Safety caps for injectors and drive systems for auto-injectors

Abstract

Safety caps for injector devices are provided. The injector device may include an injector module including a housing carrying an agent chamber, e.g., a syringe, containing one or more agents, a piston slidably disposed within the agent chamber, and an outlet including a needle and rigid needle shield (RNS) adjacent a. distal end of the housing. The injector device also includes a safety cap that may be connected to the housing to at least partially cover the needle and / or RNS, which includes one or more features that interact with the RNS such that, when the safety cap is subsequently removed, the RNS is also removed to expose the needle before an injection

Description

SAFETY CAPS FOR INJECTORS AND DRIVE SYSTEMS FOR AUTO-INJECTORSRELATED APPLICATION DATA

[0001] The present application claims benefit of co-pending U.S. provisional application Serial No. 63 / 568,290, filed March 21, 2024, the entire disclosure of which is expressly incorporated by reference herein. The present application is related to U.S. Patent Nos. 10,716,892, 10,912,883, and 11,071,824, and U.S. Publication No. 2024 / 0033434, the entire disclosures of which are expressly incorporated by reference herein.TECHNICAL FIELD

[0002] The present application relates generally to devices and methods for delivering agents into a subject’s body and, more particularly, to safety caps for syringes, injectors and / or gas-powered drive systems for injection devices, e.g., that interact with the rigid needle shield (RNS) of a syringe to remove the RNS when the safety cap is removed.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. Such auto-injectors may include a syringe received within an injector housing that includes a rigid needle shield (RNS) covering the needle of the syringe.

[0004] Before the device can be used, the RNS must be removed to allow the needle to be inserted into the subject’s skin. For auto-injectors, the syringe may be positioned in the housing such that the RNS may not be easily removed, e.g., since the RNS may be only partially exposed from the housing.

[0005] Therefore, improved devices and methods for removing a rigid needle shield from a syringe of an injector would be useful.SUMMARY

[0006] The present application relates generally to devices and methods for delivering agents into a subject’s body and, more particularly, to safety caps for syringe,injectors and / or gas-powered drive systems for injection devices, e.g., that interact with the rigid needle shield (RNS) of a syringe to remove the RNS when the safety cap is removed.

[0007] In accordance with one example, an injector device is provided for delivering one or more agents into a patient’s body that includes a housing carrying an agent chamber, e.g., a syringe, containing one or more agents, a piston slidably disposed within the agent chamber, and an outlet including a needle and rigid needle shield (RNS) adjacent a distal end of the housing. The injector device also includes a safety cap that may be connected to the housing to at least partially cover the needle and / or RNS, which includes one or more features that interact with the RNS such that, when the safety cap is subsequently removed, the RNS is also removed to expose the needle before an injection.

[0008] For example, the safety cap may include an outer portion including one or more connectors for connecting the safety cap to the distal end of the housing and an inner portion configured to be received over the RNS and including one or more connectors for coupling to the RNS. In one example, the inner portion may be an annular body shaped to extend over the RNS such that an inner end of the annular body is positioned adjacent a proximal end of the RNS. The inner end may include one or more arms, detents, tabs, and / or other features that interact with the proximal end of the RNS when the safety cap is connected to the housing, e.g., the features engage over or behind the proximal end of the RNS. Consequently, subsequent removal of the safety cap also removes the RNS to expose the needle.

[0009] In accordance with another example, an injector device is provided for delivering one or more agents into a patient’s body that includes a housing comprising a proximal end, a distal end, and a chamber extending between the proximal and distal ends; a syringe received within the chamber containing one or more agents and comprising a piston slidably disposed within the agent chamber, and an outlet including a needle and rigid needle shield, the rigid needle shield positioned adjacent the distal end of the housing when the syringe is loaded into the housing from the proximal end; and a safety cap. The safety cap may include an annular outer portion connected to the distal end of the housing to at least partially cover the needle and rigid needle shield; an inner portion concentrically within the outer portion within which the rigid needle shield is received when the syringe is loaded into the housing; and one or more features on the inner portion that interact with the rigid needle shield when the syringe is loaded into the housing such that, when the safety cap is subsequently removed, the rigid needle shield is also removed to expose the needle.For example, the one or more features may include one or more fingers, arms, detents, or tabs on a proximal end of the inner portion that are located proximal to the proximal end of the rigid needle shield when the syringe is received within the chamber and the safety cap is connected to the housing. In addition or alternatively, the one or more features may include one or more internal features adjacent a distal end of the inner portion that are configured to be received in a recess in the rigid needle shield.

[0010] In the example where the injector device is an auto-injector, the device also includes a drive module within the housing including a plunger coupled to the piston of the injector module to advance the piston to deliver the one or more agents from the agent chamber through the outlet, and a source of energy, e.g., a gas canister for providing pressurized gas to advance the plunger, a spring mechanism, and the like. The injector device may also include an actuator for activating the source of energy to automatically advance the plunger and piston to deliver the one or more agents. Alternatively, the injector device may be a manual device including an actuator that allows a user to control advancement of the plunger and piston during an injection.

[0011] The injector devices herein 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 opening 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 opening mechanism to release the gas.

[0012] 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

[0013] 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:

[0014] FIG. 1 is a perspective view of an exemplary auto-injector device including a front and rear housing, and a safety cap.

[0015] FIGS. 2A and 2B are longitudinal cross-sections of an exemplary autoinjector device showing internal components of the device including a syringe carrying one or more agents.

[0016] FIGS. 3 A and 3B are details of the distal end of the device of FIGS. 2A and 2B before use, showing a safety cap covering an activation cap and needle of the device.

