Power assist for manual and automatic syringe injection devices

Abstract

A power-assisted injection device can administer a liquid medicament. The injection device can include a syringe, a housing, and a motive force device. The syringe can include a plunger and a barrel configured to hold the liquid medicament. The housing can include a body configured to hold the syringe. The housing can also include a latch configured to define a locked position that prevents movement of the plunger and a released position that allows movement of the plunger. The motive force device can be configured to apply an injection force to the plunger while the latch is in the released position to administer the medicament. The injection device can be configured to administer the liquid medicament upon release of the latch from the locked position at least partially via the motive force device that applies the injection force to the plunger of the syringe.

Description

[Background technology]

[0001] Subcutaneous injections are commonly used to deliver medications to patients using a variety of injection devices, such as syringes, needle-safe devices, and various auto-injectors. Examples of needle-safe devices include the UltraSafe Injection System and the UltraSafe Plus Injection System sold by Becton Dickinson.

[0002] Typical needle safety devices often require the user to remove the cap, insert the exposed needle at the injection site, and manually press the plunger with their thumb until the injection is complete. Some injectors then retract the needle and empty syringe into the body of the device. The device can then be disposed of.

[0003] Existing auto-injectors may require the user to remove the cap, place the device on the skin (with the needle hidden by the needle shield), and press down firmly. The start of delivery is triggered by pressing a button or by depressing the needle guard. The user continues to hold the device against the skin until delivery is complete. To deliver high-viscosity and / or high-volume medications, the user may be required to apply more force and / or inject for a longer time and frequency (compared to low-viscosity and / or low-volume medications). In any of these situations, the user may experience hand discomfort or fatigue. Therefore, improved injection devices are desirable. Summary of the Invention

[0004] A power-assisted injection device can administer a liquid medicament. The injection device can include a syringe, a housing, and a motive force device. The syringe can include a plunger and a barrel configured to hold the liquid medicament. The housing can include a body configured to hold the syringe. The housing can also include a latch configured to define a locked position that prevents movement of the plunger and a released position that allows movement of the plunger. The motive force device can be configured to apply an injection force to the plunger while the latch is in the released position to administer the medicament. The injection device can be configured to administer the liquid medicament upon release of the latch from the locked position at least partially via the motive force device that applies the injection force to the plunger of the syringe.

[0005] A power-assisted injection device for administering a liquid medicament may include a syringe, at least one spring, a housing, and a loading actuator. The syringe may include a plunger and a barrel configured to hold the liquid medicament. The at least one spring may be configured to apply an injection force to the plunger to administer the medicament. The housing may include a body configured to hold the syringe and a flange configured to translate relative to the housing body and configured to contact the plunger to apply the injection force to the syringe. The loading actuator may be configured to load the spring. The injection device may be configured to administer the liquid medicament upon loading of the spring.

[0006] A power-assisted injection device for administering a liquid medicament may include a syringe, a housing, a barb assembly, a plenum, and a compressed gas container. The syringe may include a barrel configured to hold the liquid medicament and a piston configured to administer the medicament. The housing may include a body configured to hold the syringe. The barb assembly may be disposed within the housing and may include a barb and a support structure configured to support the barb. The plenum may be defined at least by the housing and the piston of the syringe. The compressed gas canister may be configured to be movable relative to the barb. The gas canister may have a ready position in which the gas canister is sealed and spaced apart from the barb, and an engaged position in which the gas canister contacts the barb such that the barb penetrates a seal on the gas canister. The barb penetrating the seal on the gas canister allows gas to pressurize the plenum and apply an injection force to the piston, thereby driving the piston relative to the barrel of the syringe to administer the medicament.

[0007] A power-assisted injection device for administering a liquid medicament may include a cartridge, a housing, and an actuator. The cartridge may include a barrel configured to hold the liquid medicament. The housing may include a body configured to hold the cartridge, a first housing helical thread on an inner surface of the body defining a first pitch, a second housing helical gear thread on an inner surface of the body defining a second pitch, and a bung configured for linear motion relative to the body and configured to apply an injection force to the cartridge. The actuator may be configured to engage the first and second housing helical threads and to apply the injection force to the bung.

[0008] A power-assisted injection device for administering a liquid medicament may include a cartridge and a housing. The cartridge may include a plunger and a barrel configured to hold the liquid medicament. The housing may include a lower body, an upper body, and a coaxial pinion pair including a first pinion and a second pinion having a common pinion shaft. The upper housing body may be configured to receive a linear force. The upper housing body may include a rack configured to engage with teeth of the first pinion. The lower housing body may have a rack configured to engage with teeth of the second pinion and configured to apply an injection force to the plunger of the cartridge. A linear force applied to the upper housing body relative to the lower housing body may translate the upper housing body rack and rotate the first and second pinions, and the second pinion may transmit movement to the lower housing body rack, thereby translating the lower housing body and applying the injection force to the plunger. The pitch of the first pinion and upper body rack can be greater than the pitch of the second pinion and lower body rack, such that the housing lower body moves less than the housing upper body in response to a unit movement of the housing upper body.

