Gas-operated autoinjector and method of use

Abstract

The automatic injector includes a drive assembly in a housing that carries a syringe including a needle adjacent an actuation cap in a distal end of the housing. The drive assembly includes a first chamber that holds a gas canister, a plunger in a second chamber coupled to the syringe, and proximal and distal chambers. The actuation cap is pressed against the subject's skin to direct the drive assembly in a proximal direction, thereby opening an outlet of the canister to release pressurized gas into the first chamber, after which the gas enters the proximal chamber, thereby generating a distal force that advances the drive assembly to direct the needle into the subject, and enters the second chamber, thereby advancing the plunger to deliver the medicament from the syringe into the subject. After the plunger is advanced, the gas enters the distal chamber, thereby generating a proximal force that retracts the drive assembly to return the needle into the housing.

Description

[Technical field]

[0001] The present application relates generally to devices and methods for delivering medicaments into the body of a subject, and more particularly to automatic injectors and / or gas-powered drive systems for injection devices, as well as methods of making and using such devices.

[0002] Related Application Data This application claims the benefit of co-pending U.S. Provisional Application No. 63 / 286,508, filed December 6, 2021, the entire disclosure of which is expressly incorporated herein by reference. [Background technology]

[0003] There are many applications involving the delivery of drugs or other agents into a patient's body, either subcutaneously, intramuscularly, or otherwise. For example, auto-injectors are available that contain a preset dose of an agent that is automatically delivered into the patient's body after application to the patient's skin and actuation. Typically, such auto-injectors are spring-loaded syringes that, upon actuation, release a spring, which generates sufficient force to cause the needle to penetrate the skin and deliver the dose in the syringe. For viscous fluids, the force required to cause the fluid flow may be greater than what a spring-powered system can provide. If a spring is used, a relatively large force must be generated, which requires a spring with a large mass. As a result, such auto-injectors can make significant noise, generate pressure spikes in the syringe that can lead to glass breakage, vibrate, and / or drive the needle into the patient's skin, which can cause pain and / or frighten the user, especially if the patient is performing the injection himself.

[0004] Therefore, improved devices and methods for delivering pharmaceutical agents into the body of a patient would be useful. Summary of the Invention

[0005] The present application relates generally to devices and methods for delivering medicaments into the body of a subject, and more particularly to automatic injectors and / or gas-powered drive systems for injection devices, as well as methods of making and using such devices.

[0006] According to one embodiment, there is provided a device for delivering one or more medicaments into a body of a subject, the device comprising: an outer housing having a proximal end and a distal end; an actuation cap attached to the distal end of the housing, the actuation cap having a contact surface disposed distal to the distal end of the housing; a drive assembly slidable within the housing; a syringe at the distal end of the drive assembly, the needle of the syringe disposed adjacent the actuation cap within the distal end of the housing; a gas canister in a first chamber in the proximal end of the drive assembly; a plunger having a proximal end in a second chamber of the drive assembly and a distal end coupled to a piston of the syringe; and an opening pin adjacent an outlet of the gas canister, the actuation cap being slidable relative to the housing. the actuation cap is movable in a direction parallel to the housing such that, when a contact surface of the actuation cap is pressed against the skin of the subject, the actuation cap moves proximally to direct the drive assembly proximally within the housing such that the opening pin opens the outlet of the gas canister to release pressurized gas into the first chamber, the drive assembly includes a pair of proximal seals sealing a proximal chamber in communication with the first chamber, the proximal seals are configured such that, when the pressurized gas is released, the pressurized gas generates a distal force that advances the drive assembly distally to direct the needle from the distal end of the housing and into the skin of the subject, and the pressurized gas enters the second chamber and directs the plunger distally from an initial position toward a final position to deliver the one or more medicaments from the syringe through the needle and into the subject. Optionally, the drive assembly may also include a pair of distal seals sealing the distal chamber and a passageway that communicates with the second chamber when the plunger reaches a final position, the distal seals being configured such that when pressurized gas enters the distal chambers, the pressurized gas generates a proximal force that retracts the drive assembly proximally and returns the needle back into the distal end of the housing.

[0007] In another embodiment, a device for delivering one or more medicaments into a body of a subject is provided, the device comprising: an outer housing including a proximal end and a distal end; an actuation cap attached to the distal end of the housing, the actuation cap having a contact surface disposed distal to the distal end of the housing; a drive assembly slidable within the housing; a syringe at the distal end of the drive assembly, the needle of the syringe disposed adjacent to the actuation cap within the distal end of the housing; a gas canister within a first chamber within the proximal end of the drive assembly; a plunger including a proximal end within a second chamber of the drive assembly and a distal end coupled to a piston of the syringe; and a plunger adjacent an outlet of the gas canister. and an opening pin that contacts the first chamber and the second chamber, the actuation cap being movable relative to the housing such that when a contact surface of the actuation cap is pressed against the subject's skin, the actuation cap moves proximally to direct the drive assembly proximally within the housing, causing the opening pin to open an outlet of the gas canister to release pressurized gas into the first chamber, the drive assembly having a pair of distal seals that seal the distal chamber and a passage that communicates with the second chamber when the plunger reaches a final position, the distal seals being configured such that when the pressurized gas enters the distal chambers, the pressurized gas generates a proximal force that retracts the drive assembly proximally and returns the needle into the distal end of the housing.