[0017] FIGS. 4A-4C are cross-sections of the device of FIGS. 2A and 2B, showing activation of the device when the activation cap is displaced proximally when the device is pressed against a subject’s skin to puncture the skin with the needle, the activation cap causing a spacer and release cap to also displace proximally to release a carriage carrying an opener pin, causing the opener pin to advance distally to open a gas canister to release pressurized gas into a flow path within the device.

[0018] FIGS. 5A-5C are details of the proximal end of the device as shown in FIGS. 4A-4C, respectively.

[0019] FIGS. 6A and 6B are cross-sections of the device of FIGS. 2A and 2B after the pressurized gas is released, showing the pressurized gas advancing a plunger within the device to deliver one or more agents within the syringe through the needle, and advancing the activation cap when the needle is withdrawn from the subject’s skin.

[0020] FIG. 6C is a detail of the device as shown in FIG. 6B, showing a tab locking the activation cap after being advanced.

[0021] FIG. 7 is a cross-sectional view of a syringe that may be provided in an injector device.

[0022] FIGS. 8A an 8B are side views of exemplary syringes showing exemplary gaps that may be provided between distal ends of the syringes and proximal ends of rigid needle shields covering needles of the syringes.

[0023] FIG. 9 is a perspective view of an exemplary safety cap that may be provided on an injector device to facilitate removal of a rigid needle shield on a syringe of the injector device.

[0024] FIGS. 10A and 10B are cross-sectional views showing the safety cap of FIG. 9 covering a rigid needle shield covering a needle of a syringe.

[0025] FIG. 11 A is a detail of a feature on the safety cap of FIG. 10A configured to engage a proximal end of the rigid needle shield.

[0026] FIG. 1 IB is a detail of an optional feature on the safety cap of FIG. 10B that may interact with the rigid needle shield to improve gripping the rigid needle shield by the safety cap.

[0027] 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

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] In one example, the syringe 70 may be a pre-filled syringe, e.g., formed from glass, plastic, and the like, filled with a predetermined volume of agent, e.g., corresponding to a single dose for a patient. Alternatively, the agent chamber and needle may be integrated into the front housing 10 if desired (not shown). In a further alternative, the syringe 70 (or integral agent chamber) may include a distal port (not shown) without a needle, such that a separate needle (also not shown) may be coupled to the port, e.g., using a Luer fitting, mating threads, and / or other cooperating connectors, immediately before an injection or otherwise as desired. As used herein, “agent” may include one or more flowable therapeutic and / or diagnostic compounds, medicaments, or materials, e.g., in liquid or gaseous form, in solution or suspension, and the like, such as viscous fluids.

[0035] Turning to FIGS 2A and 2B, an exemplary auto-injector device 6 is shown that includes an outer housing 8 including a front housing 10 carrying a syringe 70containing one or more agents within an agent chamber 73, and a rear housing 12 including a drive assembly for automatically delivering the agent(s) from the syringe 70 when the device 6 is activated. As shown, a safety cap 86 is provided on the front housing 10 to prevent premature activation of the device 6, which may be removed immediately before an injection, as described further elsewhere herein. One or more internal components of the device 6 may move axially, i.e., proximally and / or distally relative to the longitudinal axis 18 when the device 6 is activated, as described further elsewhere herein.

[0036] In one example, the syringe 70 may be a pre-filled syringe, e.g., formed from glass, plastic, and the like, filled with a predetermined volume of agent, e.g., corresponding to a single dose for a patient. Alternatively, the agent chamber and needle may be integrated into the front housing 10 if desired (not shown). In a further alternative, the syringe 70 (or integral agent chamber) may include a distal port (not shown) without a needle, such that a separate needle (also not shown) may be coupled to the port, e.g., using a Luer fitting, mating threads, and / or other cooperating connectors, immediately before an injection or otherwise as desired. As used herein, “agent” may include one or more flowable therapeutic and / or diagnostic compounds, medicaments, or materials, e.g., in liquid or gaseous form, in solution or suspension, and the like, such as viscous fluids.

[0037] With continued reference to FIGS. 2 A and 2B, the syringe 70 includes a barrel 72 containing the agent(s) within agent chamber 73, a needle 78 extending from a distal end 72a of the barrel 72, and a piston or stopper 74 slidable within a proximal end 72b of the barrel 72 for directing the agent(s) through the needle 78 into the subject’s body (not shown). The device 6 also includes a gas canister or other source of pressurized gas 40 to power the device 6, e.g., to advance a plunger 50 coupled to the piston 74 to deliver the agent(s). The device 6 also includes an activation cap 80 and an 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, e.g., in which the plunger 50 is slidably received.

[0038] 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 secondchambers 22, 24, which generates a distal force to advance the plunger 50 to deliver the agent(s) from the syringe 70 into the subject. After the injection is completed and the device 6 is withdrawn away from the skin, the activation cap 80 may automatically advance to cover the needle 78.

[0039] 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 direct the release cap 34 proximally within the rear housing 12, which releases a spring perch assembly or carriage 64 of the opener mechanism 60, as described further elsewhere herein. The spacer 30 may be biased distally, e.g., by spring 32, which may, in turn, bias the activation cap 80 distally after completing the injection, also as described further elsewhere herein.