[0009] A power-assisted injection device for administering a liquid medication may include a syringe, a housing, and a pulley assembly. The syringe may include a plunger and a barrel configured to hold the liquid medication. The housing may include a lower body and an upper body movable relative to the lower body. The pulley assembly may include a pulley wheel and a tether extending around the pulley wheel. The tether may have a first end and a second end, the first end coupled to the upper housing body and the second end coupled to the lower housing body. The pulley wheel may engage with the syringe plunger. Movement of the upper housing body relative to the lower housing body may generate tension in the tether, thereby generating an injection force on the plunger via the pulley wheel. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 10 is a diagram of a power-assisted injection device with dual extension springs shown in a locked, extended position. [Figure 1B] 1B is a view of the device of the embodiment of FIG. 1A showing the spring in a retracted position upon release from the locked position. [Figure 1C] 1B is a diagram of the device of the embodiment of FIG. 1A showing the needle guard deployed over the needle after actuation of the injection device and delivery of the drug. [Figure 2A] FIG. 1 is a schematic diagram of a second embodiment of a power-assisted injection device using a single spring, shown in a locked, extended position. [Figure 2B] FIG. 2B is a schematic diagram of the second embodiment device of FIG. 2A shown in an unlocked, extended position. [Figure 2C] FIG. 2C is a schematic diagram of the device of the second embodiment of FIG. 2B showing the spring in a fully contracted position upon completion of drug administration. [Figure 2D] FIG. 2D is a schematic diagram of the second embodiment device of FIG. 2C after activation of the spring-loaded needle guard over the needle. [Figure 3A] FIG. 10 is a schematic diagram of a third embodiment of a power-assisted injection device using dual springs in compression, shown in a locked, retracted position. [Figure 3B] FIG. 3B is a schematic diagram of the device of the third embodiment of FIG. 3A shown in an unlocked, retracted position. [Figure 3C] FIG. 3C is a schematic diagram of the device of the third embodiment of FIG. 3B showing the spring in a fully extended position upon completion of drug administration. [Figure 3D] FIG. 2D is a schematic diagram of the third embodiment device of FIG. 2C after activation of the spring-loaded needle guard over the needle. [Figure 4A] FIG. 10 is a perspective view of the injection device of the fourth embodiment before actuation of the plunger. [Figure 4B] FIG. 1 is an enlarged cut-say view showing the gas canister and plunger in the ready position. [Figure 4C]FIG. 10 is a schematic diagram of a fourth embodiment of a power-assisted injection device using a gas canister, shown in the ready position (unpierced) prior to use. [Figure 4D] 4B is a schematic diagram of the fourth embodiment of the device of FIG. 4A showing the gas canister actuated by piercing and the piston in a fully actuated position upon completion of administration of the drug. [Figure 5A] FIG. 10 is a schematic diagram of a fifth embodiment of a power-assisted injection device using a magnet, shown in a spaced, ready position with the plunger fully extended. [Figure 5B] 5B is a schematic diagram of the fifth embodiment device of FIG. 5A showing the attractive force between the magnet and the partially actuated plunger. [Figure 5C] FIG. 5C is a schematic diagram of the fifth embodiment of FIG. 5B showing the magnets in contact and the plunger in a fully actuated position upon completion of administration of the drug. [Figure 6A] FIG. 10 is a partially transparent perspective view of a sixth embodiment of a power-assisted injection device including a pair of springs and a spring reset device, showing the lever of the reset device in the down position and the spring in a pre-loaded, ready position. [Figure 6B] 6B is a perspective view of the device of the sixth embodiment of FIG. 6A, opposite the view of FIG. 6A. [Figure 6C] 6B is a partially transparent perspective view of the sixth embodiment of FIG. 6A showing the lever in an up or retracted position and the device in a ready position. [Figure 7A] FIG. 6D is a schematic diagram of the device of the sixth embodiment, showing the ready position shown in FIG. 6C. [Figure 7B] FIG. 10 is a schematic diagram of the device of the sixth embodiment showing the spring in a fully extended position upon completion of drug administration. [Figure 7C] FIG. 6B is a schematic diagram of the device of the sixth embodiment, showing the lever in the lowered position shown in FIG. 6A. [Figure 8A]FIG. 10 is a schematic diagram of a seventh embodiment of a power-assisted injection device using dual springs in a compressed state, shown in a locked, retracted position, including a surface to allow resetting of the device. [Figure 8B] 8B is a schematic diagram of the device of the third embodiment of FIG. 8A showing the spring in a fully extended position upon completion of drug administration. [Figure 9A] FIG. 10 is a partial cross-sectional view of an eighth embodiment of a power-assisted injection device using a single spring, shown in a locked, extended position with the spring in tension and the reset device in an up position. [Figure 9B] FIG. 9B is a partial cross-sectional side view of the eighth embodiment of the device of FIG. 9A. [Figure 9C] FIG. 9C is a partial cross-sectional side view of the eighth embodiment of the device of FIG. 9B showing the spring in a fully contracted position upon completion of administration of the drug, with the reset device not yet engaged. [Figure 9D] 9D is a partial cross-sectional side view of the eighth embodiment of the device of FIG. 9C after actuation of the lever of the reset device has caused the spring to return to its extended, ready position. [Figure 9E] 9B shows the base portion of the eighth embodiment device of FIG. 9A removed from the actuator to show engagement of the reusable base with the syringe. [Figure 10A] FIG. 13 is a perspective view of a ninth embodiment of a power-assisted injection device that uses a helical geared plunger to provide a mechanical advantage to the user, with the plunger shown in the extended, ready position. [Figure 10B] FIG. 10B is a schematic cross-sectional view of the device of the ninth embodiment of FIG. 10A. [Figure 10C] FIG. 10B is a schematic cross-sectional view of the device of the ninth embodiment in the ready position shown in FIG. 10A. [Figure 10D] FIG. 10B is a schematic cross-sectional view of the device of the ninth embodiment in the ready position shown in FIG. 10A. [Figure 10E] FIG. 13 is a schematic cross-sectional view of a device of a ninth embodiment showing the plunger in an actuated position upon completion of administration of a drug (not shown). [Figure 10F] FIG. 10F is a perspective view of the device of the ninth embodiment of FIG. 10E. [Figure 10G] FIG. 10F is an enlarged cross-sectional view of the device of FIG. 10E. [Figure 10H] FIG. 10G is an enlarged cross-sectional view of the device of FIG. 10G showing the needle guard deployed over the needle after actuation of the injection device and delivery of the drug. [Figure 10I] FIG. 10H is an enlarged perspective cross-sectional view of the device shown in FIG. [Figure 10J] FIG. 10H is an enlarged perspective cutaway view of the device of FIG. 10H showing the needle guard deployed over the needle after actuation of the injection device and delivery of the drug. [Figure 11A] FIG. 13 is a perspective view of a tenth embodiment of a power-assisted injection device using a dual rack and pinion. [Figure 11B] 11B is a schematic diagram of the tenth embodiment of the device of FIG. 11A showing the plunger in an extended, ready, non-actuated position. [Figure 11C] FIG. 11C is a cross-sectional view of the device of FIG. 11B showing the plunger in an extended, ready, unactuated position. [Figure 11D] 11C is a perspective partial cross-sectional view of the embodiment of FIG. 11B showing the plunger in an extended, ready, non-actuated position. [Figure 11E] 11E is a perspective partial cross-sectional view of the device of the embodiment of FIG. 11D showing the plunger in a partially actuated position. [Figure 11F] 11D is a perspective partial cross-sectional view of the device of the embodiment of FIG. 11D showing the plunger in an actuated position upon completion of administration of the drug. [Figure 11G] 11B is a schematic diagram of the device of the embodiment of FIG. 11A showing the plunger in an actuated position upon completion of administration of the drug. [Figure 11H] FIG. 11B is a perspective view of the embodiment device of FIG. 11A showing the plunger in an actuated position upon completion of drug administration. [Figure 11I]FIG. 11B is a perspective exploded view of a portion of the device of the ninth embodiment shown in FIG. 11A showing that the cap can be removed to allow for syringe replacement. [Figure 12A] FIG. 11 is a schematic diagram of an eleventh embodiment of a power-assisted injection device using a pulley system for mechanical advantage, showing the plunger in an extended, ready position. [Figure 12B] 12B is a schematic diagram of the device of the embodiment of FIG. 12A showing the plunger in a fully actuated position upon completion of administration of the drug. [Figure 12C] 12B illustrates the principle of mechanical advantage employed by the device of the embodiment of FIG. 12A. [Figure 13A] FIG. 12 is a schematic diagram of a twelfth embodiment of a power-assisted injection device in an extended, ready position, using a pair of springs in series to allow the force applied to the syringe plunger to be varied during actuation. [Figure 13B] FIG. 13B is an enlarged schematic view of the injection device of FIG. 13A. [Figure 13C] FIG. 13B is a schematic diagram of the injection device of FIG. 13A showing the first spring in an extended position for placing the syringe in a partially actuated position. [Figure 13D] FIG. 13D is an enlarged schematic view of the device of FIG. 13C. [Figure 13E] FIG. 13B is a schematic diagram of the injection device of FIG. 13A showing the second spring in an extended position to place the syringe in its fully actuated position upon completion of administration of the medication. [Figure 13F] FIG. 13F is an enlarged schematic view of the device of FIG. 13E. DETAILED DESCRIPTION OF THE INVENTION

[0011] The injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) can be a power-assisted injection device that administers a medication from a syringe. The medication can be a viscous liquid medication. The viscous liquid medication can have a viscosity of about 10 centipoise to about 375 cp at 20°C. The injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) can be adapted to receive a syringe 102 (FIG. 1A). The syringe 102 may be adapted to allow a user to manually administer an injection without using an injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300). The syringe 102 may be configured to deliver a dose of medication without the aid of an injection device. The syringe 102 may be coupled to an injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) to reduce the user's effort in administering the injection. The syringe 102 may include a barrel 122 adapted to hold a liquid medication. A flange 103 may extend radially outward from the barrel 122. The flange 103 can engage the housing to prevent axial movement of the syringe 102 during injection. The flange 103 can be disposed at the proximal end of the syringe 102.