[0008] According to yet another embodiment, there is provided a method for delivering one or more medicaments into a body of a subject, the method including the steps of providing an injection device including an outer housing having a proximal end and a distal end, an actuation cap attached to the distal end of the housing, the actuation cap having a contact surface disposed distal to the distal end of the housing, a drive assembly slidable within the housing, a syringe at the distal end of the drive assembly, a needle of the syringe disposed adjacent the actuation cap within the distal end of the housing, a gas canister in a first chamber within the proximal end of the drive assembly, a plunger having a proximal end within a second chamber of the drive assembly and a distal end coupled to a piston of the syringe, and a plunger having a proximal end within a second chamber of the drive assembly and a distal end coupled to a piston of the syringe adjacent an outlet of the gas canister. and an opening pin for opening the gas canister, pressing the contact surface against the skin of the subject, and pushing the device to move the actuation cap proximally to direct the drive assembly proximally within the housing, causing the opening pin to open the outlet of the gas canister and release pressurized gas into the first chamber, where the pressurized gas then enters a proximal chamber of the drive assembly sealed by a pair of proximal seals, thereby generating a distal force that advances the drive assembly distally and directs the needle from the distal end of the housing and into the skin of the subject, and the pressurized gas enters a second chamber and directs the plunger distally from the initial position towards a final position, thereby delivering one or more medicaments from the syringe through the needle into the body of the subject. Optionally, when the plunger reaches the final position, the pressurized gas enters a distal chamber sealed by a pair of distal seals, where the pressurized gas generates a proximal force that retracts the drive assembly proximally and returns the needle into the distal end of the housing.

[0009] 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]

[0010] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings, in which: It is emphasized that, according to common practice, the various features and design elements of the drawings are not drawn to scale. Conversely, dimensions of the various features and design elements have been arbitrarily expanded or reduced for clarity. The drawings include the following figures: [Figure 1] 1A and 1B are side and cross-sectional views of an exemplary autoinjector device that includes a drive assembly coupled to a syringe within an outer housing. [Diagram 2] FIG. 2 is a detailed view of the device of FIGS. 1A and 1B with the safety cap removed from the distal end of the housing prior to use. [Diagram 3] 3A and 3B are cross-sectional views of the device of FIGS. 1A and 1B showing an initial operation of the device when gas is released from a gas canister in the drive assembly by pressing the actuation cap against a subject's skin and directing the drive assembly in a proximal direction. [Figure 4] Figures 4A and 4B are detailed views showing how an opening pin opens a gas canister to release pressurized gas, thereby powering the device, and Figure 4C is a detailed view showing an example of an opening pin that includes features that prevent reclosing of the gas canister once it has been opened. [Diagram 5] Figures 5A and 5B show the device of Figures 3A and 3B as the pressurized gas advances the drive assembly distally to direct the syringe needle out of the distal end of the housing, and Figure 5C is a detailed view showing the path of the pressurized gas traveling into the proximal chamber sealed by an O-ring that generates the distal force that advances the drive assembly. [Figure 6]FIG 6A is a cross-sectional view of the device of FIGS. 5A and 5B showing how pressurized gas from a gas canister advances a plunger in the drive assembly to deliver one or more medicaments from the syringe. FIG 6B is a detailed view showing example features of the actuation cap and outer housing that engage as the drive assembly advances to prevent distal movement of the actuation cap during advancement of the drive assembly. FIG 6C shows an example of a plunger that may be included in the drive assembly that includes a plunger distal end that is smaller than the plunger proximal end. [Figure 7] Figures 7A and 7B are cross-sectional views of the device of Figure 6A showing the plunger fully advanced distally to open a fluid path to the distal chamber sealed by an O-ring, thereby retracting the drive housing proximally and withdrawing the needle back into the housing. Figure 7C is a detailed view showing an exemplary flow path for delivering pressurized gas into the distal chamber. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Before describing the embodiments, it is to be understood that the invention is not limited to particular embodiments described, as such may, of course, vary, and the scope of the present invention will be limited only by the appended claims. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0012] Where a range of values ​​is given, it is understood that each intervening value between the upper and lower limits of that range, to the tenth of the unit of the lower limit, is also specifically disclosed unless the context clearly dictates otherwise. Each smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in a stated range is encompassed within the invention. The upper and lower limits of such smaller ranges may each be independently included or excluded within the range, and each range is encompassed within the invention, whether or not both or either are included in the smaller range, subject to the specifically excluded limit in the stated range. Where a stated range includes one or both of the limits, ranges excluding either or both of those included limits are also intended to be included within the invention.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled 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 possible exemplary methods and materials are described herein.

[0014] It should 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, a reference to a "compound" includes a plurality of such compounds, and a reference to a "polymer" includes a reference to one or more polymers and equivalents thereof known to those skilled in the art.

[0015] In this specification, certain ranges are indicated by the term "about" before the numerical values. The term "about" is used in this specification to provide literal support for the exact numerical value following the term and for a numerical value close to or close to the numerical value following the term. In determining whether a numerical value is close to or close to a specifically stated numerical value, the close or close unstated numerical value may be a numerical value that provides a substantial equivalent to the specifically stated numerical value in the context in which it is presented.

[0016] 1A and 1B show an example of an autoinjector device 6 including an outer housing 8, a drive assembly 12 movably housed within the housing 8 that includes a gas canister or other source of pressurized gas 40 for powering the device 6, a syringe 70 including a needle 78 for delivering one or more medicaments into the body of a subject, and a plunger 50. The device 6 also includes an actuation cap 80 and an opener mechanism 60 for opening the canister 40 to release the pressurized gas within the canister 40 into a series of chambers of the device 6. In general, the drive assembly 12 is configured such that, upon actuation by the actuation cap 80, pressurized gas is released from the canister 40 into the chamber of the device 6 to advance the drive assembly 12 and direct the needle 78 into the subject's skin, create a distal force to advance the plunger 50 and deliver one or more medicaments from the syringe 70 into the subject's body, and create a proximal force to retract the drive assembly 12 and return the needle 78 into the housing 8 after the plunger 50 has advanced. Thus, once the actuation cap 80 actuates the device 6, the entire operation is performed automatically by the release of pressurized gas without further operator interaction. As used herein, an "agent" may include one or more therapeutic and / or diagnostic compounds or materials, such as, for example, in liquid or gas form, in solution or suspension, and in viscous fluids.

