Manual plug-in automatic injector and method of use

Abstract

The autoinjector includes a front housing carrying a syringe and an activation cap covering a needle of the syringe; and a rear housing including a drive assembly for automatically delivering the use agent (s) from the syringe when the device is activated. The rear shell includes a gas tank and an opener mechanism for opening the tank into a set of chambers of the inner shell within the outer shell. When the contact surface of the activation cap is pressed against the skin of the subject to insert the needle, the activation cap retracts into the outer housing and activates the opener mechanism to release pressurized gas from the canister into the chamber, thereby advancing the plunger in the inner housing to deliver the use agent (s) from the syringe into the subject. After the injection is completed and the device is withdrawn from the skin, the activation cap is automatically advanced to cover the needle.

Description

[0001] Relevant application materials

[0002] This application claims the benefit of co-pending U.S. Provisional Application Serial No. 63 / 394,235, filed on August 1, 2022, the entire disclosure of which is expressly incorporated herein by reference. Technical Field

[0003] The present application relates generally to devices and methods for delivering an agent into a subject, and more particularly to automatic injectors and / or pneumatic drive systems for injection devices and to methods of making and using such devices. Background Art

[0004] There are multiple applications related to the delivery of drugs or other agents into the patient's body subcutaneously, intramuscularly or otherwise. For example, the following automatic injector is available: including a predetermined dose of an agent that can be automatically delivered into the patient's body, such as after being arranged against the patient's skin and activated. In general, such automatic injectors are spring-loaded syringes that are activated to release a spring, which generates enough force to penetrate the skin with a needle and deliver the dose in the syringe. For viscous fluids, the force required to generate a fluid flow may be higher than the force that a spring-powered system can provide. When a spring can be used, it must generate a relatively large force, which requires a high-quality spring. Therefore, such automatic injectors may generate significant noise, generate pressure spikes in the syringe, cause glass breakage, vibrations and / or may drive the needle to enter the patient's skin vigorously, which may cause pain and / or may scare the user, particularly when the patient himself gives the injection.

[0005] Therefore, improved devices and methods for delivering agents to a patient would be useful. Summary of the invention

[0006] The present application relates generally to devices and methods for delivering an agent into a subject, and more particularly to automatic injectors and / or pneumatic drive systems for injection devices, and to methods of making and using such devices.

[0007] According to one example, an injector device is provided for delivering one or more agents into a subject's body, comprising a housing including a proximal portion terminating at a proximal end and a distal portion terminating at an open distal end; a syringe including a barrel containing one or more agents, a needle extending distally from the barrel such that the needle tip is disposed within the distal portion adjacent the distal end, and a piston disposed within the proximal end of the barrel; an inner housing within the housing including a first chamber adjacent the proximal end of the housing and a second chamber between the first chamber and the proximal end of the barrel; an activation cap on the distal end of the housing such that a contact surface is disposed distally of the distal end of the housing and an activation cap extension extends proximally around the barrel; a pressurized gas source within the first chamber; a release cap within the housing adjacent the proximal end of the housing carrying an opener pin positioned adjacent the pressurized gas source; a spacer within the housing adjacent to the inner housing including a distal end adjacent the proximal end of the activation cap extension and a proximal end adjacent the release cap; and a plunger including a proximal end located within the second chamber and a distal end connected to the piston of the syringe. The activation cap is axially movable relative to the housing so that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap is configured to move proximally to guide the spacer proximally, and the spacer thus guides the release cap proximally to release the opener pin, thereby causing the opener pin to open the pressurized gas source to release the pressurized gas into the first chamber and the second chamber, so that the pressurized gas propels the plunger to guide the piston distally, thereby delivering the one or more agents through the needle. In addition, the spacer can be biased to advance distally so that when the activation cap is released when the contact surface is guided away from the skin of the subject after delivery of the one or more agents, the spacer guides the activation cap distally to cover the needle, and the spacer includes one or more locking members for preventing subsequent proximal movement of the spacer and the activation cap.

[0008] According to another example, a device for delivering one or more agents into a subject is provided, the device comprising a housing including a proximal portion terminating at a proximal end and a distal portion terminating at an open distal end; a syringe including a barrel containing one or more agents, a needle extending distally from the barrel such that the tip of the needle is disposed within the distal portion adjacent the distal end, and a piston disposed within the proximal end of the barrel; an inner housing disposed within the housing including a first chamber adjacent the proximal end of the housing and a second chamber disposed between the first chamber and the proximal end of the barrel; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the distal end of the housing; a source of pressurized gas within the first chamber; a release cap disposed within the housing adjacent the proximal end of the housing, carrying an opener pin positioned adjacent the source of pressurized gas, the release cap being operably connected to the activation cap such that proximal movement of the activation cap can guide the release cap proximally; and a plunger including a proximal end disposed within the second chamber and a distal end coupled to the piston of the syringe. The activation cap is axially movable relative to the housing such that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap is configured to retract proximally into the distal end to guide the release cap proximally to release the opener pin, thereby causing the opener pin to open a pressurized gas source to release the pressurized gas into the first chamber and the second chamber, causing the pressurized gas to advance the plunger to guide the piston distally to deliver one or more agents through the needle.

[0009] According to yet another example, a method for delivering one or more agents into a subject is provided, the method comprising providing an injector device comprising a housing carrying a syringe comprising a barrel containing one or more agents and a needle extending distally from the barrel such that the tip of the needle is disposed adjacent an activation cap on the distal end of the housing; an inner housing within the housing comprising a first chamber and a second chamber; and a source of pressurized gas within the proximal chamber; pressing a contact surface of the activation cap against the subject's skin to insert the needle into the skin, thereby retracting the activation cap proximally into the housing to cause a carrier carrying an opener pin to be released and advanced to open an outlet of the pressurized gas source into the first chamber and the second chamber, the pressure of the pressurized gas advancing a plunger within the housing to deliver the one or more agents from the barrel through the needle into the subject; and withdrawing the needle from the subject's skin, the activation cap automatically advancing to cover the needle.