[0012] The medication can be delivered from the barrel 122 through the exit port 124 to the patient. In some examples, the exit port 124 is a needle. In other examples, the exit port 124 is a cannula. In other examples, the exit port 124 is an opening in the barrel such that an injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) delivers a needleless injection. The exit port 124 can be in fluid communication with the barrel 122 such that liquid medication can pass from the barrel 122 through the exit port 124 and be delivered to the patient. The exit port 124 can be located at the distal end of the syringe 102. A plunger 126 can be movably received within the barrel 122. The plunger 126 can provide a fluid seal with the barrel 122. The plunger 126 may be movable relative to the barrel 122 such that movement of the plunger 126 towards the exit port 124 forces the medication out of the exit port 124 .

[0013] The injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) may include a needle guard. The needle guard may be adapted to extend beyond the distal end of the needle after injection to prevent accidental needle sticks. The needle guard may be a passive mechanism that automatically extends without additional action from the user. The distal end of the needle guard 121 may include an opening through which the ejection port 124 or at least a portion of the syringe 102 can extend when the needle guard 121 is not extended. The needle guard 121 may be fixed relative to the housing 104. For example, the needle guard 121 may be at least one of rotationally and axially fixed relative to the housing 104.

[0014] The piston 128 can be operatively associated with the plunger 126. Operatively associated can mean that the piston 128 is in contact with the plunger 126 during injection. Movement of the piston 128 can cause movement of the plunger 126 relative to the barrel 122. In some embodiments, the piston 128 and the plunger 126 are separate elements. In other embodiments, the piston 128 and the plunger 126 are a unitary structure. The piston 128 can be axially spaced apart from the plunger 126 when the injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) is in a pre-injection configuration. The piston 128 can move axially to engage the plunger 126 when the injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) transitions from a pre-injection configuration to an injection configuration. In other embodiments, the piston 128 engages the plunger 126 when the injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) is in the pre-injection configuration. In some embodiments, the injection device 100 is reusable by changing the syringe 102 such that the piston 128 remains coupled to the housing 104 when the syringe 102 is changed. In other embodiments, the piston 128 is associated with the syringe 102 such that the piston 128 is decoupled from the housing 104 when the syringe 102 is replaced.

[0015] 1A-1C, there is shown an injection device 100. The injection device 100 may be movable from a pre-injection configuration (FIG. 1A) to an injection configuration (FIG. 1B). The injection device 100 may be movable from the injection configuration to a post-injection configuration (FIG. 1C).

[0016] The injection device 100 may include a housing 104. The housing 104 may be manually engageable by a user. The housing 104 may include a proximal end 110 and a distal end 112 opposite the proximal end 110 along a central axis A1. The housing 104 may include a housing body 118 defined by an outer wall. The housing 104 may be sized and shaped to receive the syringe 102. A needle guard 121 may be coupled to the housing body 118. The needle guard 121 may be fixed in position relative to the housing body 118. The needle guard 121 may define a recess that receives at least a portion of the syringe 102. The housing body 118 may define a recess that receives at least a portion of the syringe 102 such that the syringe 102 is enclosed by the housing 104 and the needle guard 121. The needle guard 121 may be removably coupled to the housing body 118. Syringe 102 may be fixed relative to housing 104 during injection, or may be movable relative to housing 104 after medication has been dispensed from syringe 102, as described in more detail below.

[0017] The injection device 100 may include a flange 130 adapted to move the piston 128 relative to the housing body 118. The flange 130 may be movable relative to the housing body 118 along the axis A1. The flange 130 may engage and move the piston 128 relative to the housing body 118. In some embodiments, the flange 130 and the piston 128 are separate elements. In other embodiments, the flange 130 and the piston 128 are a unitary structure. The flange 130 may be axially spaced from the piston 128 when the injection device 100 is in the pre-injection configuration. The flange 130 may move to engage the piston 128 when the injection device 100 transitions from the pre-injection configuration to the injection configuration. In other embodiments, the flange 130 is in contact with the piston 128 when the injection device 100 is in the pre-injection configuration.

[0018] A user can apply a force to flange 130 to move flange 130 relative to housing body 118. A distal end of housing body 118 may include finger flange 108 such that a user can engage finger flange 130 with two fingers while engaging and applying a force to flange 108 with their thumb. Finger flange 108 may include an opening configured to receive needle guard 121. Needle guard 121 may be removably received within the opening defined by finger flange 108. Housing body 118 may include opening 139 to allow a user to move flange 130 within housing body 118.

[0019] The housing body 118 may include a latch 132 adapted to define a locked position that prevents movement of the piston 128 and an released position that allows movement of the piston 128. The latch 132 may be any suitable latch capable of defining a locked position and an released position. In one example, the latch 132 may include a protrusion that engages the underside of the flange 130 when the latch 132 is in the locked position, thereby holding the flange 130 in the locked position until released. At least one of the latch 132 and the flange 130 may be flexible such that, upon application of sufficient force, one of the flange 130 and the latch 132 flexes and disengages from the other of the flange 130 and the latch 132. A user may apply an initiating force to the flange 130 to move the latch 132 from the locked position to the released position. The initiating force may be less than the injection force applied by the motive force device 136. The initiating force may be between about 15 Newtons and about 40 Newtons.

[0020] The injection device 100 may include a prime mover device 136 adapted to apply an injection force to the plunger 126 to administer the medication while the latch 132 is in the released position. The injection force is separate and distinct from an initiation force. A user may apply an initiation force, and the prime mover device 136 may apply an injection force. The initiation force may be applied over an initiation time. The injection force may be applied over an injection time. The initiation time may be about 1 second. The injection time may be about 1 second to about 10 seconds, about 10 seconds to about 30 seconds, about 30 seconds to about 45 seconds, about 45 seconds to about 1 minute, or at least about 1 minute. The initiation force may be applied to the flange 130. The injection force may be applied to the plunger 126. In some embodiments, the prime mover device 136 applies sufficient injection force to the plunger 126 to complete the injection without the user manually applying any force to the flange 130 after the latch 132 is in the released position. The injection device 100 may be adapted to administer a liquid medicament upon release of the latch 132 from an at least partially locked position via a driving force device 136 that applies an injection force to the plunger 126 of the syringe 102. The driving force device 136 may apply the injection force to the plunger 126 via the piston 128. The injection force may be between about 10 Newtons and about 25 Newtons, between about 25 Newtons and about 50 Newtons, between about 50 Newtons and about 75 Newtons, or between about 75 Newtons and about 100 Newtons. In some examples, the injection device 100 includes a 27-gauge needle for delivering a liquid having a viscosity of about 1 centipoise, and the injection force is about 14 Newtons for a 3-second injection. In other examples, the injection device 100 includes a 27-gauge needle for delivering a liquid having a viscosity of about 60 centipoise, and the injection force is about 50 Newtons for a 10-second injection.

[0021] In some embodiments, the motive force device 136 applies the injection force without requiring additional force from the user. In other embodiments, the injection force of the motive force device 136 is insufficient to move the plunger 126, but the latch 132 releases without any external force applied by the user. Thus, the user must apply a force to the flange 130 in addition to the force from the motive force device 136 to perform the injection. The motive force device 136 may be coupled to the flange 130. Alternatively, the motive force device 136 may be coupled to the piston 128.