[0017] Generally, the outer housing 8 includes a proximal end 8a, a distal end 8b, and an inner wall 10a, 10b extending therebetween. The outer surface between the proximal and distal ends 8a, 8b can be sized and / or shaped to facilitate operation of the device 6, such as facilitating placement and pressing of the actuation cap 80 against the skin of a subject to activate the device 6 to inject one or more medicaments. For example, the outer surface can have a generally cylindrical shape, optionally including one or more textures or gripping features, to facilitate an operator holding the device 6 in one hand and pressing the actuation cap 80 against the skin, as further described elsewhere herein. As shown, the proximal end 8a of the housing 8 can include a wall 8c surrounding the proximal end 8a, including a vent 8d to allow air to enter and exit the housing 8 as needed to avoid interference with the movement of the drive assembly 12.

[0018] The housing 8 may be formed from multiple separate components, e.g., clamshell halves, formed from metals such as steel, aluminum, plastics, and / or composites by one or more of cold drawing, molding, casting, machining, and the like, that are substantially permanently attached to one another by one or more of welding, soldering, fusing, adhesive bonding, interference fitting, and the like. Alternatively, the housing 8 may be formed as a single integral component. For example, as shown, the housing 8 may include a first portion 9a including a proximal end 8a including an inner wall 10a, and a second portion 9b permanently attached to the first portion 9a including a distal end 8b including an inner wall 10b having a larger cross-section than the inner wall 10a. As further described elsewhere herein, each inner wall 10a, 10b may have multiple regions having different substantially uniform inner diameters or other cross-sections that cooperate with seals on the drive assembly 12 to generate the forces necessary to guide the drive assembly 12 distally and proximally during operation of the device 6.

[0019] Drive assembly 12 includes proximal and distal ends 14, 16 aligned along a longitudinal axis 18, and drive assembly 12 can move distally and proximally along axis 18 within housing 8 during operation of device 6, e.g., as described elsewhere herein. Drive assembly 12 can be formed as a single, integral component from metals, such as steel, aluminum, plastics, and / or composite materials, e.g., by one or more of cold drawing, molding, casting, machining, etc. Alternatively, drive assembly 12 can be formed from multiple separate components that are substantially permanently attached to one another, e.g., by one or more of welding, soldering, fusing, adhesive bonding, interference fitting, etc.

[0020] 1B, the drive assembly 12 may be formed as a first or proximal portion 20 adjacent the proximal end 14 defining a first chamber 22 for receiving the canister 40, and a separate second or distal portion 24 adjacent the distal end 16 defining a second chamber 26 in communication with the first chamber 22 for receiving the plunger 50. Both housing portions 20, 24 may have a generally cylindrical or other suitable shape, for example, defining one or more additional chambers or regions spaced along the length of the drive assembly 12, as described further below. The proximal and distal portions 20, 24 may be permanently connected to one another, for example, by one or more of mating threads 25, a press fit, adhesive bonding, sonic welding, fusion bonding, or the like.

[0021] For example, the proximal portion 20 can include an annular wall surrounding the first chamber 22 including a first region 22a of uniform diameter, a tapered region 22b, and a second region 22c of uniform diameter sized to accommodate the canister 40 while allowing pressurized gas released from the canister 40 to pass distally around the canister 40 and into the second chamber 24. Additionally, the proximal portion 20 can include one or more passages 28 extending through the annular wall, e.g., a pair of passages 28 extending between the annular wall regions 22b, 22c and the inner wall 10a of the housing 8, that extend through the second region 22c into a proximal chamber 30 surrounding a portion of the proximal portion 20. The drive assembly 12 can include a proximal hub 14a proximal to the first chamber 20, e.g., coupled to the annular wall, the hub 14a extending outwardly to the inner wall 10a of the housing 8.

[0022] 4A-4C, the canister 40 includes a body 42 having a first closed end 42a, a second outlet end 42b, and a cap 44 having a closure 46 welded or otherwise attached to the outlet end 42b, thereby providing a sealed cavity 48 filled with a fluid including a liquefied gas, such as carbon dioxide or a fluorocarbon gas, compressed to a pressure sufficient to at least partially liquefy the gas in the cavity 48. Alternatively, a fluid that remains in a gaseous state may be stored in the cavity 48, including a gas such as argon, nitrogen, helium argon, or other combinations thereof. As described elsewhere herein, the pressurized fluid contained within the cavity 48 may be used to generate a force to operate the device 6, for example, to inject one or more medicaments into the subject's body from a syringe 70.

[0023] 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., by one or more of drawing, stamping, machining, casting, molding, etc. For example, the body 42 may be deep drawn from a round sheet metal blank, e.g., 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 that defines an opening through which the cap 44 is attached.

[0024] In the example shown in FIGS. 4A-4C, the closure 46 is a ball or other member that is biased or otherwise configured to close the outlet of the cap 44, but is directed by an opener mechanism 60 away from the cap 44, e.g., into the canister 40, to open the outlet and release the pressurized gas in the cavity 48. In this example, the opener mechanism 60 includes an opening pin 62 extending through the proximal hub 14a of the drive assembly 12, the opening pin including a proximal or first end 62a disposed adjacent the closed proximal wall 8c of the housing 8, and a distal end 64 disposed adjacent the cap 44, e.g., including a tapered tip 64a sized to enter the outlet and push the closure 46 out of the outlet. For example, the proximal end 62a of the opening pin 62 can abut the proximal end 8c of the housing 8 to prevent proximal movement of the opening pin 62, e.g., when the drive assembly 12 is directed proximally. As a result, when the drive assembly 12 is initially directed proximally, the canister 40 is directed proximally, thereby allowing the tip 64a of the opening pin 62 to enter the outlet and push the closure 46 out of the cap 44 and into the outlet end 42b, thereby releasing the pressurized gas.