[0040] Generally, the outer housing 8 includes a proximal end 8a, e.g., provided on the rear housing 12, an open distal end 8b, e.g., provided on the front housing 10, and an inner wall extending therebetween to enclose the interior of the device 6. The outer surface between the proximal and distal ends 8a, 8b may be sized and / or shaped to facilitate manipulation of the device 6, e.g., to facilitate placing and pressing the activation cap 80 against a subject’s skin to activate the device 6 and inject the agent(s). For example, the outer surface may have a generally cylindrical shape optionally including one or more textures or grip features to facilitate an operator (the subject themselves or a third party) holding the device 6 in one hand and pressing the activation cap 80 against the subject’s skin, as described further elsewhere herein. As shown, the proximal end 8a of the housing 8 may include a wall 8c enclosing the proximal end 8a and, optionally, one or more pockets or other features 8d for locking the release cap 34, as described further elsewhere herein.

[0041] 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 front and rear housings 10, 12, which may be assembled separately with respective internal components, and then coupled together, e.g., after loading a syringe 70 into the front housing 10.

[0042] For example, during manufacturing, the front housing 10 may be assembled with the activation cap 80 and safety cap 86, and a syringe 70 may be loaded into an interiorof the front housing 10, e.g., during manufacturing or during assembly of the device 6 any time before performing an injection. Optionally, as shown in FIGS. 3A and 3B, the syringe 70 may include a rigid needle shield 79, e.g. formed from conventional materials, that may be removably secured to the distal end 72a of the barrel 72 to protect the needle and prevent accidental sticks. The safety cap 86 may include features 86a that engage the needle shield 79 such that, when the safety cap 86 is removed, the needle shield 79 is also removed. For example, as shown, the proximal end of the safety cap 86 may include one or more fingers 86a that fit into one or more corresponding cutouts, recesses, or other features on the needle shield 79 when the syringe 70 is inserted into the front housing 10, thereby coupling the needle shield 79 to the safety cap 86, as described elsewhere herein.

[0043] 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 front housing 10 at any time. For example, during manufacturing, a syringe 70 may be loaded into the interior of the front housing 10, and the assembled rear housing 12 may be immediately coupled to the front housing 10. When the rear housing 12 is attached to the front housing 10, a distal end 54 of the plunger 50 may be coupled to the piston 74 within the syringe 70, e.g., such that distal movement of the plunger 50 is translated to the piston 74, as described further elsewhere herein.

[0044] As shown in FIGS. 2 A and 2B, the outer housing 8 may include a mount 11, e.g., 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, e.g., a radial flange or a pair of opposing flanges, that may abut and / or be received within the mount 11 to secure the syringe 70 relative to the front housing 10. In addition or alternatively, one or more detents, ridges, or other features (not shown) may be provided on the front housing 10 for securing the syringe 70. Optionally, the front housing 10 may include one or more windows 10c in the sidewall, which may facilitate observing the syringe 70 during an injection, e.g., to allow visual confirmation when the piston 74 is fully advanced.

[0045] Optionally, the device 6 may include a syringe spacer or adapter 75 that may provide an interface between a distal end 54 of the plunger 50 and the piston 74, e.g., to provide connectors therebetween and / or ensure proper spacing such that the piston 74 is advanced in conjunction with the plunger 50. For example, different length spacers 75 maybe provided to allow different length syringes to be loaded into the front housing 10 while properly positioning the needle 78 adjacent the distal end 8b of the outer housing 8 and allowing the plunger 50 to be properly coupled to the piston 74.

[0046] During manufacturing or assembly, a syringe 70 may be selected that may be inserted into the housing 8, e.g., through the opening in the distal end 8b and coupled to the distal end 16 of the drive assembly 12. A syringe spacer 75 may be selected and its distal end 75a may be coupled to the piston 74, e.g., by one or more cooperating threads, as shown, one or more detents or other connectors, and the like. The distal end 54 of the plunger 50 may be inserted into a recess 75b in the syringe spacer 75 when the rear housing 12 is coupled to the front housing 10. Optionally, the distal end 54 of the plunger 50 and the recess 75b may include cooperating locking features, e.g., one or more threads, detents, and the like (not shown) or the distal end 54 may simply be inserted into the recess 75b to couple subsequent distal movement of the piston 74 to the plunger 50, as described further elsewhere herein.

[0047] 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, 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.

[0048] The proximal end 10a of the front housing 10 and the distal end 12b of the rear housing 12 may include one or more cooperating connectors (not shown) to couple the housings 10, 12 together to provide the fully-assembled device 6. For example, the housings 10, 12 may include one or mating threads, detents, and the like, which may permanently couple the housings 10, 12 together. Alternatively, the connectors may allow the housings 10, 12 to be subsequently separated, e.g., after performing an injection, to remove the syringe 70, e.g., to allow the device 6 to be cleaned and reused with a new syringe.

[0049] 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 8may 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.

[0050] 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.

[0051] 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.

[0052] In the example shown, the proximal cylinder 20a may include an annular wall surrounding the first chamber 22 that includes a uniform diameter first region 22a within which the gas canister 40 is mounted, and second and third regions 22b, 22c within which the carriage 64 is slidably mounted, as described further elsewhere herein. The distal cylinder 20b may have a length such that a distal end 21b of the distal cylinder 20b may abut the syringe 70 when the device 6 is assembled.

[0053] Optionally, the distal end 21b may include one or more features that contact the proximal end 72b of the syringe 70, e.g., an O-ring 20d secured on or around the distal end 21b formed from resilient and / or relatively flexible material. The O-ring 20d may prevent the distal end 21b from damaging the syringe 70, e.g., if the barrel 72 is made from glass.