[0022] The motive force device 136 can transition from an expanded state to a relaxed state when the injection device 100 moves from the pre-fire configuration to the firing configuration. The motive force device 136 can be a biasing element. The motive force device 136 can be at least one spring engaged with the housing body 118. The at least one spring can be a pair of springs engaged with the housing body 118. The housing body 118 can include a base 116 proximate an upper portion of the barrel 122. The at least one spring of the motive force device 136 can be in tension between the base 116 and the flange 130. Alternatively, the motive force device 136 can be a gas-fired piston.

[0023] The injection device may include a syringe holder 141 (shown in FIG. 1C ). The syringe holder 141 may be coupled to the barrel 122 of the syringe 102. When coupled to the syringe holder 141, the barrel 122 may be fixed in position relative to the syringe holder 141, at least axially. The needle guard 121 may be configured to move axially relative to the syringe holder 141 to transition between an initial position ( FIGS. 1A and 1B ) in which the distal end of the exit port 124 extends out of the needle guard 121 and a retracted position ( FIG. 1C ) in which the distal end of the exit port 124 is retracted within the needle guard 121. In some examples, the syringe holder 141 and the needle guard 121 are part of the UltraSafe Plus injection system sold by Becton Dickinson and Company.

[0024] The return force device 134 may be adapted to move the syringe 102 from the injection position (FIG. 1B) to the post-injection position (FIG. 1C). The return force device 134 may be a biasing element (e.g., a spring). The return force device 134 may exert opposing forces on the needle guard 121 and the syringe holder 141 to move the syringe holder 141 (and thus the syringe 102) proximally relative to the housing 104 (including the needle guard 121). The exit port 124 may be present in the needle guard 121 when the syringe 102 is in the post-injection position.

[0025] Flange 130 may include a first portion 138 and a second portion 140 (FIG. 1C). First portion 138 may be removably coupled to second portion 140. Motivation device 136 may be coupled to second portion 140 such that motive device 136 moves first portion 138 and second portion 140 from a pre-injection position to an injection position. A latch (not shown) may couple first portion 138 to second portion 140. First portion 138 and second portion 140 may move together from a pre-injection position to an injection position.

[0026] A disengaging member 142 may be coupled to the housing body 118 and adapted to disengage the first portion 138 from the second portion 140. The disengaging member 142 may include a protrusion 144 adapted to engage the syringe holder 141 to retain the needle guard 121 in the initial position (FIGS. 1A and 1B). At least one of the first portion 138 and the second portion 140 may disengage the disengaging member 142 from the syringe holder 141 to allow the return force device 134 to move the syringe 102 from the initial position to the retracted position (FIG. 1C).

[0027] At least a portion of the injection device 100 may be reusable. For example, a user may move the second portion 140 of the flange 130 to engage the latch 132. The user may replace the syringe 102 with a new syringe and reuse the injection device 100. The syringe 102 may be detached from the injection device 100 by decoupling the syringe barrel 122 from the syringe holder 141. A new syringe 102 may be coupled to the injection device 100 so that the injection device 100 may be used again.

[0028] 2A-2D illustrate another embodiment of an injection device 200. The injection device 200 may include a housing 210 adapted to receive the syringe 102. The injection device 200 may include a plunger 228 adapted to apply an injection force to the syringe 102. A motive force device 236 may be coupled to the plunger 228 for moving the plunger 228 relative to the housing 210. Alternatively, the motive force device 236 may be coupled to a flange 202 coupled to the plunger 228. The motive force device 236 may be a spring coaxial with the plunger 228. The spring may be in tension between a base of the housing 210 and the flange 202. The motive force device 236 may define a recess with at least a portion of the plunger 228 therein.

[0029] The flange 202 may include a first portion 204 and a second portion 206. The first portion 204 may be movable relative to the second portion 206. The second portion 206 may be fixed to a plunger 228. The second portion 206 and the plunger 228 may be a unitary structure. As described below, movement of the first portion 204 relative to the second portion 206 can initiate an injection. The first portion 204 may include a first portion central axis extending along a maximum length of the first portion 204, and the second portion 206 may include a second portion central axis extending along a maximum length of the second portion 206. The first portion central axis may be coaxial with the second portion central axis.

[0030] The housing 210 may include a latch 208 adapted to define a locked position that prevents movement of the plunger 228 and a released position that allows movement of the plunger 228. The latch 208 may be engageable with the flange 202. For example, the latch 208 may engage with the second portion 206. In some embodiments, the latch 208 may be a flexible arm that moves from a locked position ( FIG. 2A ) to a released position ( FIG. 2B ). The flange 202 may be movable relative to the housing 210 when the latch 208 is in the released position.

[0031] The latch 208 may include a protrusion 212 (FIG. 2C) engageable with the underside of the flange 202 to prevent axial movement of the flange 202 in a distal direction when the latch 208 is in the locked position. The latch 208 may hold the flange 202 in the locked position until released. The latch 208 may include a ramp 214 engageable with the first portion 204. The first portion 204 may be movable relative to the second portion 206 while the second portion 206 is engaged with the protrusion 212. For example, the first portion 204 may be translatable along axis A2 relative to the second portion 206 (FIG. 2A). Movement of the first portion 204 relative to the second portion 206 may move the latch 208 from the locked position to the released position. In some examples, a release force may be required to move the latch 208 from the locked position to the released position. The release force may be between about 15 N and about 40 N. First portion 204 can engage ramped surface 214 such that protrusion 212 moves out of engagement with second portion 206. In some embodiments, latch 208 includes a cantilevered arm that bends radially outward, away from the central axis of housing 210, when first portion 204 engages ramped surface 214. Latch 208 can move into contact with an inner surface of housing 210 when latch 208 bends from the locked position to the released position.

[0032] Latch 208 can be a sidewall that extends continuously circumferentially around an opening sized to receive flange 202. Alternatively, latch 208 can be two or more sidewalls spaced apart from one another around the circumference that define an opening for receiving flange 202.

[0033] A first end of motive force device 236 may be coupled to flange 202. A second end of motive force device 236 may be coupled to housing 210. For example, motive force device 236 may be coupled to second portion 206 of flange 202 and a distal portion of housing 210. motive force device 236 may be in tension between flange 202 and the distal portion of housing 210.

[0034] The injection device (e.g., 200, 300, 400, 500, 600, 800, 900, 1100, or 1200) may include a needle guard 220 that is movable relative to the housing to cover the needle after injection. The needle guard 220 may be movable relative to at least one of the housing 210 and the syringe 102 from an injection position to a post-injection position. The needle guard 220 may encase at least a portion of the syringe 102 in the post-injection position. The needle guard 220 may extend distally beyond the distal end of the ejection port 124 when the needle guard is in the post-injection position. The ejection port 124 may extend distally from the distal end of the needle guard 220 when the needle guard 220 is in the injection position.

[0035] The needle guard 220 can be at least temporarily secured to the housing 210 prior to injection. The needle guard 220 can include an arm 222 that engages with a lower wall 224 of the housing 210. The lower wall 224 can include an opening such that the arm 222 extends from a first side of the lower wall 224 to a second side of the lower wall 224 opposite the first side along axis A2. The arm 222 can include a detent engageable with the lower wall 224 to at least temporarily maintain the position of the needle guard 220 relative to the housing 210. The arm 222 can be movable from an engaged position to a disengaged position. The arm 222 can be a cantilever extending proximally from the proximal end of the body of the needle guard 220. The detent of the arm 222 can be engaged with the lower wall 224 in the engaged position and disengaged from the lower wall 224 in the disengaged position. The arm 222 can be flexible from the engaged position to the disengaged position. Needle guard 220 may be movable relative to housing 210 when arm 222 is in the disengaged position.