[0025] Optionally, as shown in FIG. 4C , the opening pin 62 may include one or more features configured to prevent the opening pin 62 from moving away from the gas canister 40 after the outlet has been opened. For example, a number of ratchets or detents 66 may be provided on one or both of the opening pin 62 and the proximal hub 14a of the drive assembly 12 to allow the drive assembly 12 to move proximally relative to the opening pin 62 with minimal interference. However, after the drive assembly 12 is retracted and the opening pin 62 opens the outlet, the detents 66 couple or otherwise limit the movement of the opening pin 62 to the drive assembly 12 to prevent the opening pin 62 from following further distal movement of the drive assembly 12 to close the outlet (which may otherwise result in the drive assembly 12 and canister 40 moving distally away from the opening pin 62).

[0026] Alternatively, the cap 44 may be a hermetic cap that includes a septum or other weakened area (not shown) that is opened by an opener mechanism. In this alternative, the opener mechanism may include a puncture pin (not shown) configured to pierce or preferentially tear the septum. Additional information regarding usable canisters and methods of making the same may be found in U.S. Publication No. 2017 / 0258583, the entire disclosure of which is expressly incorporated herein by reference.

[0027] 4A-4C, the canister 40 can be oriented such that the outlet end 42b is proximal to the closed end 42a, with the opener mechanism 60 located proximal to the outlet end 44. Alternatively, the orientation can be reversed, with the outlet end 42b facing distally, with the opener mechanism 60 located distal to the outlet end 42b (not shown). In this alternative, the opener mechanism is coupled to the drive assembly 12, the canister 40 is substantially stationary within the housing 8, and proximal movement of the drive assembly 12 can direct an opening pin proximally to open the canister.

[0028] 1B, the drive assembly 12 includes a pair of proximal seals 32 that seal the proximal chamber 30, e.g., a first or proximal O-ring 32a mounted about the proximal hub 14a and a second or distal O-ring 32b mounted about the first region 22a of the annular wall, e.g., in a respective annular groove or recess. The O-rings 32a, 32b can slidably engage the inner wall 10a of the housing 8 to provide a fluid-tight seal that seals the proximal chamber 30 while accommodating axial movement of the drive assembly 12 within the housing 8. For example, as further described elsewhere herein, when pressurized gas is released from the canister 40, the pressurized gas passes through the first chamber 22 and the passageway 28 into the proximal chamber 30, thereby generating a distal force that advances the drive assembly 12 distally and directs the needle 78 from the distal end 8b of the housing 8 and into the skin of the subject.

[0029] To achieve the distal force, the second O-ring 32b can have a larger outer diameter than the first O-ring 32a, and the inner wall 10a of the housing 8 can include first and second regions corresponding to the diameters of the O-rings 32a, 32b. For example, as best seen in Figures 4A, 4B, and 5C, the inner wall 10a can include a first or proximal region 10a1 extending distally from the first O-ring 32a and a second or distal region 10a2 extending distally from the second O-ring 32b having a larger diameter than the first region 10a1. When the device 6 is actuated to move the drive assembly 12 distally from its initial position, the first O-ring 32a slidably engages the first region 10a1 and the second O-ring 32b slidably engages the second region 10a2.

[0030] The O-rings 32a, 32b and the proximal chamber 30 are configured to advance the drive assembly 12 distally, i.e., direct the needle 78 from the housing 8 and into the skin of the subject, as further described elsewhere herein. When pressurized gas flows into the proximal chamber 30 (immediately after being released from the canister 40), the pressure generates a net distal force that directs the drive assembly 12 distally due to the difference in diameter of the O-rings 32a, 32b. Given the difference in diameter, i.e., the second or distal O-ring 32b having a larger diameter than the first or proximal O-ring 32a, the surface area of ​​the second O-ring 32b exposed to the gas pressure is also larger than the first O-ring 32a. Given the uniform pressure from the pressurized gas acting on the opposing surface areas, the distal force acting on the second O-ring 32b will be greater than the proximal force acting on the first O-ring 32a, thereby generating a net distal force that advances the drive assembly 12 distally.

[0031] 1A and 1B, the syringe 70 generally includes a barrel 72 having a closed distal end 72a from which a needle 78 extends, and an open proximal end 72b that slidably receives a piston or stopper 74 to enclose an agent chamber 73 that contains, for example, one or more therapeutic and / or diagnostic agents in liquid or other flowable form. The proximal end 72b and the distal end 16 of the drive assembly 12 may include cooperating features to secure the syringe 70 to the drive assembly 12, for example, to couple axial movement to one another. For example, as best seen in FIG. 1B, the proximal end 72b of the barrel 72 may include one or more flanges, for example, a radial flange or a pair of opposing flanges 76, that are received within corresponding recesses in the distal end 16 of the drive assembly 12. Additionally or alternatively, drive assembly 12 may be provided with one or more detents, ridges or other features (not shown) for securing syringe 70 .

[0032] In one example, the syringe 70 may be a pre-filled syringe, e.g., formed from glass, plastic, etc., and filled with a preset amount of drug, e.g., corresponding to a patient dose. Alternatively, the drug chamber and needle may be integrated with the drive assembly, if desired (not shown). In yet another alternative, the syringe 70 (or integrated drug chamber) may include a needle-less distal port (not shown), in which case a separate needle (also not shown) may be coupled to the port immediately prior to injection or as desired, e.g., using a luer fitting, mating threads, and / or other cooperating connector.