[0010] According to yet another example, a method for assembling an injector device is provided, comprising providing a front shell comprising a proximal end and a distal end and an activation cap located on the distal end such that a contact surface is disposed distal to the distal end; providing a rear shell comprising a proximal end and a distal end and an interior extending therebetween, the rear shell comprising a release cap adjacent to the proximal end of the rear shell in the interior, the release cap carrying an opener pin positioned adjacent to a source of pressurized gas, and an inner shell within the interior comprising a first chamber and a second chamber and a plunger, the plunger comprising a proximal end within the second chamber; loading a syringe into the interior of the front shell such that a needle of the syringe is located within the front shell and proximal to the contact surface; and coupling the distal end of the rear shell to the proximal end of the front shell, thereby coupling the plunger to a piston within the syringe. The activation cap can be axially movable relative to the front shell so that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap moves proximally to guide the release cap proximally to release the opener pin, thereby causing the opener pin to open the pressurized gas source to release the pressurized gas into the first chamber and the second chamber, so that the pressurized gas advances the plunger to guide the piston distally, thereby delivering the one or more agents through the needle.

[0011] Other aspects and features of the present invention will become apparent from the following description considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] It is believed that 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 like elements, and in which:

[0013] Figure 1 is a perspective view of an exemplary automatic injector device including front and rear housings and a safety cap.

[0014] Figure 2A and 2B They are Figure 1 Longitudinal cross-sections of the device taken along orthogonal planes 2A-2A and 2B-2B show the internal components of the device, including a syringe carrying one or more agents.

[0015] Figure 3A and 3B Before use Figure 1-2B Detail of the distal end of the device, showing the safety cap covering the activation cap and needle of the device.

[0016] Figures 4A-4C yes Figure 1-2BA cross-section of a device showing activation of the device when the activation cap is displaced proximally when the device is pressed against the skin of a subject to pierce the skin with a needle, causing the syringe spacer and the release cap to also displace proximally to release the carrier carrying the opener pin, causing the opener pin to be advanced distally to open the gas canister, thereby releasing pressurized gas into the flow path within the device.

[0017] Figures 5A-5C They are Figures 4A-4C Detail of the proximal end of the device shown.

[0018] Fig. 6A and 6B After releasing the pressurized gas Figure 1 -6, showing a cross-section of a device that advances a plunger within the device to deliver one or more agents within a syringe through a needle and to advance an activation cap as the needle is withdrawn from the subject's skin.

[0019] Figure 6C yes Figure 6B Detail of the device shown, showing the activation cap after the tab lock has been pushed in.

[0020] The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be implemented in a variety of other ways, including those not necessarily shown in the drawings. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several aspects of the invention and, together with the description, serve to explain the principles of the invention; however, it should be understood that the invention is not limited to the precise arrangements shown. DETAILED DESCRIPTION

[0021] Before describing the examples, it should be understood that the present invention is not limited to the specific examples described, as they may of course vary. It should also be understood that the terminology used herein is for the purpose of describing specific examples only and is not intended to be limiting, as the scope of the present invention will be limited only by the appended claims.

[0022] Where a numerical range is provided, it will be understood that, unless the context clearly dictates otherwise, each intervening value (to one tenth of the unit of the lower limit) between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any recorded value or intervening value within the recorded range and any other recorded value or intermediate value within the recorded range is included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the range, and each range in which the smaller range includes any limit, does not include two limits, or includes both limits (is also included in the present invention, subject to any specifically excluded limits within the recorded range. Where the recorded range includes one or two limits, ranges excluding either or both of those included limits are also included in the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the 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.

[0024] 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 "a polymer" includes reference to one or more polymers and equivalents thereof known to those skilled in the art, and so forth.

[0025] Certain ranges are given herein where a value is preceded by the term "about". The term "about" is used herein to provide literal support for the exact value that follows it, as well as values ​​that are close to or approximately the value that follows the term. In determining whether a value is close to or approximately a specifically recited value, a close or approximate unrecorded value may be a value that, in the circumstances in which it is placed, provides a substantial equivalence to the specifically recited value.

[0026] Go to the attached picture, Figure 1 An example of an automatic injector device 6 is shown, which includes a housing 8, the housing 8 including a front shell 10 and a rear shell 12, the front shell 10 carrying a syringe 70, the syringe 70 containing one or more agents in an agent chamber 73, and the rear shell 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 shell 10 to prevent premature activation of the device 6, which can be removed immediately before injection, as further described elsewhere herein. One or more internal components of the device 6 can move axially relative to the longitudinal axis 18 when the device 6 is activated, i.e., proximally and / or distally, as further described elsewhere herein.

[0027] In one example, the syringe 70 can be a pre-filled syringe (e.g., formed of glass, plastic, etc.) that is filled with a predetermined volume of an agent, such as a single dose corresponding to a patient. Alternatively, the agent chamber and needle can be integrated into the front shell 10 as needed (not shown). In a further alternative, the syringe 70 (or an integrated agent chamber) can include a distal port (not shown) without a needle, so that a separate needle (also not shown) can be connected to the port immediately before injection or when needed, such as using a Luer fitting, matching threads and / or other mating connectors. As used herein, "agent" can include one or more flowable therapeutic and / or diagnostic compounds, drugs or materials, such as liquid or gaseous form, solutions or suspensions, etc., such as viscous fluids.

[0028] Additional references Figure 2A and 2B , the syringe 70 includes a barrel 72 containing an agent(s) in an 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 a subject's body (not shown). The device 6 also includes a gas tank or other pressurized gas source 40 to provide power to the device 6, for example, 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 tank 40 to release the pressurized gas within the tank 40 into a set of chambers of the device 6. For example, the inner housing 20 can be mounted within the outer housing 8, which includes a first or proximal chamber 22 (e.g., in which the gas tank 40 is mounted) and a second or distal chamber 24 (e.g., in which the plunger 50 is slidably received).