[0036] The flange 202 can be adapted to move the arm 222 from an engaged position to a disengaged position. The flange 202 can include a disengaging member 226 that moves the arm 222 as the flange 202 moves axially toward the lower wall 224. For example, one of the disengaging member 226 and the arm 222 can include a ramped surface engageable with the other of the disengaging member 226 and the arm 222 such that axial translation of the flange 202 causes the arm 222 to move radially to the disengaged position. The needle guard 220 can move from the injection position toward the post-injection position when the arm 222 is in the disengaged position.

[0037] The lower housing 238 may be coupled to the housing 210. The lower housing 238 may include a sidewall sized and shaped to movably receive the needle guard 220. The lower housing 238 may include a ledge 240 adapted to engage the arm 222 when the needle guard 220 is in the post-injection position. The injection device 200 may include a syringe holder 241 (shown in FIG. 2D ). The syringe holder 241 may be coupled to the barrel 122 of the syringe 102. When coupled to the syringe holder 241, the barrel 122 may be fixed in position relative to the syringe holder 241 in at least an axial direction. The syringe holder 241 may be fixed in position relative to the housing 210. Needle guard 220 may be configured to move axially relative to syringe holder 241 to transition between an injection position (FIGS. 2A, 2B, and 2C) in which the distal end of exit port 124 extends out of needle guard 220, and a post-injection position (FIG. 2D) in which the distal end of exit port 124 is retracted within needle guard 220. In some examples, syringe holder 241 and needle guard 220 are part of the UltraSafe Plus injection system sold by Becton Dickinson.

[0038] The biasing element 232 can provide a force to move the needle guard 220 from the injection position to the post-injection position. The biasing element 232 can include a first portion that exerts a force against an underside of the lower wall 224 or against the syringe holder 241. The biasing element 232 can include a second portion that exerts a force against the needle guard 220. The biasing element 232 can be adapted to expand when the arms 222 are in the disengaged position. For example, the biasing element 232 can be a spring that is compressed when the needle guard 220 is in the injection position, such that the needle guard 220 expands when it is no longer constrained by the arms 222.

[0039] The injection device 200 may be reusable. A user can disengage the syringe holder 241 and the needle guard 220 from the lower housing 238 and remove the syringe 102. For example, the user can apply a radially inward force to disengage the arm 222 from the lower housing 238 and pull the needle guard 220 away from the lower housing 238. The user can then move the plunger 228 proximally until the second portion 206 engages the latch 208. The user can then insert a new syringe 102 into the needle guard 220. The needle guard 220 can then be recoupled to the housing 210 and moved proximally until the arm 222 engages the housing 210.

[0040] 3A-3D illustrate another embodiment of an injection device 300. The injection device 300 may be similar to the injection device 200. However, the motive force device 336 of the injection device 300 may differ from the motive force device 236 of the injection device 200. For example, the motive force device 336 may include at least one spring in a compressed state between the housing base 312 and the housing flange 338 while the latch 208 is in the locked position. The motive force device 336 may be adapted to move the flange 202 relative to the housing 210 when the latch 208 is in the released position.

[0041] The housing 310 may include a base 312 adjacent the top of the housing body 318. The housing flange 338 may be a bar, plate, or rod adapted to contact and move the flange 202 for injection. The housing flange 338 may have a width similar to the interior width of the housing 310 to maintain alignment of the housing flange 338 with the housing 310 when the housing flange 338 is moved to the post-injection position. Maintaining alignment of the housing flange 338 may help ensure smooth and complete delivery of the dose of medication. The housing flange 338 may include a central axis extending along the greatest length of the housing flange 338. The central axis of the housing flange may be perpendicular to the central axis A3 of the injection device 300.

[0042] Movement of the first portion 204 of the flange 202 relative to the second portion 206 can initiate an injection by moving the latch 208 to a released position, as discussed above. The motive force device 336 can exert a force against the housing flange 338. The housing flange 338 can apply an injection force to the flange 202 in response to the force applied by the motive force device 336 such that the flange 202 moves relative to the housing 310. In some examples, the injection device 300 is configured to couple to an existing injection system. One injection system contemplated for use with the injection device 300 is the UltraSafe Plus injection system sold by Becton, Dickinson and Company.

[0043] 4A-4D illustrate another embodiment of an injection device 400. The injection device 400 may include a housing 410 having a housing body 418 adapted to hold the syringe 102. The housing 410 may include a power source for moving the syringe plunger 126 relative to the barrel 122. The power source may be a compressed gas canister 436. The gas in the canister may be hexafluoroacetone (HFA), liquefied petroleum gas, helium, nitrogen, oxygen, or VaporSoft, manufactured by Recipharm AB, headquartered in Stockholm, Sweden. Actuation of the canister 436 may release compressed gas to move the syringe plunger 126.

[0044] The canister 436 may include a seal 404 that can be penetrated or displaced to allow compressed gas to exit the canister. The seal 404 may be positioned at a distal end of the canister 436. In some embodiments, the seal 404 may be a penetrable or frangible end of the canister 436. In other embodiments, the seal 404 may be a plug that engages with an open sidewall of the canister 436, thereby sealing the canister.

[0045] Barb assembly 438 may be adapted to pierce or displace seal 404 to allow gas to exit canister 436. Barb assembly 438 may include a barb 440 adapted to pierce seal 404. Barb 440 may have a pointed tip to facilitate piercing seal 404. Alternatively, barb 440 may have a blunt or rounded end that pushes seal 404 out of engagement with the open sidewall of canister 436. Barb 440 may include an opening extending therethrough to allow gas from canister 436 to flow through barb 440.

[0046] The barb assembly 438 may include a support structure 442 adapted to support the barb 440. The support structure 442 can fix the position of the barb assembly relative to the canister 436 during injection. The support structure 442 can be operatively associated with the flange 103 of the syringe 102 to axially fix the position of the barb 440 relative to the syringe 102 during injection. The barb 440 can have a height, measured along the central axis A4, that is greater than the height of the support structure 442, such that gas from the canister 436 can flow through the barb 440 from a first side of the support structure 442 to a second side opposite the first side. In some embodiments, the support structure 442 can sealingly engage the flange 103 of the syringe to reduce or prevent gas leakage at the interface between the flange 103 and the support structure 442.

[0047] The housing 410 can define a channel 444 for receiving the syringe flange 103 and the support structure 442. The housing 410 can include a partition 446 separating the channel 444 from an opening 448. The partition 446 can be a protrusion extending inward from the housing body 418. The partition 446 can include an opening such that at least one of the barb 440 and a portion of the canister 436 extends through the opening. The support structure 442 can be slightly compressed between the flange 103 and the partition 446 to prevent unintentional damage to the flange 103 or firing of the injection device 400 prior to intended use. In other embodiments, the partition 446 can be positioned between the support structure 442 and the flange 103. In yet other embodiments, the housing 410 does not include the partition 446 such that the canister 436 and the barb assembly 438 are disposed within the opening 448. The injection device 400 may include a plenum 420 between the piston 128 and the flange 103 of the syringe 102. Gas from the canister 436 may fill the plenum 420 when the injection device 400 is activated. At least a portion of the support structure 442 may be positioned within the plenum 420.

[0048] In some embodiments, the support structure 442 may be fixed relative to the housing 410. In other embodiments, the support structure 442 is movable relative to the housing 410. For example, the support structure 442 may be coupled to the canister 436, such that when the canister 436 moves relative to the housing 410, the canister can move the support structure 442. The divider 446 may stop the axial movement of the support structure 442 when the support structure is movable relative to the housing 410. The canister 436 may continue to move axially when the support structure 442 stops moving, such that there is relative movement between the canister 436 and the support structure 442. The barb 440 may be fixed to the support structure 442 such that when the support structure 442 is fixed relative to the canister 436, the barb 440 is fixed relative to the canister 436, and when the support structure 442 is movable relative to the canister 436, the barb 440 is movable relative to the canister 436.