[0033] Plunger 50, which may include an elongated rod or other member, includes a proximal end 52 slidably disposed within second chamber 26, e.g., initially immediately adjacent first chamber 20, and a distal end 54 coupled to a stopper 74. Plunger 50 is movable from an initial or retracted position (e.g., as shown in FIGS. 1B, 5A, and 5B) to a final or extended position (e.g., as shown in FIG. 7A), e.g., where distal end 54 extends from second end 16 of drive assembly 12 into drug chamber 73 of syringe 70.

[0034] The proximal end 52 of the plunger 50 is provided with a flange or other guide member 53 that slidably engages the wall of the second chamber 26. As a result, when pressurized gas enters the second chamber 26 (via the first chamber 22), the pressure creates a distal force that directs the plunger 50 distally from an initial position toward a final position, advancing the stopper 74 and delivering one or more medicaments from the medicament chamber 73 through the needle 78 and into the subject, as further described elsewhere herein.

[0035] Optionally, a syringe spacer or adapter 75 can be provided that provides an interface between, for example, the distal end 54 of the plunger 50 and the piston 74 to provide a connector therebetween and / or to ensure proper spacing so that the piston 74 advances in conjunction with the plunger 50. Thus, spacers 75 of various lengths can be provided so that syringes of various lengths can be loaded into the housing 8 while properly positioning the needle 78 adjacent the distal end 8b of the housing 8. For example, during manufacture or assembly, a syringe 70 can be selected that is inserted into the housing 8 and coupled to the distal end 16 of the drive assembly 12, for example, via an opening in the distal end 8b. Prior to loading the syringe 70, a corresponding spacer 74 can be coupled to the piston 74 or the distal end 54 of the plunger 50.

[0036] Optionally, the drive assembly 12 can include a wall or intermediate passage (not shown) between the first and second chambers 22, 26. The intermediate passage can have a relatively small diameter to provide a restrictor for shortening the pressure rise time in the second chamber 26, e.g., to enhance the initial flow of pressurized gas into the proximal chamber 30 to advance the drive assembly 12 and needle 78 before the plunger 50 begins to advance. Alternatively, a precision orifice (not shown) can be inserted between the first and second chambers 22, 26 if desired to act as a restrictor. For example, the orifice can i) slow the transient flow of gas and delay the rise in pressure applied to the plunger 50, e.g., to provide a soft start to the injection, reducing / eliminating pressure shock waves in the fluid being injected in the syringe, reducing pain to the patient as the drug injection is initiated more gradually, and / or ii) slow the steady state flow of gas and reduce other pressures applied to the plunger 50, providing a limiting effect on the flow rate of the drug being injected to the patient.

[0037] Optionally, as shown in FIG. 6C, the flange 53 at the proximal end of the plunger 50 can include one or more passages 53a extending between the proximal and distal faces 53b, 53c of the flange 53. For example, the flange 53 can include a plurality of circular or other enclosed passages 53a spaced apart from one another around the circumference of the flange 53, each extending between the proximal and distal faces 53b, 53c. Alternatively, the one or more passages can be grooves (not shown) formed in the outer surface of the flange extending between the proximal and distal faces 53b, 53c.

[0038] In this case, flange 53 may be sized and / or shaped to slidably engage the wall of second chamber 26 to, for example, allow plunger 50 to move from an initial position to an extended position, but does not require an O-ring or other seal. For example, flange 53 may be a cylindrical head having a larger outer diameter than plunger 50 and may be molded or otherwise formed with plunger 50, or may be manufactured separately and permanently attached to plunger 50.

[0039] Optional one or more passageways communicate between a region 26a of the second chamber 26 proximal to the flange 53 and a region 26b distal to the second chamber 26 surrounding the plunger 50. A cylinder seal 90 is provided within the drive assembly 12, for example, at a distal end of the second chamber 26 that may be slidably engaged with the plunger 50 to provide a fluid-tight seal with an inner wall of the second chamber 26 without substantially impeding axial movement of the plunger 50. The seal 90 may include, for example, one or more passageways 92 extending radially outward from an inner surface of the seal 90, which may communicate with one or more passageways 94 in a wall of the drive assembly 12 for delivering pressurized gas into the distal chamber 96, as further described elsewhere herein.

[0040] Optionally, plunger 50 may also include a plunger chamber 56 extending from the open proximal end 52 to the closed distal end 54 of plunger 50, as best seen, for example, in FIG. 6C. As a result, when pressurized gas enters second chamber 26, the gas can freely flow through one or more passageways 53a, to either side of second chamber 26 around plunger 50, and into plunger chamber 56, as described further below.

[0041] For example, when the canister 40 is opened and the pressurized gas is released, the initial volume that the gas must fill (including the first chamber 22 around the canister 40, the proximal chamber 30, the second chamber 26 around the plunger 50, and the optional plunger chamber 56) may result in an initial pressure drop as the gas fills the vacant volume. However, as the plunger 50 advances, the change in the volume that the gas must fill increases only minimally (e.g., the volume that the plunger 50 occupies in the second chamber 26 that is pushed out of the distal end 16 of the drive assembly 12). As a result, because the change in volume is minimized, the force exerted by the pressure on the plunger 50 remains substantially constant or only decreases slightly. Thus, the decrease in force exerted on the plunger 50 is minimized, providing a more uniform delivery rate of the medicament from the syringe 70. Additional information regarding plungers capable of reducing pressure drop is provided in co-pending U.S. application Ser. No. 17 / 965,707, the entire disclosure of which is expressly incorporated herein by reference.

[0042] Optionally, as shown in FIG. 6C, 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, as shown, the outer diameter or cross-section can be tapered between the proximal end 52 and the distal end 54 of the plunger 50. Such a taper can increase the cross-sectional area of ​​the plunger 50 as it progresses from an initial position toward a final position, thereby minimizing changes in the distal force applied to the syringe stopper due to changes in volume. This is particularly useful in applications where a constant delivery rate is desired.