[0054] With continued reference to FIGS. 2 A 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 orotherwise attached to the outlet end 42b to provide an enclosed cavity 48 filled with a fluid containing pressurized gas, such as carbon dioxide or fluorocarbon gases, compressed to sufficient pressure to least partially liquefy the gas within the cavity 48. Alternatively, fluids containing gases such as argon, nitrogen, helium, or other combinations thereof that remain in gaseous form may be stored within the cavity 48. As described elsewhere herein, the pressurized fluid contained within the cavity 48 may be used to generate the forces to operate the device 6, e.g., to inject one or more agents from the syringe 70 into a subject’s body.

[0055] 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.

[0056] 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 42b. 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.

[0057] Alternatively, the cap 44 may include other closure 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.

[0058] The plunger 50 may be an elongate rod or other member including a proximal end 52 that is slidably disposed within the second chamber 24, e.g., initially immediately adjacent the first chamber 22, and a distal end 54 coupled to the piston 74. Theplunger 50 is movable from an initial or retracted position (e.g., shown in FIGS. 2A and 2B) to a final or extended position (e.g., shown in FIGS. 6A and 6B), e.g., wherein the distal end 54 extends from the second end 16 of the drive assembly 12 into the agent chamber 73 of the syringe 70.

[0059] A flange or other guide member 53 may be provided on the proximal end 52 of the plunger 50 that slidably engages a wall of the second chamber 24. Consequently, when pressurized gas enters the second chamber 24 (via the first chamber 22), the pressure generates a distal force to direct the plunger 50 distally from the initial position towards the extended position to advance the piston 74 and deliver the one or more agents from the agent chamber 73 through the needle 78 into the subject, as described further elsewhere herein.

[0060] Optionally, a wall, orifice, or intermediate passage (not shown) may be provided between the first and second chambers 22, 24. The intermediate passage may have a relatively small diameter to provide a restrictor to reduce pressure rise time within the second chamber 24. For example, the intermediate passage may i) slow down the transient flow of gas, slowing the rise of pressure imparted to the plunger 50, e.g., providing a soft-start to the injection, reducing / eliminating pressure shock waves in the fluid to be injected in the syringe and possibly reducing patient pain as the drug injection is gently initiated; and / or ii) slow down the steady state flow of gas, reducing the otherwise pressure imparted to the plunger 50, providing a limiting effect to the flow rate of the drug injected into the patient.

[0061] Optionally, as shown, the plunger 50 may also include a plunger chamber 56, e.g., extending from an open proximal end 52 of the plunger 50 to a closed distal end 54. The plunger chamber 56 may taper inwardly from the proximal end 52 to the distal end 54, as shown, or may have a uniform diameter or other cross-sectional shape along its length. Alternatively, the proximal end 52 of the plunger 50 may include a closed wall and / or the plunger 50 may be a solid rod between the proximal and distal ends 52, 54.

[0062] Optionally, the flange 53 on the proximal end 52 of the plunger 50 may include one or more passages (not shown) that extend between proximal and distal surfaces of the flange 53. For example, the flange 53 may include a plurality of circular or other enclosed passages spaced apart from one another around a circumference of the flange 53, each extending between the proximal and distal surfaces.

[0063] In this option, the flange 53 may be sized and / or shaped to slidably engage an inner wall of the second chamber 24, e.g., to allow the plunger 50 to move from the initial to the extended position but may not require O-rings or other seals. Instead, one or more O-rings or other seals may be provided within and / or adjacent the inner housing 20 to seal the first and second chambers 22, 24 and / or otherwise a flow path from the gas canister 40 to the plunger 50. For example, a first O-ring 58a may be provided between the inner housing 20 and the carriage 64, a second O-ring 58b may be provided between a distal end 21b of the inner housing 20 and the plunger 50, and / or a third O-ring 58c may be provided between the proximal and distal cylinders 10a, 10b, if provided as separate components secured together.

[0064] In one example, the plunger 50 includes a flange 53 formed as a cylindrical head having a larger outer diameter than the plunger 50, which may be integrally molded or otherwise formed with the plunger 50, or that is manufactured separately and permanently attached to the plunger 50, with one or more passages (not shown) extending between the proximal and distal surfaces of the flange 53. When the canister 40 is opened to release the pressurized gas, the initial volume that the gas must fill the first chamber 22 around the canister 40, the second chamber 24 around the plunger 50 and, optionally, the plunger chamber 56, which may result in an initial pressure drop as the gas fills the available volume. However, as the plunger 50 advances, the change in volume that the gas must fill increases only minimally (e.g., the volume the plunger 50 occupies within the second chamber 24 that is displaced out of the distal end 16 of drive assembly 12). Consequently, because the volume change is minimized, the resulting force applied by the pressure on the plunger 50 may remain substantially constant or reduce only slightly. Thus, the resulting force drop applied to the plunger 50 may be minimized, which may provide a more uniform delivery rate of the agent from the syringe 70. Additional information regarding plungers that may provide reduced pressure drop can be found in co-pending U.S. application, Serial Nos. 17 / 965,707, the entire disclosure of which is expressly incorporated by reference herein.

[0065] Optionally, the proximal end 52 of the plunger 50 may have a larger diameter or other cross-section than the distal end 54 of the plunger 50. For example, the outer diameter or cross-section may taper between the proximal and distal ends 52, 54 of the plunger 50. Such a tapered shape may increase the cross-sectional area of the plunger 50 as it advances from the initial position towards the extended position, which may minimize thechange in the distal force applied to the syringe stopper due to volume change, which may be particularly useful for applications where consistent rates of delivery are desired. It will be appreciated that any of these optional features related to the plunger 50 may be combined together or omitted, as desired.

[0066] Returning 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. 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.