[0049] The canister 432 can be in slidable contact with the housing body 418, which defines an opening 448. The opening 448 can have a width W1 in a plane perpendicular to the central axis A4. The width W1 can be greater than the width W2 of the channel 444. There can be an interference fit between the canister 436 and the sidewalls of the opening 448 to prevent unintentional movement of the canister 436 prior to use.

[0050] The canister 436 may be movable relative to the housing 410 between a ready position (FIG. 4C) and an engaged position (FIG. 4D). The canister 436 may be spaced apart from the barb 440 in the ready position (e.g., spaced apart axially along axis A4). The canister 436 may be sealed in the ready position. The canister 436 may move relative to the barb 440 as the canister 436 moves from the ready position to the engaged position. The canister 436 may slide within the opening 448 as the canister 436 moves from the ready position to the engaged position. The barb 440 may pierce a seal on the canister 436 as the canister 436 moves to the engaged position. When the barb 440 pierces the seal and pressurizes a plenum, applying an injection force to the piston 128, gas may exit the canister 436, thereby driving the piston 128 against the syringe barrel to administer the medication.

[0051] The canister 436 may include an activator 452 ( FIG. 4B ) engageable by a user to move the canister 436 from the ready position to the engaged position. The activator 452 may include a first end 454 operably associated with the canister 436. In some embodiments, the first end 454 is coupled to the canister 436 when the canister 436 is in the ready position. In other embodiments, the first end 454 is axially spaced apart from the canister 436 along the central axis A4 when the canister 436 is in the ready position. The first end 454 may be moved into contact with the canister 436 when the activator 452 is moved relative to the housing 410 by a user. The activator may be disposed within an opening in a proximal portion of the housing 410.

[0052] The distal end of the housing body 418 may include a finger flange 408 that is engageable by a user during use of the injection device 400. For example, a user can engage the finger flange 408 with two fingers while engaging the activator 452 with their thumb. The user can apply force to the activator 452 to move the canister 436 relative to the housing 410. In some examples, the injection device 400 is configured to couple to an existing injection system. One injection system contemplated for use with the injection device 400 is the UltraSafe Plus injection system sold by Becton Dickinson.

[0053] 5A-5C illustrate another embodiment of an injection device 500. The injection device 500 may include a housing 510 that receives at least a portion of the syringe 102. The housing 510 may be a syringe holder. A needle guard 522 may be coupled to the housing 510. At least one of the housing 510 and the needle guard 522 may be coupled to the barrel 122 of the syringe 102. When coupled to the housing 510, the barrel 122 may be fixed in position relative to the housing 510 at least axially. The needle guard 522 may be configured to move axially relative to the housing 510 to transition between an injection position ( FIGS. 5B and 5C ) in which the distal end of the exhaust port 124 extends out of the needle guard 522 and a post-injection position (not shown) in which the distal end of the exhaust port 124 is retracted within the needle guard 522. In some examples, the housing 510 and needle guard 522 are part of the UltraSafe Plus injection system sold by Becton Dickinson.

[0054] The injection device 500 may include a plunger 528 operatively associated with the piston 128 of the syringe 102 to dispense the medication from the syringe 102. For example, the plunger 528 may move the piston 128 relative to the barrel 122 of the syringe 102 to dispense the medication from the outlet port 124.

[0055] The injection device 500 may include a motive force device 536 adapted to apply an injection force to the plunger 528 to administer the medication. The motive force device 536 may include a pair of magnetic components. The first magnetic component 538 and the second magnetic component 540 are each magnets oriented to attract the other of the first magnetic component 538 and the second magnetic component 540. Alternatively, one of the first magnetic component 538 and the second magnetic component 540 may be a magnet, and the other of the first magnetic component 538 and the second magnetic component 540 may be an ferrous structure for attracting the magnet. The first magnetic component 538 may be coupled to the housing 510 proximal to the barrel 122 of the syringe 102. The second magnetic component 540 may be coupled to the plunger 528 at or near the plunger flange 530.

[0056] The distal end of the housing body 518 may include a flange 508 engageable by a user to activate the injection device 500. For example, a user may engage the flange 508 with two fingers while engaging the piston flange 530 with their thumb. The user may initiate an injection by applying a force to the piston flange 530 to move the plunger 528 relative to the housing 510. The force applied by the motive force device 536 may increase as the distance between the first magnetic component 538 and the second magnetic component 540 decreases. The motive force device 536 may provide a force of about 14 N to about 100 N. In some embodiments, the motive force device 536 exerts at least some force before the plunger 528 begins to move. In other embodiments, the motive force device 536 applies the injection force only when the plunger 528 has moved a selected distance. For example, the selected distance can be about 10%, about 20%, about 30%, about 40%, or about 50% of the travel distance of the plunger 528. The first magnetic component 538 and the second magnetic component 540 can be spaced apart from each other until administration of the medication is complete. In some embodiments, the first magnetic component 538 contacts the second magnetic component 540 when the injection device 500 is in the post-injection configuration. In other embodiments, the first magnetic component 538 is spaced apart from the second magnetic component 540 when the injection device 500 is in the post-injection configuration.

[0057] 6A-6C illustrate another embodiment of an injection device 600 that may include a force device to facilitate injection and a load actuator adapted to apply a load to the force device. The injection device 600 may include a housing 610 adapted to hold a syringe 102. The housing 610 may include a housing body 618, a lower wall 612, and an upper wall 622. The lower wall 612 may include a channel 613 for receiving a portion of the syringe 102. The channel 613 may extend through a surface of the lower wall 612 in a transverse direction T that is perpendicular to both the longitudinal direction L and the axial direction A, which may be parallel to the central axis A6, such that the syringe 102 may be loaded within the channel. The channel 613 may extend in the transverse direction T from a first side of the lower wall 612 to a second side of the lower wall 612 opposite the first side. The channel 613 can extend through the lower wall such that the syringe 102 can be loaded along the lateral direction T from a first side or a second side of the lower wall 612. The lower wall 612 can include a groove to secure the syringe 102 in place.

[0058] The injection device may include a plunger 605 adapted to apply an injection force to the piston 128 to dispense the medicament from the syringe 102. A flange 604 may be coupled to the plunger 605. The flange 604 may be operatively associated with the plunger 605 such that the flange 604 contacts the plunger 605 to move the plunger 605 relative to the housing body 618. For example, the flange 604 may move the plunger 605 along an axis A6 relative to the housing body 618. The flange 604 may include a first portion 606 and a second portion 608. The first portion 606 may be movable relative to the second portion 608. For example, the first portion 606 may be translatable along the axis A6 relative to the second portion 608.

[0059] The housing body 618, the lower wall 612, and the upper wall 622 can define a recess for receiving a force device. The housing 610 can be adapted to receive a biasing element 636. The biasing element 636 can be at least one spring. The biasing element 636 can provide an injection force of approximately 14 N to approximately 100 N. The biasing element 636 can be adapted to apply the injection force to the piston 128. For example, the biasing element 636 can apply the injection force to the flange 604, thereby applying the injection force to the piston 128. The housing body 618 can include a first receiving area 614 and a second receiving area 616 adapted to receive the first and second biasing elements, respectively. The first receiving area 614 can be spaced apart from the second receiving area in the longitudinal direction L. The flange 604 can extend at least partially into the channels 620 of the first receiving area 614 and the second receiving area 616, respectively. Alternatively, the housing body 618 can be a single element that receives each of the first and second biasing elements, or a single biasing element.