[0029] In general, the device 6 is configured so that when the contact surface 84 of the activation cap 80 is pressed against the skin of the subject to insert the needle 78, the activation cap 80 is retracted proximally into the housing 8 and automatically activates the opener mechanism 60 to release pressurized gas from the canister 40 into the first and second chambers 22, 24, which generates a distal force to advance the plunger 50, thereby delivering the agent(s) from the syringe 70 into the subject. After the injection is completed and the device 6 is withdrawn from the skin, the activation cap 80 can be automatically advanced to cover the needle 78.

[0030] For example, a spacer 30 may be provided that extends between the activation cap 80 and the release cap 34 adjacent the opener mechanism 60, such that proximal movement of the activation cap 80 translates through the spacer 30 to guide the release cap 34 proximally within the rear shell 12, which releases the opener mechanism 60, as further described elsewhere herein. The spacer 30 may be biased distally, such as by a spring 32, which in turn may bias the activation cap 80 distally after the injection is completed, as further described elsewhere herein.

[0031] In general, the housing 8 includes a proximal end 8a (e.g., provided on the rear shell 12), an open distal end 8b (e.g., provided on the front shell 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 can be sized and / or shaped to facilitate manipulation of the device 6, for example, to facilitate placement and pressure of the activation cap 80 against the skin of the subject to activate the device 6 and inject the agent (one or more). For example, the outer surface can have a generally cylindrical shape, optionally including one or more textures or gripping features, so that the operator (the subject himself or a third party) can hold the device 6 in one hand and press the activation cap 80 against the skin of the subject, as further described elsewhere herein. As shown, the proximal end 8a of the shell 8 may include a wall 8c that closes the proximal end 8a, and optionally one or more pockets or other features 8d for locking the release cap 34, as further described elsewhere herein.

[0032] The housing 8 may be formed of a plurality of separate components (e.g., clamshell halves), for example, formed of metal (e.g., stainless steel, aluminum, etc.), plastic, and / or composite materials, by one or more of cold drawing, molding, casting, machining, etc., which are substantially permanently attached together, for example, by one or more of welding, brazing, fusing, bonding with an adhesive, interference fit, etc. As shown, the housing 8 is formed with separate front and rear shells 10, 12, which may be separately assembled with corresponding internal components and then coupled together, for example, after the syringe 70 is loaded into the front shell 10.

[0033] For example, during manufacturing, the front housing 10 can be assembled with the activation cap 80 and the safety cap 86, and the syringe 70 can be loaded into the interior of the front housing 10, such as during manufacturing or during assembly of the device 6 at any time before an injection is performed. Figure 3A and 3B As shown, the syringe 70 may include a rigid needle shield 79 (e.g., formed of conventional materials) that can be removably secured to the distal end 72a of the barrel 72 to protect the needle and prevent accidental sticking. The safety cap 86 may include a feature 86a that engages with the needle shield 79 so 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 fall into one or more corresponding cutouts, recesses, or other features on the needle shield 79 when the syringe 70 is inserted into the front shell 10, thereby coupling the needle shield 79 to the safety cap 86, as described elsewhere herein.

[0034] The rear housing 12 can be assembled with the inner housing 20, the spacer 30, the release cap 34, the gas cylinder 40, the plunger 50, and the opener mechanism 60 (as well as any other accompanying components), and the rear housing 12 can be coupled to the front housing 10 at any time. For example, during the manufacturing process, the syringe 70 can be loaded into the interior of the front housing 10, and the assembled rear housing 12 can be immediately coupled to the front housing 10. When the rear housing 12 is attached to the front housing 10, the distal end 54 of the plunger 50 can be coupled to the piston 74 within the syringe 70, for example, so that the distal movement of the plunger 50 is translated to the piston 74, as further described elsewhere herein.

[0035] like Figure 2A and 2B As shown, the housing 8 may include a mount 11, such as on one of the front 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, such as a radial flange or a pair of opposing flanges, which may abut the mount 11 and / or be received within the mount 11 to secure the syringe 70 relative to the front housing 10. Additionally 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 viewing of the syringe 70 during injection, for example, thereby allowing visual confirmation when the piston 74 is fully advanced.

[0036] Optionally, the device 6 can include a syringe spacer or adapter 75 that can provide an interface between the distal end 54 of the plunger 50 and the piston 74, for example, to provide a connector therebetween and / or ensure proper spacing so that the piston 74 is advanced with the plunger 50. For example, spacers 75 of varying lengths can be provided to allow syringes of varying lengths to be loaded into the front housing 10 while properly positioning the needle 78 adjacent the distal end 8 b of the housing 8 and allowing the plunger 50 to be properly coupled to the piston 74.

[0037] During manufacture or assembly, a syringe 70 may be selected that can be inserted into the housing 8, such as through an 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, such as through one or more mating threads (as shown), one or more bayonet pins, or other connectors, etc. When the rear housing 12 is coupled to the front housing 10, the distal end 54 of the plunger 50 may be inserted into the recess 75b in the syringe spacer 75. Optionally, the distal end 54 and the recess 75b of the plunger 50 may include mating locking features, such as one or more threads, bayonet pins, etc. (not shown), or the distal end 54 may simply be inserted into the recess 75b to couple subsequent distal movement of the piston 74 to the plunger 50, as further described elsewhere herein.

[0038] Alternatively, the assembled housings 10, 12 may be packaged, stored, and / or otherwise prepared for subsequent assembly. For example, the housings 10, 12 may be shipped or otherwise provided to a manufacturer of the syringe 70, which may load the syringe 70 and couple the housings 10, 12 together to provide the completed 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 prior to performing an injection, which may allow a syringe including a specific dose to be loaded prior to injection.

[0039] The proximal end 10a of the front shell 10 and the distal end 12b of the rear shell 12 may include one or more mating connectors (not shown) to couple the shells 10, 12 together to provide a fully assembled device 6. For example, the shells 10, 12 may include one or more mating threads, bayonet pins, etc., which may permanently couple the shells 10, 12 together. Alternatively, the connectors may allow the shells 10, 12 to be subsequently separated, such as after performing an injection, to remove the syringe 70, such as to allow the device 6 to be cleaned and reused with a new syringe.