[0067] For example, the rear housing 12 and the carriage 64 may include cooperating features that prevent the carriage 64 from moving until the device 6 is activated. For example, as best seen in FIGS. 5A-5C, the carriage 64 includes locking tabs or other features 64a on its proximal end that engage the proximal end 13a of the rear housing 12, and a flange 64b on its distal end slidable within the second region 22b of the first chamber 24. A puncture spring 66 is also provided within the second region 22b around the carriage 64, e.g., a coil spring provided in an initially compressed state between the rear housing 12 and the flange 64b. Consequently, the spring 66 biases the carriage 64 to move distally, but for the locking features 64a engaging the proximal end 13a of the rear housing 12.

[0068] The release cap 34 and carriage 64 include cooperating features that release the locking features 64a from the rear housing 12 when the device 6 is activated. For example, as shown in FIGS. 5A-5C, the release cap 34 includes a cylindrical body surrounding a portion of the rear housing 12, e.g., around the second and third regions 22b, 22c of the first chamber 24. The release cap 34 may also include an enclosed proximal end 34a proximal to the proximal end 13a of the rear housing 12, and a distal end 34b that includes one or more features to limit axial movement of the release cap 34. For example, one or more flanges on the distal end 34b may slide proximally along the inner surface of the outer housing 8, e.g., until they abut a ridge on the outer housing 8 to prevent further proximal movement of the release cap 34, as described further elsewhere herein.

[0069] As shown, a central hub 36 is provided on the proximal end 34a of the release cap 34 aligned along the axis 18 distally towards the opener pin 62. The carriage 64includes a plurality of tabs or release fingers 65, e.g., arranged concentrically around the axis 18 such that the tabs 65 may slide along the hub 36 as the release cap 34 is directed proximally. Once the hub 36 moves proximally beyond the tabs 65, the tabs 65 are biased to move radially inwardly (towards the central axis 18), thereby directing the locking features 64a inwardly. Once the locking features 64a clear the proximal end 13a of the rear housing 12, e.g., as shown in FIG. 5C, the spring 66 may automatically direct the carriage 64 distally, thereby directing the opener pin 62 distally to penetrate the septum in the cap 44 of the canister 40 (or otherwise opening the outlet).

[0070] During use, the device 6 may be provided initially with the safety cap 86 attached to the distal end 8b of the housing 8, e.g., as shown in FIGS. 1-2B. Immediately before performing an injection, the safety cap 86 may be removed, e.g., by simply pulling the safety cap 86 distally away from the outer housing 8, to expose the contact surface 84 of activation cap 80, e.g., as shown in FIG. 4A. For example, as best seen in FIGS. 3A and 3B, the safety cap 86 may include inner and outer cylindrical members with the proximal end 86a of the inner member coupled to the needle shield 79 and a proximal end 86b of the outer member slidably received over the distal end 8b of the outer housing 8. Alternatively, the safety cap 86 and / or outer housing 8 may include one or more connectors, locks, and the like (not shown) that may be disengaged before removing the safety cap 86.

[0071] As described elsewhere herein, the safety cap 86 may prevent the activation cap 80 from being directed proximally, e.g., by preventing the activation cap 80 from being contacted. In addition or alternatively, the safety cap 86 may include features that engage the needle shield 79 such that, when the safety cap 86 is removed, the needle shield 79 is also removed. The safety cap 86 and needle shield 79 may prevent the needle 78 from being exposed from the housing 8 prior to use. Once the safety cap 86 and needle shield 79 are removed, the device 6 is ready to be used to perform an injection.

[0072] Turning to FIGS. 4A-4C, the contact surface 84 may be placed against a subject’s skin (not shown) and then the device 6 may be pressed against the skin to insert the needle 78, thereby causing the activation cap 80 to slide proximally from the initial position shown in FIG. 4A to the retracted position shown in FIG. 4B as the needle 78 enters the subject’s skin. As described further below, this action may activate the 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 theplunger 50 and, consequently, the piston 74 to deliver the agent(s) through the needle 78 into the subject.

[0073] For example, as shown in FIG. 4 A, initially, the proximal end 82 of the activation cap 80 may abut or otherwise engage a distal end 30a of the spacer 30, and a proximal end 30b of the spacer 30 may abut or otherwise engage the distal end 34b of the release cap 34. Consequently, when the activation cap 80 is retracted proximally within the outer housing 8, its proximal end 82 pushes the distal end 30a of the spacer 30, thereby directing the spacer 30 proximally, and, in turn, the proximal end 30b of the spacer 30 pushes the distal end 34b of the release cap 34, thereby directing the release cap 34 proximally, e.g., until the proximal end 34a of the release cap 34 contacts the proximal end 8c of the outer housing 8.

[0074] As the activation cap 80, spacer 30, and release cap 34 move proximally, the inner housing 20 (and canister 40 within the first chamber 22) may remain substantially stationary. As can be seen in FIGS. 4A and 4B, as the spacer 30 is directed proximally, the spring 32 may be compressed, e.g., between features on the distal end 30a of the spacer 30 and the inner housing 20, thereby biasing the spacer 30 subsequently to move distally. However, with the operator pressing the contact surface 84 of the activation cap 80 against the subject’s skin, the spacer 30 is unable to move distally.

[0075] Since the carriage 64 is secured relative to the inner housing 20 by the locking features 64a, the carriage 64 also remains substantially stationary, such that the release cap 34 moves proximally relative to the carriage 64 and the tabs 65 on the carriage64 slide along the hub 36 on the release cap 34, as best seen in FIGS. 5A-5C. When the release cap 34 reaches its proximal-most position, e.g., shown in FIGS. 4C and 5C, the hub 36 has moved proximally beyond the ends of the tabs 65 and, given the inward bias of the tabs 65, the tabs 65 are released and automatically move inwardly. Given that the tabs 65 are coupled to the locking features 64a on the carriage 64, the inward movement of the tabs65 causes the locking features 64a to move inwardly, thereby disengaging the locking features 64a from the proximal end 21a of the inner housing 20.