[0060] Second portion 608 of flange 604 can extend into channel 620 such that biasing element 636 is in contact with second portion 608 during injection. Biasing element 636 can be compressed between second portion 608 and housing 610. For example, when biasing element 636 is in the ready position, the first biasing element can be compressed between second portion 608 and top wall 622 of first receiving area 614, and the second biasing element can be compressed between the second portion and top wall 622 of second receiving area 616.

[0061] The housing body 618 may include a latch 632 adapted to define a locked position that prevents movement of the plunger 605 and a released position that allows movement of the plunger 605. The latch 632 may have a protrusion that engages with the underside of the second portion 608 of the flange 604 when the latch 632 is in the locked position, thereby holding the flange 604 in the locked position until released. At least one of the latch 632 and the first portion 606 of the flange 604 may be flexible to allow the first portion 606 to translate along axis A6 from a first side of the latch 632 to a second side of the latch 632 opposite the first side. For example, the latch 632 may be a flexible arm cantilevered from at least one of the first receiving area 614 and the second receiving area 616. The latch 632 may include a protrusion 638 engageable by the first portion 606. As first portion 606 moves relative to second portion 608, first portion 606 contacts protrusion 638 and moves latch 632 out of engagement with second portion 608, thereby moving latch 632 from the locked position to the released position. Biasing element 636 can move plunger 605 relative to housing 610 when latch 632 is in the released position. Second portion 608 of flange 604 can slide within channel 620 from the ready position to the firing position as plunger 605 moves relative to housing 610.

[0062] 6A-6C and 7A-7C, the injection device 600 may include a loading actuator 640 adapted to load the biasing element 636. The injection device 600 may be adapted to administer a liquid medicament upon loading of the biasing element 636. The loading actuator 640 may include a linkage assembly 642 adapted to move the at least one biasing element 636 from a firing position (FIG. 7B) to an armed position (FIGS. 6A and 7C). The linkage assembly 642 may include a lever arm 644 coupled to the housing body 618. The lever arm 644 may be pivotable about a pivot 646 fixed to the housing body 618. The lever arm 644 may be configured to rotate about the pivot 646. The pivot 646 may be fixed to an outer surface of the housing body 618. Alternatively, the pivot 646 may be fixed to the lower wall 612 of the housing 610. In another alternative, the pivot 646 may be coupled to an interior of at least one of the first receiving area 614 and the second receiving area 616. The lever arm 644 may include a first end 643, a second end 645 opposite the first end 643, and a length measured from the first end to the second end. The length may be the longest dimension of the lever arm 644. The pivot 646 may be positioned between the first end 643 and the second end 645.

[0063] Linkage assembly 642 may include at least one linkage arm 648 pivotally coupled to lever arm 644. Linkage arm 648 may be pivotally coupled to an end of lever arm 644 so that application of a force to lever arm 644 transmits a load force upward (i.e., in axial direction A) through linkage arm 648 to compress biasing element 636. Linkage arm 658 may be pivotally coupled to lever arm 644 at connection point 650. Connection point 650 may be positioned between second end 645 and pivot 646. Pivot 646 may be positioned between first end 643 and connection point 650. Second end 645 may be positioned within housing body 618. Although only one linkage arm is shown, it is understood that any number of desired linkage arms may be coupled together between the lever arm and platform 652.

[0064] The linkage assembly 642 may include a platform 652 adapted to engage and move the flange 604 when the biasing element 636 is compressed. For example, the platform 652 may move the flange 604 along axis A6. The platform 652 may move the flange 604 along axis A6 in response to rotational movement of the lever arm 644. Although only one linkage arm is shown, it will be understood that any number of desired linkage arms may be coupled together between the lever arm 644 and the platform 652. The lever arm 644 may be in a first position ( FIG. 7A ) when the injection device 600 is in the ready position. The platform 652 may be in a lowest position when the lever arm 644 is in the first position. The space between the platform 652 and the flange 604 may be a maximum distance along axis A6 when the lever arm 644 is in the first position. The flange 604 can move toward the platform 652 as the biasing element 636 expands and the injection device 600 dispenses a dose of medication. In some embodiments, the flange 604 moves into contact with the platform 652 as the biasing element 636 expands. In other embodiments, the flange 604 remains spaced apart from the platform 652 even when the biasing element 636 is fully extended within the housing 610. The lever arm 644 can rotate about the pivot 646 from a first position to a second position ( FIG. 7C ). The platform 652 can contact the flange 604 when the lever arm 644 is pivoted from the first position to the second position. The biasing element 636 can be in its most compressed state when the lever arm 644 is in the second position. The lever arm 644 can then be rotated back to the first position (FIG. 7A), thus moving the platform 652 away from the flange 604 and preparing the injection device to dispense a dose of medication.

[0065] Linkage assembly 642 may include a pair of linkage arms 648 each positioned within one of first receiving area 614 and second receiving area 616. In some embodiments, biasing element 636 is a pair of springs engaged with opposite ends of flange 604, such that application of force to lever arm 644 transfers a load force upward through linkage arms 648, compressing the springs.

[0066] 8A-8B illustrate another embodiment of injection device 800. Injection device 800 may be similar to injection device 600, except that injection device 800 does not include a linkage assembly. Instead, flange 604 may be manually moved relative to housing 610 from a first position (FIG. 8A) to a second position (FIG. 8B). For example, a user may apply force to second portion 608 to move flange 604 relative to housing 610. Alternatively, injection device 800 may be a single-use device such that flange 604 cannot return to the first position.

[0067] 9A-9E illustrate another embodiment of an injection device 900. The injection device 900 may be a power-assisted injection device for administering a liquid medication. The injection device 900 may include a housing 910 having a housing body 918 that receives at least a portion of the syringe 102. The injection device 900 may include a plunger 926 operatively associated with the piston 128 of the syringe 102 to dispense the medication from the syringe 102. For example, the plunger 926 can move the piston 128 relative to the barrel 122 of the syringe 102 to dispense the medication from the outlet port 124.

[0068] The base flange 940 can be coupled to a distal portion of the housing 910. In some embodiments, the base flange 940 is removably coupled to the housing 910. In other embodiments, the base flange 940 is fixed to the housing 910. The base flange 940 can be adapted to engage with the syringe 102. The base flange 940 can include a channel 942 such that at least a portion of the syringe 102 can be loaded within the channel 942 in a transverse direction T that is perpendicular to each of the longitudinal direction L and the axial direction A. In some embodiments, the syringe 102 can be coupled to the base flange 940 before the base flange 940 is fixed to the housing 910. A rim 944 can be coupled to a body 946 of the base flange 940. The rim 944 can protrude from a proximal surface of the base flange 940. The rim 944 can include a sidewall 948 extending around at least a portion of the channel 942. The rim 944 can include a top wall 950, such that the top wall 950, the side wall 948, and the body 946 define a receiving area for the syringe flange 103. The top wall 950 can extend from a surface of the side wall 948 facing the channel 942. The body 946 can be positioned on a first side of the syringe flange 103, and the top wall 950 can be positioned on a second side of the syringe flange 103 opposite the first side along the axial direction A. The rim 944 can be sized and dimensioned to mate with the housing body 918. A distal end of the housing body 918 can engage a proximal surface of the body 946. The base flange 940 can be coupled to the housing body 918 by threading, a snap fit, adhesive, or welding.