[0040] Additionally or alternatively, the shells 10, 12 may be permanently attached together by one or more of an interference fit between the ends 10a, 12b, adhesive bonding, fusion, sonic welding, etc. In another alternative, the 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 in the case of a two-part housing, the device 6 may be a single-use device that may be disposed of after a single injection.

[0041] exist Figure 2A and 2BIn the example shown, the inner shell 20 includes a proximal cylinder 20a and a distal cylinder 20b, the proximal cylinder 20a including a first chamber 22 and the distal cylinder 20b including a second chamber 24. Each of the proximal and distal cylinders 20a, 20b can have an elongated cylindrical wall or other cross-sectional shape along its length. The proximal and distal cylinders 20a, 20b can be permanently attached together to provide the inner shell 20 (e.g., by one or more of the following: mating threads (as shown), bayonet or other connectors, press fit, adhesive bonding, sonic welding, melting, etc.). Alternatively, the inner shell 20 can be formed as a single integral structure including the first and second chambers 22, 24. The proximal and distal cylinders 20a, 20b can be formed of a material similar to or different from the outer shell 8.

[0042] The inner shell 20 may be mounted within the outer shell 8 such that the inner shell 20 remains substantially stationary within the outer shell 8. Similarly, the gas tank 40 may be mounted within the inner shell 20, such as within the first chamber 22, such that the gas tank 40 also remains substantially stationary relative to the outer shell 8. For example, one or more struts, supports, or other structures (not shown) may be provided on the inner shell 20 and / or the outer shell 8 to secure the inner shell 20 and / or the gas tank 40 relative to the outer shell 8.

[0043] In the example shown, the proximal cylinder 20a can include an annular wall surrounding the first chamber 22, including a uniform diameter first region 22a in which the gas cylinder 40 is mounted, and second and third regions 22b, 22c in which the opener mechanism 60 is slidably mounted, as further described elsewhere herein. The length of the distal cylinder 20b can be such that when the device 6 is assembled, the distal end 21b of the distal cylinder 20b can be adjacent to the syringe 70.

[0044] Optionally, the distal end 21b may include one or more features that contact the proximal end 72b of the syringe 70, such as an O-ring 20d formed of an elastic and / or relatively flexible material fixed on or around the distal end 21b. The O-ring 20d can prevent the distal end 21b from damaging the syringe 70, for example, if the barrel 72 is made of glass.

[0045] Continue to refer Figure 2A and 2B, 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 outlet end 42b to provide a closed chamber 48 filled with a fluid comprising a pressurized gas (e.g., carbon dioxide or a fluorocarbon gas) compressed to a pressure sufficient to at least partially liquefy the gas within chamber 48. Alternatively, a fluid comprising a gas such as argon, nitrogen, helium, or other combinations thereof that remains in a gaseous form may be stored within chamber 48. As described elsewhere herein, the pressurized fluid contained within chamber 48 may be used to generate a force to operate device 6, for example, to inject one or more agents from syringe 70 into the body of a subject.

[0046] In one example, the body 42 and cap 44 can be formed from stainless steel or other desired or suitable metal, plastic, or composite material, such as by one or more of drawing, stamping, machining, casting, molding, etc. For example, the body 42 can be deep drawn from sheet metal (e.g., a rounded sheet metal blank of Type 305 stainless steel) using one or more dies and punches (not shown) to form a main barrel region, a closed end 42a, an optional tapered shoulder region, and an outlet end 42b - defining an opening to which the cap 44 is attached.

[0047] As shown, the tank 40 can be oriented with the outlet end 42b proximal to the closed end 42a, and an opener mechanism 60 can be provided proximal to the outlet end 44. In the example shown, the cap 44 can be a closed cap including a diaphragm or other weakened area (not shown) that can be opened by an opener mechanism. In this example, the opener mechanism can include an opener pin 62 that is configured to pierce or preferably tear the diaphragm, as described elsewhere herein. Other information about usable tanks and methods of making them can be found in U.S. Publication No. 2017 / 0258583, the entire disclosure of which is expressly incorporated herein by reference.

[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 the outlet in the cap 44 but may be directed by the opener mechanism 60 away from the cap 44 (e.g., into the canister 40) 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) that is sized to enter the outlet and push the closer away from the outlet.

[0049] The plunger 50 may be an elongated rod or other member including a proximal end 52 slidably disposed within the second chamber 24 (e.g., initially proximate the first chamber 22), and a distal end 54 coupled to the piston 74. The plunger 50 is retracted from an initial or retracted position (e.g., Figure 2A and 2B7A and 7B ) to a final or extended position (eg, as shown in FIGS. 7A and 7B ), for example, wherein the distal end 54 extends from the second end 16 of the drive assembly 12 into the dosage chamber 73 of the syringe 70.

[0050] A flange or other guide member 53 may be provided on the proximal end 52 of the plunger 50 that slidably engages the wall of the second chamber 24. Thus, when pressurized gas enters the second chamber 24 (via the first chamber 22), the pressure generates a distal force to guide the plunger 50 distally from the initial position toward the final position, thereby advancing the piston 74 and delivering one or more agents from the agent chamber 73 through the needle 78 into the subject, as further described elsewhere herein.

[0051] 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 the pressure rise time within the second chamber 24. For example, the intermediate passage may i) slow the transient flow of gas, slowing the rise in pressure applied to the plunger 50, for example, to provide a soft start for injection, reducing / eliminating pressure shock fluctuations in the fluid to be injected in the syringe, and possibly reducing pain for the patient because the drug injection is gently initiated; and / or ii) slow the steady state flow of gas, reducing the pressure otherwise applied to the plunger 50, providing a limiting effect on the flow rate of the drug injected into the patient.

[0052] Optionally, as shown, the plunger 50 may also include a plunger chamber 56, for example, extending from the open proximal end 52 of the plunger 50 to the 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 end 52 and the distal end 54.