[0076] Due to the spring 66, the carriage 64 is then released and biased to move distally, thereby advancing the opener pin 62 distally to open the outlet of the canister 40, as shown in FIGS. 4C and 5C. The release cap 34 may include one or more tabs or other features 34c, e.g., corresponding to the pockets 8d in the outer housing 8, such that, when the release cap 34 reaches its proximal-most position, the tabs 34c are received in respectivepockets 8d, as shown. Thus, the tabs 34c may prevent the release cap 34 from moving distally as the carriage 64 advances distally due to the spring 66.

[0077] When the carriage 64 moves distally, it causes the opener pin 62 to advance and penetrate the septum in the cap 44 (or otherwise open the outlet), thereby releasing the pressurized gas within the canister 40. The released pressurized gas then enters the first chamber 22, e.g., around the canister 40, and passes to the second chamber 24, thereby pressurizing the second chamber 24 to generate a distal force to direct the plunger 50 distally from the initial position towards its extended position to deliver the one or more agents from the syringe 70 through the needle 78 into the subject, e.g., as shown in FIG. 6A.

[0078] The operator may monitor the syringe 70 during the injection, e.g., via the window(s) 8c to confirm that the piston 74 has fully advanced distally within the barrel 72 to deliver the entire dose into the subject. Once the injection is completed, the device 6 may be directed away from the subject, thereby withdrawing the needle 78 from the subject’s skin. As the device 6 is directed away from the subject’s skin, the activation cap 80 is free to move distally and, due to the distal bias of the spring 32, the spacer 30 automatically advances distally, thereby directing the activation cap 80 distally to cover the needle 78 as it is withdrawn.

[0079] As best seen in FIG. 6C, as the spacer 30 advances distally, the proximal end 30b of the spacer may pass distally beyond features 34d on the distal end 34b of the release cap 34. For example, the features 34b may include one or more fingers or tabs that slide along the interior of the spacer 30 until the proximal end 30b passes distally, whereupon the tabs may resiliently move radially outwardly, e.g., such that the tabs 34d are located proximal to the proximal end 30b of the spacer 30, thereby preventing the spacer 30 from subsequently moving proximally. With the spacer 30 prevented from moving proximally, the activation cap 80 is unable to retract again, thereby locking the activation cap 80 extended over the needle 78 and preventing accidental exposure of the needle 78.

[0080] If the device 6 is a single-use device, the device 6 may then be disposed of. If the device is reusable, e.g., if the forward and rear housings 10, 12 are separable, the rear housing 12 may subsequently be separated from the front housing 10, and the syringe 70 may be removed. For a reusable device, one or more features may be provided within the device to release any residual pressure within the first and second chambers 22, 24. For example, as shown in FIGS. 6A and 6B, a gas valve and / or shaft member may be provided within the plunger 50, which may be manipulated to release the pressurized gas beforeremoving decoupling the plunger 50 from the piston 74. The separate housings 10, 12 may then be cleaned and / or sterilized and a new gas canister 40 may be loaded into the inner housing 20 before reassembling the device.

[0081] Turning to FIG. 7, a cross-section of a conventional syringe 70 is shown, which may be provided in an injector device, such as the injector device 6 described above (or injectors disclosed in the patents incorporated by reference herein). As described previously, the syringe 70 includes a barrel 72 containing one or more agents within an agent chamber 73, a needle 78 extending from a distal end or hub 72a of the barrel 72, and a piston or stopper (not shown) 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). As shown, the syringe 70 also includes 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.

[0082] FIGS. 8 A and 8B are side views of exemplary syringes 70’, 70b”, which are generally similar to syringe 70, and include a rigid needle shield 79’, 79” attached to the distal end 72a’, 72a” to cover the needle (not shown) of the syringes 70’, 70”. As shown, a gap G’, G” between the barrel 72’, 72” and a proximal end 79a’,” of the rigid needle shield 79’, 79”, which may complicate providing a mechanism for removing the rigid needle shield 79’, 79” before performing an injection. The gap G’, G” may vary based on various parameters, e.g., depending on the particular dimensions of an individual manufacturer of the syringes 70’, 70” and / or rigid needle shield 79’, 79”. For example, the distal end or hub 72a’, 72a” on the syringe 70’, 70” may have different axial lengths, diameters, and / or tapers such that, when the rigid needle shield 79’, 79” is securely seated on the distal end 72a’ 72a”, the gap G’, G” between the barrel 72’, 72” and the proximal end 79a’ 79a” of the rigid needle shield 79’, 79” may vary as shown. In the examples shown in FIGS. 8A and 8B, the rigid needle shield 79’, 79” includes a closed distal end 79b’, 79b” that includes a flat disk 79c’, 79c” and a taper 79d’ 79D’ immediately proximal to the disk 79c’ 79c”, thereby providing an annular groove proximal to the disk 79c’, 79c”.

[0083] It would be useful to provide a safety cap on an injector device that may interact with the rigid needle shield of any syringes, e.g., syringes 70’, 70”, e.g., to facilitate removal of the rigid needle shield 79’, 79” before performing an injection using the injector device. For example, turning to FIG. 9, an exemplary safety cap 186 is shown, which may be constructed generally similar to the safety cap 86 of the injector device 6 shown in FIGS.1-6. The safety cap 186 includes an annular outer sidewall 186b, e.g., having a substantially uniform diameter, and a collar or relatively larger diameter proximal region 186c sized to fit over the distal end of an injector module (not shown), e.g., over the distal 8b of the outer housing 8 of the injector device 6, as shown in FIGS. 2 A and 2B.