[0043] It will be appreciated that any of these features associated with plunger 50 may be combined with one another or omitted, as desired.

[0044] 1B with further reference to FIGS. 6C and 7C, the drive assembly 12 includes a pair of distal seals 98, e.g., a first or distal O-ring 98a and a second or proximal O-ring 98b mounted, e.g., in respective annular grooves or recesses, around the second portion 24 of the drive assembly 12, that seal the distal chamber 96. The O-rings 98a, 98b can slidably engage the inner wall 10b of the housing 8 to provide a fluid-tight seal that seals the distal chamber 96 while accommodating axial movement of the drive assembly 12 within the housing 8. The distal seals 98 and distal chamber 96 can be configured such that when the plunger 50 reaches a final position (after injecting the subject with one or more medicaments), pressurized gas enters the distal chamber 96 and generates a proximal force that retracts the drive assembly 12 proximally and returns the needle 78 into the distal end 8b of the housing 8, as shown, e.g., in FIGS. 7A and 7B.

[0045] For example, proximal end 52 of plunger 50 includes one or more passages 52a extending radially outward from proximal end 52, e.g., distal to flange 53. As the plunger advances to a final position, one or more passages 52a align with passages 92 in cylinder seal 90, as shown, e.g., in FIGS. 7A-7C. Pressurized gas in second chamber 26 (released from canister 40 to advance plunger 50) is then free to travel from plunger chamber 56 through passages 52a, 92, 94 and into distal chamber 96, thereby generating a proximal force that retracts drive assembly 12 proximally and pulls needle 78 back into distal end 8b of housing 8.

[0046] To obtain the proximal force, the second O-ring 98b can have a larger outer diameter than the first O-ring 98a, and the inner wall 10b of the housing 8 can include first and second regions corresponding to the diameters of the O-rings 98a, 98b. For example, as best seen in FIGS. 6C and 7C, the inner wall 10b can include a first or distal region 10b1 extending proximally from the first O-ring 98a, and a second or proximal region 10b2 extending proximally from the second O-ring 98b having a larger diameter than the first region 10b1. When the drive assembly 12 moves proximally from its advanced position following delivery of one or more medicaments in the syringe 70, the first O-ring 98a slidably engages the first region 10b1, and the second O-ring 98b slidably engages the second region 10b2.

[0047] Similar to O-rings 32a, 32b and proximal chamber 30, when pressurized gas enters distal chamber 30, the pressure generates a net proximal force that leads drive assembly 12 proximally due to the difference in diameters of O-rings 98a, 98b, so distal O-rings 98a, 98b and distal chamber 96 are configured to generate a proximal force that retracts drive assembly 12 proximally due to the pressurized gas. Given the difference in diameters, i.e., proximal O-ring 98b has a larger diameter than distal O-ring 98a, the surface area of ​​second O-ring 98b is also larger than first O-ring 98a. Given the uniform pressure from the pressurized gas acting on the opposing surface areas, the proximal force acting on second O-ring 98b is greater than the distal force acting on first O-ring 98a, thereby generating a net proximal force that retracts drive assembly 12 proximally.

[0048] Additionally, O-rings 98a, 98b have a larger diameter than the diameter of proximal O-rings 32a, 32b (and distal inner wall 10b has a larger diameter than proximal inner wall 10a), such that the net proximal force generated by distal chamber 96 is greater than the net distal force generated by proximal chamber 30, resulting in a net force in the proximal direction that positively retracts drive assembly 12.

[0049] It will be appreciated that the relative diameters of the pair of proximal seals 30 and the pair of distal seals 96 can be selected to generate desired net distal and net proximal forces during corresponding stages of operation of the device 6. For example, the net distal force for initially advancing the drive assembly 12 can be selected to be relatively low to advance the needle 78 into the subject's skin at a desired rate, e.g., to minimize discomfort, while the net proximal force can be much greater, e.g., to quickly remove the needle after delivering the agent(s) in the syringe 70. Additionally, the force applied to the plunger 50 to advance the plunger 50 and stopper 74 to deliver the agent(s) can be relatively large to quickly deliver the agent(s) to minimize the overall time required to complete an injection.

[0050] Seals 32, 98 and other seals in device 6, such as cylinder seal 90, may form a sealed or contained system in which pressurized gas from canister 40 is delivered to a series of chambers with minimal leakage.

[0051] During use, the device 6 may initially be provided with a safety cap 86 attached to the distal end 8b of the housing 8, as shown, for example, in FIGS. 1A and 1B. For example, the safety cap 86 may prevent the actuation cap 80 from being guided in a proximal direction, for example by preventing the actuation cap 80 from being touched. Additionally 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 the needle shield 79 may prevent the needle 78 from being exposed from the housing 8 prior to use. Thus, just prior to making an injection, the safety cap 86 may be removed to expose the contact surface 84 of the actuation cap 80, as shown, for example, in FIG. 2.

[0052] As shown in FIGS. 3A and 3B, by placing the contact surface 84 against the subject's skin (not shown) and then pressing the device 6 against the skin, the actuation cap 80 is moved proximally to direct the drive assembly 12 proximally within the housing 8, which causes the opening pin 60 to open the outlet of the gas canister 40 and release the pressurized gas into the first chamber 22. For example, as shown, the proximal end 82 of the actuation cap 80 can include one or more detents or tabs 83 that can contact the barrel 72 of the syringe 70 and push the syringe 70, thereby directing the entire drive assembly 12 coupled to the syringe 70 (including the canister 40 carried by the drive assembly 12) proximally. As the drive assembly 12 and canister 40 move proximally, the opening pin 60 opens the outlet of the canister 40 and releases the pressurized gas into the first chamber 22 around the canister 40, as shown, for example, in FIG. 4C.