[0053] Optionally, the flange 53 on the proximal end 52 of the plunger 50 may include one or more channels (not shown) extending between the proximal and distal surfaces of the flange 53. For example, the flange 53 may include a plurality of circular or other closed channels spaced apart from one another around the circumference of the flange 53, each extending between the proximal and distal surfaces.

[0054] In this option, the flange 53 may be sized and / or shaped to slidably engage the inner wall of the second chamber 24, for example, to allow the plunger 50 to move from the initial position to the extended position, but no O-ring or other seal may be required. Instead, one or more O-rings or other seals may be provided within and / or adjacent the inner housing 10 to seal the first and second chambers 22, 24 and / or otherwise the flow path from the gas cylinder 40 to the plunger 50. For example, a first O-ring 58a may be provided between the inner housing 10 and the opener mechanism 60, a second O-ring 58b may be provided between the distal end 21b of the inner housing 10 and the plunger 50, and / or a third O-ring 58c may be provided between the proximal and distal cylinders 10a, 10b (if provided as separate components that are fixed together).

[0055] In one example, the plunger 50 includes a flange 53 formed as a cylindrical head having an outer diameter greater than the plunger 50, which may be integrally molded or otherwise formed with the plunger 50, or which may be separately manufactured and permanently attached to the plunger 50, wherein one or more channels (not shown) extend 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 in the first chamber 22 around the canister 40, the second chamber 24 around the plunger 50, and optionally the plunger chamber 56 may result in an initial pressure drop as the gas fills the available volume. However, as the plunger 50 is advanced, the change in volume that the gas must fill increases only minimally (e.g., the volume occupied by the plunger 50 within the second chamber 24 that is moved out of the distal end 16 of the drive assembly 12). Therefore, due to the minimized volume change, the resulting force applied by the pressure on the plunger 50 can remain substantially constant or only slightly reduced. Thus, the resulting force drop applied to the plunger 50 can be minimized, which can provide a more uniform delivery rate of the dosage form from the syringe 70. Additional information regarding plungers that can provide a reduced pressure drop can be found in co-pending U.S. Application Serial No. 17 / 965,707, the entire disclosure of which is expressly incorporated herein by reference.

[0056] Optionally, the proximal end 52 of the plunger 50 can 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 can taper between the proximal end 52 and the distal end 54 of the plunger 50. This tapering shape can increase the cross-sectional area of ​​the plunger 50 as the plunger 50 advances from the initial position toward the final position, which can minimize the change in the distal force applied to the syringe stopper due to the volume change, which can be particularly useful for applications requiring a consistent delivery rate. It will be understood that any of these optional features associated with the plunger 50 can be combined together or omitted as desired.

[0057] Back to Figure 2Aand 2B , the opener mechanism 60 includes a spring seat or carrier 64, which is slidably coupled to the rear shell 12, such as within the second and third regions 22b, 22c of the first chamber 24. The carrier 64 carries an opener pin 62, which is mounted, for example, along the axis 18 and directed distally toward the cap 44. The carrier 64 and the release cap 34 include one or more features that disengage when the release cap 34 is directed proximally (by activating the cap 80 and the spacer 30), and the carrier 64 can be biased to move distally when released, thereby directing the opener pin distally to open the outlet in the cap 44 of the canister 40.

[0058] For example, the rear housing 12 and the carrier 64 may include mating features that prevent the carrier 64 from moving until the device 6 is activated. Figures 5A-5C As best shown, the carrier 64 includes a locking lug or other feature 64a on its proximal end that engages the proximal end 13a of the rear housing 12, and a flange 64b on its distal end that is slidable within the second region 22b of the first chamber 24. A spring 66 is also provided around the carrier 64 within the second region 22b, for example, a coil spring provided between the rear housing 12 and the flange 64b in an initially compressed state. Thus, the spring 66 biases the carrier 64 to move distally, were it not for the locking feature 64a engaging the proximal end 13a of the rear housing 12.

[0059] The release cap 34 and the carrier 64 include mating features that release the locking feature 64a from the rear housing 12 when the device 6 is activated. Figures 5A-5C As shown, the release cap 34 includes a cylindrical body that surrounds a portion of the rear shell 12, such as the second and third regions 22b, 22c of the first chamber 24. The release cap 34 may also include a closed proximal end 34a, which is proximal to the proximal end 13a of the rear shell 12, and a distal end 34b, which 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 can slide proximally along the inner surface of the housing 8, such as until it abuts against a ridge on the housing 8, to prevent further proximal movement of the release cap 34, as further described elsewhere herein.

[0060] As shown, the central hub 36 is provided on the proximal end 34a of the release cap 34, aligned along the axis 18, distally toward the opener pin 62. The carrier 64 includes a plurality of lugs 65, for example, arranged concentrically around the axis 18, so that the lugs 65 can slide along the hub 36 when the release cap 34 is directed proximally. After the hub 36 moves proximally over the lugs 65, the lugs 65 are biased to move radially inward (toward the central axis 18), thereby directing the locking features 64a inwardly. After the locking features 64a leave the proximal end 13a of the rear shell 12, for example, Figure 5CAs shown, the spring 66 may automatically direct the carrier 64 distally, thereby directing the opener pin 62 distally to pierce a septum in the cap 44 of the canister 40 (or otherwise open an outlet).

[0061] During use, the device 6 may initially be provided with the safety cap 86 attached to the distal end 8b of the housing 8, e.g. Figure 1-2B Before an injection is performed, the safety cap 86 may be removed, for example by simply pulling the safety cap 86 distally away from the housing 8 to expose the contact surface 84 of the activation cap 80, for example Figure 4A For example, Figure 3A and 3B As best shown, the safety cap 86 may include an inner cylindrical member and an outer cylindrical member, wherein a proximal end 86a of the inner member is coupled to the needle shield 79 and a proximal end 86b of the outer member is slidably received on the distal end 8b of the housing 8. Alternatively, the safety cap 86 and / or the housing 8 may include one or more connectors, locks, etc. (not shown) that may be disengaged prior to removing the safety cap 86.