[0084] The safety cap 186 also includes a distal end 186d including a tubular inner extension 186e, e.g., that extends axially and concentrically within the outer sidewall 186a. For example, the distal end 186d may include a closed annular wall extending between a distal end 186f of the inner extension 186e and the outer sidewall 186b. As with the safety cap 86 shown of the device 6 (best seen in FIGS. 3 A and 3B), a proximal end 186g of the inner extension 186e includes one or more features 186a that are configured to engage needle shield 79 such that, when the safety cap 186 is removed, the needle shield 79 is also removed. For example, as shown, the proximal end 186g of the inner extension 186e may include one or more fingers, detents, or other features 186a that extend radially inwardly.

[0085] The axial length of the inner extension 186e is set such that, when a syringe 70 is inserted into an injector module including the safety cap 186, the rigid needle shield 79 is positioned within the inner extension 186e, e.g., with the fingers 186a sliding along an outer surface of the rigid needle shield 79 until they pass beyond the proximal end 79a. of the rigid needle shield 79’, whereupon the fingers 186a may resiliently move radially inward behind the proximal end 79a, e.g., as best seen in FIG. 11 A. The fingers 186a may have substantially blunt distal edges configured to engage the proximal end 79a’ of the rigid needle shield 79’. Consequently, if the safety cap 186 is pulled distally, e.g., to remove the safety cap 186 from a housing of an injector module, the fingers 186a pull the rigid needle shield 79’, thereby also removing the rigid needle shield 79’.

[0086] Alternatively, the rigid needle shield may include one or more cutouts, recesses, or other features (not shown), e.g., spaced apart circumferentially from one another around the proximal end of the needle shield 79, into which corresponding fingers may be received when the syringe 70 is inserted into the injector module, thereby affirmatively coupling the needle shield to the safety cap 186, e.g., as described elsewhere herein.

[0087] The length of the inner extension 186e may be sufficiently long to ensure that the fingers 186a pass beyond the proximal end 79a’ of the rigid needle shield 79’ when the syringe 70’ is loaded into the injector module, e.g., whether the gap G’ is shorter, as shown in FIG. 8A, or the gap G” is longer, as shown in FIG. 8B, thereby providing auniversal safety cap 186 that may be used with a variety of configurations of syringes and / or rigid needle shields.

[0088] Optionally, as shown in FIGS. 10B and 1 IB, the safety cap 186 may include one or more internal features, e.g., a continuous annular ridge or a plurality of internal tabs or detents 186h, extending inwardly from the inner extension 186e around the circumference at a location adjacent the distal end 186f of the inner extension 186e, e.g., spaced proximally from the distal end 186d of the safety cap 186. The location may be set such that, when a syringe 70’ is loaded into an injector module including the safety cap 186, the rigid needle shield 79’ may pass through the inner extension 186e until a flat disk 79c’ on the distal end 79b’ of the rigid needle shield 79’ passes through and / or otherwise is positioned distally beyond the feature(s) 186h. Once the syringe 70’ is fully inserted, the feature(s) 186h may enter the recess 79d’ behind the disk 79c’, thereby further coupling the rigid needle shield 79’ to the safety cap 186.

[0089] For example, as best seen in FIG. 1 IB, the internal feature(s) may include an annular ridge 186h including a blunt distal edge and a ramped proximal edge. The ramped proximal edge may accommodate the disk 79c’ passing through the ridge 186h, and, once the ridge 186h is received in the recess 79d’, the blunt distal edge may prevent the disk 79c’ from passing proximally back through the ridge 186h. Thus, the internal feature(s) may further secure the rigid needle shield 79’ to the safety cap 186 such that, when the safety cap 186 is subsequently removed from the injector module, e.g., before performing an injection, the rigid needle shield 79’ is also removed. As shown, the internal feature(s) 186h are provided in addition to the proximal fingers 186a, although, alternatively, the fingers may be omitted from the safety cap such that the internal feature(s) are the only structure coupling the rigid needle shield to the safety cap.

[0090] 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

I CLAIM:

1. An injector device for delivering one or more agents into a patient’s body, comprising: a housing carrying an agent chamber containing one or more agents, a piston slidably disposed within the agent chamber, and an outlet including a needle and rigid needle shield adjacent a distal end of the housing; and a safety cap connectable to the housing to at least partially cover the needle and rigid needle shield, the safety cap comprising one or more features that interact with the rigid needle shield such that, when the safety cap is subsequently removed, the rigid needle shield is also removed to expose the needle.

2. The injector device of claim 1, wherein the agent chamber comprises a syringe received within the housing such that the needle and rigid needle shield are positioned adjacent the distal end of the housing.

3. The injector device of claim 2, wherein the safety cap comprises an outer annular portion including one or more connectors for connecting the safety cap to the distal end of the housing and an inner portion configured to be received over the rigid needle shield.

4. The injector device of claim 3, wherein the one or more features comprise one or more connectors on the inner portion for coupling to the rigid needle shield.

5. The injector device of claim 3, wherein the inner portion comprises an annular body shaped to extend over the rigid needle shield such that a proximal end of the annular body is positioned adjacent a proximal end of the rigid needle shield when the syringe is received in the housing, the proximal end of the annular body comprising the one or more features.