[0053] The pressurized gas may then pass through one or more passageways 28 into the proximal chamber 30 sealed by the proximal seal 32, as shown in Figure 5C, generating a distal force that may advance the entire drive assembly 12 distally to direct the needle 78 out of the distal end 8b of the housing 8 and into the subject's skin, as shown in Figures 5A and 5B, for example. If the canister 40 includes a ball closure 46, as shown in Figure 5C, for example, the feature 66 may engage the opening pin 60 to move distally with the drive assembly, thereby preventing the ball from closing the outlet, as shown in Figure 5B.

[0054] As the drive assembly 12 is advanced, one or more tabs 83 on the actuation cap 80 can be configured to deflect or otherwise allow the syringe 70 to be advanced out of the way into the proximal end 82 of the actuation cap 80, as shown, for example, in FIG. 6A, to avoid interference with directing the needle 78 out of the distal end 8b of the housing 8 and into the skin of the subject. The actuation cap 80 and / or the housing 8 can include one or more cooperating features to, for example, prevent the actuation cap 80 from moving in a distal direction as the drive assembly 12 and the syringe 70 are advanced. For example, as shown in FIG. 6B, one or more teeth or ratchets 81, 11 can be provided on an inner surface of the actuation cap 80 and the housing 8 to permit the actuation cap 80 to move in a proximal direction (e.g., during initial actuation) but subsequently prevent it from moving in a distal direction.

[0055] For example, pressing the actuation cap 80 against the subject's skin may generate a relatively small force sufficient to allow the detents 83 to push the syringe 70 and drive assembly 12 proximally during initial actuation, without interference from the teeth or ratchets 81, 11 to permit such proximal movement. However, once the pressurized gas is released and the drive assembly is advanced, a relatively large force may be generated to deflect the detents 83 on the actuation cap 80, thereby preventing the teeth or ratchets 81, 11 from moving distally or impeding the advancement of the syringe 70 to direct the needle 78 into the subject's skin.

[0056] Further, as shown in Figures 6A and 7A, pressurized gas can enter the second chamber 26 from the first chamber 22 and direct the plunger 50 distally from the initial position toward the final position, delivering one or more medicaments from the syringe 70 through the needle 78 and into the subject's body.

[0057] As shown in FIGS. 7A and 7B, when the plunger 50 reaches its final position, pressurized gas enters the distal chamber 96 sealed by the distal seal 98, i.e., through the passages 52a, 92, 94, which generates a proximal force that retracts the drive assembly 12 proximally and returns the needle 78 into the distal end 8b of the housing 8. Thus, the entire operation of the device 6 is initiated by simply pressing the actuation cap 80 against the subject's skin, and the pressurized gas communicates with the chamber to advance the needle, inject one or more medicaments, and retract the needle without further operator action. The device 6 can then be safely discarded without risk of subsequent contact with the needle 78. Optionally, the safety cap 86 and / or the needle shield 79 can be reattached to the distal end 8b of the housing 8, if desired.

[0058] 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 is to be understood, however, that the invention is not limited to the specific forms or methods disclosed, but rather, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the appended claims.

Claims

1. 1. A device for delivering one or more agents into a subject's body, comprising: an outer housing including a proximal end and a distal end; an actuation cap attached to the distal end of the housing, the actuation cap having a contact surface disposed distal to the distal end of the housing; a drive assembly slidable within the housing; a syringe at the distal end of the drive assembly, the needle of the syringe being positioned within the distal end of the housing adjacent the actuation cap; a gas canister in a first chamber in the proximal end of the drive assembly; a plunger having a proximal end within the second chamber of the drive assembly and a distal end coupled to a piston of the syringe; an opening pin adjacent to the outlet of the gas canister; the actuation cap is movable relative to the housing, and is configured such that when a contact surface of the actuation cap is pressed against the skin of the subject, the actuation cap moves proximally to direct the drive assembly proximally within the housing, causing the opening pin to open an outlet of the gas canister and release pressurized gas into the first chamber; The drive assembly includes a pair of proximal seals sealing a proximal chamber in communication with the first chamber, the proximal seals being configured such that, when pressurized gas is released, the pressurized gas generates a distal force that advances the drive assembly distally and guides the needle from the distal end of the housing and into the skin of the subject, and the pressurized gas enters the second chamber and guides the plunger distally from an initial position toward a final position to deliver one or more medicaments from the syringe through the needle and into the subject.

2. 10. The device of claim 1, the drive assembly includes a pair of distal seals that seal a distal chamber and a passageway that communicates with the second chamber when the plunger reaches a final position, the distal seals being configured such that when pressurized gas enters the distal chambers, the pressurized gas generates a proximal force that retracts the drive assembly proximally and returns the needle to the distal end of the housing.

3. 1. A device for delivering one or more agents into a subject's body, comprising: an outer housing including a proximal end and a distal end; an actuation cap attached to the distal end of the housing, the actuation cap having a contact surface disposed distal to the distal end of the housing; a drive assembly slidable within the housing; a syringe at the distal end of the drive assembly, the needle of the syringe being positioned within the distal end of the housing adjacent the actuation cap; a gas canister in a first chamber in the proximal end of the drive assembly; a plunger having a proximal end within the second chamber of the drive assembly and a distal end coupled to a piston of the syringe; an opening pin adjacent to the outlet of the gas canister; the actuation cap is movable relative to the housing, and is configured such that when a contact surface of the actuation cap is pressed against the skin of the subject, the actuation cap moves proximally to direct the drive assembly proximally within the housing, causing the opening pin to open an outlet of the gas canister and release pressurized gas into the first chamber, and the pressurized gas enters the second chamber and directs the plunger distally from an initial position toward a final position to deliver one or more medicaments from the syringe through the needle into the subject; the drive assembly includes a pair of distal seals that seal a distal chamber and a passageway that communicates with the second chamber when the plunger reaches a final position, the distal seals being configured such that when pressurized gas enters the distal chambers, the pressurized gas generates a proximal force that retracts the drive assembly proximally and returns the needle to the distal end of the housing.