[0062] As described elsewhere herein, the safety cap 86 can prevent the activation cap 80 from being introduced proximally, for example by preventing the activation cap 80 from being touched. Additionally or alternatively, the safety cap 86 can include features that engage with the needle shield 79 so that when the safety cap 86 is removed, the needle shield 79 is also removed. The safety cap 86 and the needle shield 79 can prevent the needle 78 from being exposed from the housing 8 prior to use. After the safety cap 86 and the needle shield 79 are removed, the device 6 is ready for performing an injection.

[0063] Go to Figures 4A-4C , contact surface 84 may be placed against the subject's skin (not shown), and device 6 may then be pressed against the skin to insert needle 78, thereby causing activation cap 80 to be released from the subject as needle 78 enters the subject's skin. Figure 4A The initial position shown to Figure 4B As further described below, this action can activate the opener mechanism 60, causing the opener pin 62 to open the outlet of the gas cylinder 40 to release the pressurized gas into the first chamber 22, which can then advance the plunger 50 and thus the piston 74 to deliver the agent(s) through the needle 78 into the subject's body.

[0064] For example, Figure 4AAs shown, initially, the proximal end 82 of the activation cap 80 may be adjacent to or otherwise engage the distal end 30a of the septum 30, and the proximal end 30b of the septum 30 may be adjacent to or otherwise engage the distal end 34b of the release cap 34. Therefore, when the activation cap 80 is retracted proximally within the housing 8, its proximal end 82 pushes the distal end 30a of the septum 30, thereby guiding the septum 30 proximally, and then the proximal end 30b of the septum 30 pushes the distal end 34b of the release cap 34, thereby guiding the release cap 34 proximally, for example, until the proximal end 34a of the release cap 34 contacts the proximal end 8c of the housing 8.

[0065] As the activation cap 80, the septum 30, and the release cap 34 move proximally, the inner housing 20 (and the canister 40 within the first chamber 22) can remain substantially stationary. Figure 4A and 4B As shown, when the spacer 30 is directed proximally, the spring 32 can be compressed, for example, between the distal end 30a of the spacer 30 and the features on the inner shell 20, thereby biasing the spacer 30 for subsequent distal movement. However, when the operator applies pressure to the contact surface 84 of the activation cap 80 against the skin of the subject, the spacer 30 cannot move distally.

[0066] Because the carrier 64 is fixed relative to the inner shell 20 by the locking feature 64a, the carrier 64 also remains substantially stationary, so that the release cap 34 moves proximally relative to the carrier 64 and the lug 65 on the carrier 64 slides along the hub 36 on the release cap 34, as shown in FIG. Figures 5A-5C When the release cap 34 reaches its most proximal position, e.g. Figure 4C and 5C As shown, the hub 36 has moved proximally past the end of the lug 65, and given the inward bias of the lug 65, the lug 65 is released and automatically moves inward. Given that the lug 65 is coupled to the locking feature 64a on the carrier 64, the inward movement of the lug 65 causes the locking feature 64a to move inward, thereby disengaging the locking feature 64a from the proximal end 21a of the inner shell 20.

[0067] The carrier 64 is then released and biased to move distally due to the spring 66, thereby pushing the opener pin 62 distally to open the outlet of the canister 40, as shown in FIG. Figure 4C and 5C As shown. The release cap 34 may include one or more lugs or other features 34c, for example corresponding to the pockets 8d in the housing 8, so that when the release cap 34 reaches its most distal position, the lugs 34c are received in the corresponding pockets 8d, as shown. Therefore, when the carrier 64 is urged distally due to the spring 66, the lugs 34c can prevent the release cap 34 from moving distally.

[0068] As the carrier 64 moves distally, it causes the opener pin 62 to advance and penetrate the septum in the cap 44 (or otherwise open an 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 reaches the second chamber 24, thereby pressurizing the second chamber 24 to generate a distal force to guide the plunger 50 distally from the initial position toward the final position to deliver the one or more agents from the syringe 70 through the needle 78 into the subject, for example, as Fig. 6A shown.

[0069] The operator can monitor the syringe 70 during the injection, for example through the window (s) 8c, to confirm that the piston 74 has been sufficiently advanced distally within the barrel 72 to deliver the complete dose into the subject. After the injection is complete, the device 6 can 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 septum 30 is automatically advanced distally, thereby directing the activation cap 80 distally to cover the needle 78 when the needle 78 is withdrawn.

[0070] like Figure 6C As shown, when the septum 30 is advanced distally, the proximal end 30b of the septum can pass distally over the feature 34d on the distal end 34b of the release cap 34. For example, the feature 34b can include one or more fingers or lugs that slide along the interior of the septum 30 until the proximal end 30b passes distally, and then the lugs can be elastically moved radially outward, such as so that the lugs 34d are located proximal to the proximal end 30b of the septum 30, thereby preventing subsequent proximal movement of the septum 30. In the case where the septum 30 is prevented from moving proximally, the activation cap 80 can no longer be retracted, thereby locking the activation cap 80 extending over the needle 78 and preventing the needle 78 from being accidentally exposed.

[0071] If the device 6 is a single-use device, the device 6 can then be disposed of. If the device is reusable, for example, if the front shell 10 and the rear shell 12 are separable, the rear shell 12 can be subsequently separated from the front shell 10 and the syringe 70 can be removed. For a reusable device, one or more features can be provided in the device to release any residual pressure in the first and second chambers 22, 24. For example, Fig. 6A and 6B As shown, a gas valve and / or shaft member may be provided within the plunger 50 that can be manipulated to release the pressurized gas before the plunger 50 is removed from the piston 74. The separate outer shells 10, 12 can then be cleaned and / or sterilized, and a new gas cylinder 40 can be loaded into the inner shell 20 before reassembling the device.

[0072] Although the present invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and described in detail herein. However, it should be understood that the present invention is not limited to the specific forms or methods disclosed, but rather, the present invention will cover all modifications, equivalent forms and alternative forms falling within the scope of the appended claims.