6. The injector device of claim 5, wherein the one or more features comprises one or more fingers, arms, detents, or tabs that interact with the proximal end of the rigid needle shield when the safety cap is connected to the housing such that, subsequent removal of the safety cap also removes the rigid needle shield to expose the needle.

7. The injector device of claim 6, wherein the annular body has a length corresponding to a length of the rigid needle shield such that the one or more fingers, arms, detents, or tabs are located proximal to the proximal end of the rigid needle shield.

8. The injector device of claim 7, wherein the one or more fingers, arms, detents, or tabs are configured to slide along an outer surface of the rigid needle shield when the syringe is inserted into the housing, the one or more fingers, arms, detents, or tabs biased radially inwardly such that the one or more fingers, arms, detents, or tabs move radially inwardly behind the proximal end of the rigid needle shield when the syringe is fully received in the housing.

9. The injector device of any one of claims 5-8, wherein the rigid needle shield comprises a distal end including a recess therein, and wherein the one or more features further comprise one or more internal features within the annular body distal to the one or more features on the proximal end of the annular body that are received within the recess when the syringe is received in the housing.

10. The injector device of claim 9, wherein the distal end of the rigid needle shield includes a flat disk distal to the recess, and wherein the one or more internal features are configured to accommodate the disk passing distally beyond the one or more internal features until the one or more internal features are received in the recess, thereby preventing the disk from moving proximally.

11. The injector device of claim 3, wherein the inner portion comprises an annular body that extends over the rigid needle shield such that a proximal end of the annular body is positioned adjacent a proximal end of the rigid needle shield when the syringe is received in the housing, wherein the rigid needle shield comprises a distal end including a recess therein, and wherein the one or more features comprise one or more internal features within the annular body that are received within the recess when the syringe is received in the housing.

12. The injector device of claim 11, wherein the distal end of the rigid needle shield includes a flat disk distal to the recess, and wherein the one or more internal features are configured to accommodate the disk passing distally beyond the one or more internal features until the one or more internal features are received in the recess, thereby preventing the disk from moving proximally.

13. An injector device for delivering one or more agents into a patient’s body, comprising: a housing comprising a proximal end, a distal end, and a chamber extending between the proximal and distal ends; a syringe received within the chamber comprising an agent chamber containing one or more agents and a piston slidably disposed within the agent chamber, and an outlet including a needle and rigid needle shield, the rigid needle shield positioned adjacent the distal end of the housing when the syringe is loaded into the housing from the proximal end; and a safety cap comprising: an annular outer portion connected to the distal end of the housing to at least partially cover the needle and rigid needle shield; an inner portion concentrically within the outer portion within which the rigid needle shield is received with the syringe is loaded into the housing; and one or more features on the inner portion that interact with the rigid needle shield when the syringe is loaded into the housing such that, when the safety cap is subsequently removed, the rigid needle shield is also removed to expose the needle.

14. The injector device of claim 13, wherein the one or more features comprises one or more fingers, arms, detents, or tabs on a proximal end of the inner portion that interact with the proximal end of the rigid needle shield when the safety cap is connected to the housing and the syringe is loaded into the chamber such that, subsequent removal of the safety cap also removes the rigid needle shield to expose the needle.

15. The injector device of claim 14, wherein the inner portion has a predetermined length corresponding to a length of the rigid needle shield such that the one or more fingers, arms, detents, or tabs are located proximal to the proximal end of the rigid needle shield.

16. The injector device of claim 15, wherein the one or more fingers, arms, detents, or tabs are configured to slide along an outer surface of the rigid needle shield when the syringe is inserted into the housing or the safety cap is connected to the distal end of the housing, the one or more fingers, arms, detents, or tabs biased radially inwardly such that the one or more fingers, arms, detents, or tabs move radially inwardly behind the proximal end of the rigid needle shield to couple the rigid needle shield to the safety cap.

17. The injector device of claim 13, wherein the rigid needle shield comprises a distal end including an annular recess therein, and wherein the one or more features further comprise one or more internal features within the inner portion distal to the one or more features on the proximal end of the inner portion, the one or more internal features received within the recess when the syringe is received in the housing to further couple the rigid needle shield to the safety cap.

18. The injector device of claim 17, wherein the distal end of the rigid needle shield includes a flat disk distal to the recess, and wherein the one or more internal features are configured to accommodate the disk passing distally beyond the one or more internal features until the one or more internal features are received in the recess and to prevent the disk from subsequently moving proximally.

19. The injector device of claim 13, wherein the rigid needle shield comprises a distal end including an annular recess therein, and wherein the one or more features comprise one or more internal features within the inner portion that are received within the recess when the syringe is received in the housing.

20. The injector device of claim 19, wherein the distal end of the rigid needle shield includes a flat disk distal to the recess, and wherein the one or more internal features are configured to accommodate the disk passing distally beyond the one or more internalfeatures until the one or more internal features are received in the recess and to prevent the disk from subsequently moving proximally.

21. The injector device of any one of claims 1-8 and 13-20, further comprising a drive module within the housing comprising: a plunger coupled to the piston of the syringe to advance the piston to deliver the one or more agents from the agent chamber, and a source of energy configured to advance the plunger when activated.

22. The injector device of claim 21, wherein the source of energy comprises a gas canister containing pressurized gas and an actuator for opening the canister to release the pressurized gas to automatically advance the plunger and piston to deliver the one or more agents.

23. The injector device of claim 21, wherein the source of energy comprises a gas canister containing pressurized gas and an actuator for opening the canister to release the pressurized gas allow a user to control advancement of the plunger and piston during an injection.

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