and distal ends, the pleats configured to expand when pressurized gas enters the second chamber and enters an interior of the bellows, thereby causing the bellows to expand distally to advance the piston distally.

50. The drive module of claim 49, wherein the pleats are configured to open distally as the plunger expands from the initial retracted position to the extended position.

51. The drive module of any one of claims 21-50, wherein the actuator comprises an actuator sleeve that is retracted when the injector housing is pressed against a patient’s skin to insert the needle, the actuator sleeve configured to release the opener mechanism to cause the actuator pin to open the outlet and release the pressurized gas.

52. The drive module of claim 51, wherein the opener mechanism comprises a release cap that is operatively coupled to the actuator sleeve such that the release cap is directed proximally when the actuator sleeve is retracted, and a carriage carrying the actuator pin that is released when the release cap is directed proximally, whereupon the carriage is configured to move axially to direct the actuator pin thereon to open the outlet.

53. The drive module of claim 52, wherein the outlet of the canister comprises a septum and wherein the actuator pin is configured to at least partially tear or puncture the septum to open the outlet and release the pressurized gas.

54. The drive module of any one of claims 21-50, wherein the actuator comprises a manual actuator on the drive module that may be manually activated by a user to actuate the opener mechanism to open the outlet and release the pressurized gas.

55. The drive module of claim 54, wherein the manual actuator comprises one of a screw, a button, and a lever.

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