Claims

1. A device for delivering one or more agents into a subject, comprising: a 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 the proximal end of the barrel; an inner housing within the outer housing, the inner housing comprising a first chamber adjacent to a proximal end of the outer housing and a second chamber between the first chamber and the proximal end of the barrel; an activation cap on the distal end of the housing such that a contact surface is disposed distal to the distal end of the housing and an activation cap extension extends proximally about the barrel; a source of pressurized gas within said first chamber; a release cap within the housing adjacent the proximal end of the housing, the release cap carrying an opener pin, the opener pin being positioned adjacent the source of pressurized gas; a spacer within the outer shell adjacent to the inner shell, the spacer including a distal end adjacent to the proximal end of the activation cap extension and a proximal end adjacent to the release cap; a plunger including a proximal end within the second chamber and a distal end coupled to the piston of the syringe; and The activation cap is axially movable relative to the housing such that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap is configured to move proximally to direct the septum proximally, the septum thereby directing the release cap proximally to release the opener pin, thereby causing the opener pin to open the pressurized gas source 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, thereby delivering the one or more agents through the needle, The spacer is biased to advance distally so that when the activation cap is released when the contact surface is directed away from the subject's skin after delivery of the one or more agents, the spacer directs the activation cap distally to cover the needle, and the spacer includes one or more locking members to prevent subsequent proximal movement of the spacer and the activation cap.

2. The device of claim 1, wherein the inner housing is axially fixed within the outer housing such that the proximal chamber and the distal chamber do not move relative to the outer housing.

3. The device of claim 1, wherein the proximal portion constitutes a rear shell that carries the inner shell, the release cap, the spacer, the pressurized gas source, and the plunger, the plunger being positioned adjacent to the distal end of the rear shell.

4. The device according to claim 3, wherein: The distal portion constitutes a front shell that carries the activation cap and includes a proximal end including an opening for inserting the syringe into the interior of the front shell; and The proximal end of the front shell and the distal end of the rear shell include mating connectors for securing the front shell and the rear shell together to provide the housing after insertion of the syringe.

5. The device of claim 4, wherein the piston and the plunger include mating connectors such that when the front housing and the rear housing are secured together, distal movement of the plunger directs the piston distally.

6. The device of claim 5, further comprising a syringe spacer between the plunger and the piston.

7. The device of claim 1 , wherein the inner shell comprises a proximal cylinder and a distal cylinder, the proximal cylinder comprising the first chamber, the distal cylinder comprising the second chamber, and wherein the proximal cylinder and the distal cylinder comprise mating connectors for securing the proximal cylinder and the distal cylinder together to provide the inner shell.

8. The device of claim 7, wherein the mating connector comprises one or more of mating male and female threads.

9. The device of claim 1, wherein the inner housing is a unitary cylindrical housing including the first and second chambers.

10. The apparatus of claim 1, wherein the source of pressurized gas comprises a canister, the canister comprising an outlet, and wherein the opener pin is axially movable to open the outlet to release the pressurized gas.

11. The device of claim 10, wherein the gas cylinder includes a pierceable septum that is initially spaced apart from the opener pin, and wherein when the release cap is directed proximally, the opener pin is released such that the opener pin elastically moves axially to penetrate the septum and release the pressurized gas.

12. The device of claim 11, wherein the septum of the gas canister is oriented proximally within the proximal chamber and the opener pin is oriented distally toward the septum.

13. The device of claim 10, wherein the gas cylinder includes a ball sealing the outlet, the ball being initially spaced apart from the opener pin, and wherein when the release cap is guided proximally, the opener pin is released such that the opener pin elastically moves axially to push the ball, thereby opening the outlet and releasing the pressurized gas.

14. The device of claim 13, wherein the opener pin includes one or more features configured to prevent the opener pin from moving away from the gas tank after the outlet is opened.

15. The device according to any one of claims 10-14 further includes a carrier releasably connected to the release cap, the opener pin extending axially from the carrier, the release cap and the carrier including one or more features that disengage when the release cap is guided proximally by the activation cap and the spacer, and the carrier is biased to move axially when released, thereby causing the opener pin to move to open the outlet.

16. The device of claim 15, wherein the inner housing and the carrier include mating features that prevent the carrier from moving proximally when the release cap is directed proximally.

17. The apparatus of claim 15, further comprising a spring mounted between the carrier and the inner housing to bias the carrier to move axially.

18. The device of claim 15, wherein the one or more features include a central hub on a release cap and a plurality of lugs on the carrier that slide along the hub as the release cap is directed proximally until the hub moves proximally past the lugs, the lugs being biased to move radially inward to release the carrier.

19. The apparatus of claim 18, wherein the carrier includes one or more locking features that engage the inner shell to prevent the carrier from moving relative to the inner shell, the locking features being coupled to the plurality of lugs such that when the lugs move radially inward, the one or more locking features disengage from the inner shell and the carrier is then released to move axially.

20. The device according to any one of claims 1-14 further includes a spring connected to the spacer, so that when the activation cap is initially moved proximally, the force in the spring increases as the spacer is guided proximally, thereby providing a distal bias for the spacer when the activation cap is released.

21. The device of any one of claims 1-14, wherein the spacer comprises a cylinder slidably mounted around the inner shell.

22. The device of any one of claims 1-14, further comprising a safety cap connected to the distal end of the shell distal to the activation cap to prevent the activation cap from being directed proximally.

23. The device of any one of claims 1-14, further comprising a safety cap removably connected to the distal end of the housing distal to the activation cap to prevent exposure of the needle from the housing before the safety cap is removed.

24. The device of any one of claims 1-14, wherein the plunger includes a plunger chamber extending from an opening in the proximal end that communicates with the second chamber such that the pressurized gas entering the second chamber fills the plunger chamber.

25. The device of any one of claims 1-14, wherein the housing includes a window that allows viewing of the piston of the syringe.