4. 3. The device according to claim 1 or 2, The device, wherein the proximal seal includes first and second O-rings slidably engaging an inner wall of the housing within a proximal region of the housing, the inner wall surrounding the proximal chamber.

5. 5. The device of claim 4, the second O-ring is located distally of the first O-ring and has a larger diameter than the first O-ring, whereby pressurized gas in the proximal chamber generates a net distal force that directs the drive assembly distally.

6. 6. The device of claim 5, the first O-ring slidably engages a first region of the inner wall and the second O-ring slidably engages a second region of the inner wall, the second region having a larger diameter than the first region.

7. 4. The device according to claim 2 or 3, the distal seal includes third and fourth O-rings slidably engaging an inner wall of the housing within a distal region of the housing, the inner wall surrounding the distal chamber.

8. 8. The device of claim 7, the third O-ring is located proximally relative to the fourth O-ring and has a larger diameter than the fourth O-ring, whereby pressurized gas in the distal chamber generates a net proximal force that retracts the drive assembly proximally.

9. 9. The device of claim 8, the third O-ring slidably engages a third region of the inner wall, the fourth O-ring slidably engages a fourth region of the inner wall, the third region having a larger diameter than the fourth region.

10. 9. The device of claim 8, the third and fourth O-rings have diameters greater than a diameter of the second O-ring such that the net proximal force is greater than the net distal force.

11. 9. The device of claim 8, the third and fourth O-rings have a cross-sectional area greater than a cross-sectional area of ​​the second O-ring such that the net proximal force is greater than the net distal force.

12. The device according to any one of claims 1 to 3, The device further comprises a safety cap coupled to the distal end of the housing distal to the actuation cap to prevent the actuation cap from being guided proximally.

13. The device according to any one of claims 1 to 3, The device further comprises a safety cap removably coupled to the distal end of the housing distal to the actuation cap to prevent the needle from being exposed from the housing before the safety cap is removed.

14. The device according to any one of claims 1 to 3, the gas canister includes a ball that initially seals an outlet spaced from the opening pin, and when the drive assembly is initially retracted, the gas canister is displaced such that the opening pin pushes the ball to open the outlet and release gas within the gas canister.

15. 15. The device of claim 14, 10. A device comprising: an opening pin having one or more features configured to prevent the opening pin from moving away from the gas canister after the outlet is opened.

16. 16. The device of claim 15, The device, wherein the one or more features include a plurality of ratchets or detents on one or both of the release pin and the proximal end of the drive assembly.

17. The device according to any one of claims 1 to 3, the gas canister includes a pierceable septum initially spaced from the opening pin, and when the drive assembly is initially retracted, the gas canister is displaced such that the opening pin pierces the septum and releases gas within the gas canister.

18. 18. The device of claim 17, a septum of the gas canister oriented proximally within the first chamber and the opening pin oriented distally toward the septum.

19. The device according to any one of claims 1 to 3, The plunger includes a plunger chamber extending from an opening at a proximal end that communicates with the second chamber, and wherein pressurized gas from the gas canister entering the second chamber fills the plunger chamber.

20. The device according to any one of claims 1 to 3, a proximal end of the piston comprising a flange separating the second chamber into a proximal region and a distal region, and a proximal end of the piston comprising one or more passages configured to allow gas from the gas canister entering the second chamber to pass from the proximal region into the distal region.

21. 21. The device of claim 20, The plunger includes a plunger chamber extending from an opening at a proximal end that communicates with the second chamber, and wherein pressurized gas from the gas canister entering the second chamber fills the plunger chamber.

22. 21. The device of claim 20, A device wherein the proximal end of the plunger has a larger cross section than the distal end of the plunger.

23. 23. The device of claim 22, The device wherein the cross section of the plunger is tapered between the proximal and distal ends of the plunger.

24. The device according to any one of claims 1 to 3, The device, wherein the housing includes a window that allows observation of the piston of the syringe.

25. The device according to any one of claims 1 to 3, The device, wherein the syringe includes a barrel defining the medication chamber, the needle extending from a distal end of the syringe, and the piston being slidable within the barrel.

26. 26. The device of claim 25, The device, wherein one or both of the syringe and the drive assembly include one or more connectors for securing the syringe to a distal end of the drive assembly.

27. 26. The device of claim 25, a syringe spacer coupled to the plunger having a length corresponding to a length of the syringe coupled to the drive assembly to position the needle adjacent the distal end of the housing.

28. The device according to any one of claims 1 to 3, The device, wherein the actuation cap and housing include cooperating features for preventing distal movement of the actuation cap.

29. 29. The device of claim 28, the one or more cooperating features include one or more teeth or ratchets on one or both of the actuation cap and the interior surface of the housing, the one or more teeth or ratchets allowing the actuation cap to move proximally but preventing subsequent distal movement.

30. The device according to any one of claims 1 to 3, The device further comprising a vent for releasing excess pressurized gas from the housing when the drive assembly is retracted to return the needle to the housing.

31. The device according to any one of claims 1 to 3, The device, characterized in that the actuation cap has a proximal end that contacts the syringe, the syringe is coupled to the drive assembly, and proximal movement of the actuation cap causes the proximal end of the actuation cap to push the syringe proximally and guide the drive assembly proximally.

32. 32. The device of claim 31 , The device further comprises one or more detents or tabs at the proximal end of the actuation cap that contact the syringe to urge the syringe proximally, the one or more detents or tabs being configured to deflect out of the way of the syringe when the drive assembly is directed distally to avoid interfering with directing the needle into the subject's skin.

Images