26. A device for delivering one or more agents into a subject, comprising: a 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 the proximal end of the barrel; an inner housing within the outer housing, the inner housing comprising a first chamber adjacent to a proximal end of the outer housing and a second chamber between the first chamber and the proximal end of the barrel; an activation cap on the distal end of the shell such that a contact surface is disposed distal to the distal end of the shell; a source of pressurized gas within said first chamber; a release cap within the housing adjacent the proximal end of the housing, the release cap carrying an opener pin positioned adjacent the source of pressurized gas, the release cap being operably coupled to the activation cap such that proximal movement of the activation cap directs the release cap proximally; and a plunger including a proximal end within the second chamber and a distal end coupled to the piston of the syringe; The activation cap is axially movable relative to the housing such that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap is configured to retract proximally into the distal end to guide the release cap proximally to release the opener pin, thereby causing the opener pin to open the pressurized gas source to release the pressurized gas into the first chamber and the second chamber, so that the pressurized gas advances the plunger to guide the piston distally to deliver the one or more agents through the needle.

27. A device according to claim 26, wherein the activation cap is biased to advance distally after being retracted proximally, so that when the activation cap is released when the contact surface is directed away from the subject's skin after delivery of the one or more agents, the activation cap advances distally to cover the needle.

28. The device according to claim 26 further includes a spacer between the outer shell and the inner shell, and the spacer extends between the activation cap and the release cap so that when the activation cap is retracted proximally, the activation cap guides the spacer to guide the release cap proximally until the opener pin is released.

29. A device according to claim 28, wherein the spacer is biased distally so that the spacer is guided proximally when the activation cap is retracted proximally, and when the needle is withdrawn from the skin of the subject, the spacer automatically moves distally to guide the activation cap distally to cover the needle, and wherein the spacer includes one or more locking members for preventing subsequent proximal movement of the spacer and the activation cap.

30. The device according to any one of claims 26-29 further includes a carrier releasably connected to the release cap, the opener pin extending axially from the carrier, the release cap and the carrier including one or more features that disengage when the release cap is guided proximally by the activation cap and the spacer, the carrier is released, and the carrier is biased to move axially when released, thereby causing the opener pin to move to open the outlet.

31. A method of delivering one or more agents into a subject, comprising: An injector device is provided, the injector device comprising a housing carrying a syringe comprising a barrel containing one or more agents and a needle extending distally from the barrel such that the tip of the needle is disposed adjacent an activation cap on a distal end of the housing; an inner housing within the housing, the inner housing comprising a first chamber and a second chamber; and a source of pressurized gas within the first chamber; pressing the contact surface of the activation cap against the skin of the subject and inserting the needle into the skin, thereby retracting the activation cap proximally into the housing to cause the carrier carrying the opener pin to be released and advanced to open the outlet of the pressurized gas source into the first chamber and the second chamber, and the pressure from the pressurized gas in the second chamber advances the plunger in the housing to deliver the one or more agents from the barrel through the needle into the subject; and The needle is withdrawn from the subject's skin and the activation cap automatically advances to cover the needle.

32. The method of claim 31 , wherein the source of pressurized gas comprises a tank, the tank comprising an outlet, and wherein when the carrier is released, the opener pin moves axially to open the outlet, thereby releasing the pressurized gas.

33. The method of claim 32, wherein the gas tank includes a pierceable diaphragm that is initially spaced from the opener pin, and wherein when the carrier is released, the opener pin resiliently moves axially to pierce the diaphragm and release the pressurized gas.

34. The method of claim 31 , wherein when the activation cap is proximally retracted, the activation cap proximally directs a release cap to release the carrier.

35. A method according to claim 34, wherein the release cap and carrier include one or more features that disengage to release the carrier when the release cap is guided proximally by the activation cap, and the carrier is biased to move axially when released, thereby moving the opener pin to open the outlet.

36. The method of claim 35, wherein the inner housing and the carrier include mating features that prevent the carrier from moving proximally when the release cap is directed proximally.

37. The method of claim 35, wherein the one or more features include a central hub on the release cap and a plurality of lugs on the carrier, the plurality of lugs sliding along the hub as the release cap is directed proximally until the hub moves proximally past the lugs, the lugs being biased to move radially inward to release the carrier.

38. The method of claim 37, wherein the carrier includes one or more locking features that engage the inner shell to prevent the carrier from moving relative to the inner shell, the locking features being coupled to the plurality of lugs such that when the lugs move radially inward, the one or more locking features disengage from the inner shell and the carrier is then released to move axially.

39. A method according to claim 31, wherein the device further includes a spacer between the outer shell and the inner shell, the spacer extending between the activation cap and a release cap adjacent to the carrier, so that when the activation cap is retracted proximally, the activation cap guides the release cap proximally until the carrier is released, and the carrier is biased to move axially when released, thereby moving the opener pin to open the outlet.

40. A method according to claim 39, wherein the spacer is biased distally so that the spacer is guided proximally when the activation cap is retracted proximally, and when the needle is withdrawn from the skin of the subject, the spacer automatically moves distally to guide the activation cap distally to cover the needle.

41. The method of any one of claims 31-40, further comprising removing a safety cap connected to a distal end of the housing to expose the activation cap before pressing the contact surface against the subject's skin.

42. A method for assembling an injector device, comprising: providing a front shell including a proximal end and a distal end and an activation cap on the distal end such that the contact surface is disposed distally of the distal end; providing a rear shell including a proximal end and a distal end and an interior extending therebetween, the rear shell including a release cap within the interior adjacent the rear shell proximal end, the release cap carrying an opener pin positioned adjacent a source of pressurized gas; and an inner shell within the interior, the inner shell including a first chamber and a second chamber and a plunger, the plunger including a proximal end within the second chamber; loading a syringe into the interior of the front shell such that a needle of the syringe is positioned within the front shell adjacent to the contact surface; and The distal end of the rear shell is connected to the proximal end of the front shell, thereby connecting the plunger to the piston in the syringe, The activation cap is axially movable relative to the front shell so that when the contact surface of the activation cap is pressed against the skin of the subject, the activation cap moves proximally to guide the release cap proximally to release the opener pin, thereby causing the opener pin to open the pressurized gas source to release the pressurized gas into the first chamber and the second chamber, so that the pressurized gas advances the plunger to guide the piston distally, thereby delivering the one or more agents through the needle.

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