[0069] The injection device 900 may include a biasing element 936 that moves the plunger 926 relative to the housing 910 to expel the medicament from the syringe 102. The biasing element 936 may be a spring. The biasing element 936 may be a spring disposed coaxially around the plunger 926. The flange 902 may be coupled to the plunger 926. The flange 902 may extend radially outward beyond the outer periphery of the plunger 926. The biasing element 936 may be coupled to the flange 902 and the distal end of the housing 910. The biasing element 936 may be a spring in tension such that the spring pulls the flange 902 toward the distal end of the housing 910.

[0070] The flange 902 can resemble the flange 202 in that the flange 902 includes a first portion 904 and a second portion 906 similar to the first portion 204 and the second portion 206. The first portion 904 can include one or more legs 908 that extend through an opening in the second portion 906. The first portion 904 can be at least partially nested within the second portion 906. The first portion 904 can be movable relative to the second portion 906. For example, the first portion 904 can be movable in an axial direction A relative to the second portion 906.

[0071] The housing 910 may include a latch 912 movable between a locked configuration, in which movement of the flange 902 is prevented, and an unlocked configuration, in which movement of the flange 902 is permitted. The latch 912 may be a cantilever within an opening in the housing body 918. The latch 912 may include a protrusion extending into a central opening in the housing body 918. The first protrusion 907 ( FIG. 9C ) may engage with the second portion 906 and prevent movement (e.g., axial movement) of the flange 902 relative to the housing 910 when the latch 912 is in the locked configuration. The first portion 904 may engage with the second protrusion 909 when the first portion 904 moves relative to the second portion 906 to transition the latch 912 from the locked configuration to the unlocked configuration. The latch 912 may flex outward so that the first protrusion disengages from the second portion 906, thereby allowing the plunger 926 to move relative to the housing body 918. The first protrusion 907 and the second protrusion 909 may each be positioned within a recess defined by the housing body 918 .

[0072] The injection device 900 may include a loading actuator 941 adapted to load the biasing element 936. The injection device 900 may be adapted to administer a liquid medicament upon loading of the biasing element 936. The loading actuator 941 may be similar to the loading actuator 640. The loading actuator 941 may include a linkage assembly 962 adapted to move the at least one biasing element 936 from a firing configuration ( FIG. 9C ) to an armed configuration ( FIG. 9B ). The linkage assembly 962 may be adapted to transmit an axial force to the biasing element 936 in response to rotational movement of the linkage assembly 962.

[0073] The linkage assembly 962 may include at least one linkage arm 966 coupled to a lever arm 964. The linkage arm 966 may be coupled to an end of the lever arm 964 such that application of a force to the lever arm 964 transfers a load force through the linkage arm 966 (i.e., in the axial direction A) to compress the biasing element 936. The linkage arm 966 may be fixed to the lever arm 964. The linkage arm 966 may be rotatably fixed to the lever arm 964. The linkage arm 966 and the lever arm 964 may be monolithic elements. The linkage arm 966 may extend through an opening 911 in the housing body 918 such that the lever arm 964 can be engaged by a user to move the biasing element 936 within the housing 910. Although only one linkage arm is shown, it is understood that the link assembly 962 may include any number of linkage arms desired.

[0074] The linkage arm 966 may include a first end and a second end opposite the first end along a central axis of the linkage arm 966. The first end of the linkage arm 966 may be coupled to the lever arm 964. The second end of the linkage arm 966 may be pivotally coupled to the flange 902. The second end of the linkage arm 966 may be removably coupled to the flange 902. The lever arm 964 may include a first end and a second end opposite the first end along the central axis of the lever arm. The central axis of the linkage arm may be transverse to the central axis of the lever arm.

[0075] In some embodiments, a second end of the linkage arm 966 is coupled to the flange 902. In other embodiments, a platform (not shown) is coupled to the linkage assembly 962 to move the flange 902 along the axial direction A. The platform can be similar to the platform 652. The flange 604 can move along the axial direction A in response to rotational movement of the lever arm 964. The lever arm 644 can pivot about a pivot 914. The lever arm 644 can be fixed to the linkage arm 966 such that both the lever arm 964 and the linkage arm 966 pivot about the pivot 914. The pivot 914 can be an axis. The pivot 914 can be fixed to the housing 910. The pivot 914 can be located on a first side of the housing 910, and the channel 942 can extend through an outer surface of the base flange 940 on a second side of the housing 910 opposite the first side. The flange 902 can move along an axial direction A from a ready position to a fired position. The ready position can be proximal to the fired position. The pivot 914 can be positioned axially between the ready and fired positions. The pivot 914 can be positioned on an outer surface of the housing 910 and can be positioned along an axis generally parallel to the central axis of the housing 910 between the ready and fired positions of the flange 902.

[0076] The lever arm 964 can be in a first position ( FIGS. 9A and 9B ) when the injection device 900 is in the ready configuration. The second end of the lever arm 964 can be at its lowest position when the lever arm 964 is in the first position. The space between the second end of the lever arm 964 and the flange 902 can be at its greatest distance along the axial direction A when the lever arm 964 is in the first position. The flange 902 can move toward the second end of the lever arm 964 when the biasing element 936 expands and the injection device 900 dispenses a dose of the medication. In some embodiments, the flange 902 moves into contact with the second end of the lever arm 964 when the biasing element 936 expands. In other embodiments, the flange 902 remains spaced apart from the second end of the lever arm 964 when the lever arm 964 is in the first position and the biasing element 936 is fully extended within the housing 9010.

[0077] The lever arm 964 can be rotated from a first position to a second position (FIG. 9D). The lever arm 964 can contact the flange 902 when the lever arm 964 is pivoted from the first position to the second position. The lever arm 964 can move the flange 902 when the lever arm 964 is pivoted from the first position to the second position. The biasing element 936 can be in its most compressed state when the lever arm 964 is in the second position. The lever arm 964 can then be rotated back to the first position, and the injection device is ready to dispense a dose of medication.

[0078] 10A-10J illustrate another embodiment of an injection device 1000. The injection device 1000 may be a power-assisted injection device for administering a liquid medicament. The injection device 1000 may be adapted to provide a mechanical advantage such that the injection force applied to the medicament in the cartridge is greater than the force applied by the user. The injection device 1000 may include a cartridge 1002 having a barrel adapted to hold the liquid medicament. The cartridge 1002 may include a needle in fluid communication with the barrel, whereby the medicament is dispensed from the barrel through the needle to the injection site. The cartridge 1002 may be a syringe 102.

[0079] The injection device 1000 may include a housing 1010 having a housing body 1018 adapted to hold the cartridge 1002. The housing body 1018 may include a finger flange 1008 similar to the flange 130. The housing body 1018 may include an inner surface and an outer surface opposite the inner surface. The housing body 1018 may define an internal recess. The housing body 1018 has a first end and a central axis A. 10 and a second end spaced from the first end along a central axis A. 10 The transverse direction T may be perpendicular to both the longitudinal direction and the longitudinal direction L.

[0080] The housing body 1018 can include a first thread 1020 configured to engage the actuator 1024. The first thread 1020 can be on an interior surface of the housing body 1018. The first thread 1020 can be a helical thread. The first thread 1020 can be positioned within a proximal portion of the housing body 1018. In some embodiments, the first thread 1020 extends continuously circumferentially around the interior surface of the housing body 1018 through at least one revolution. In other embodiments, the first thread 1020 extends less than one revolution.

[0081] The housing body 1018 may include a second thread 1022 (FIG. 10D). The second thread 1022 may be configured to engage the actuator 1024. The second thread 1022 may be a helical thread. The first thread 1020 may have a first thread pitch, and the second thread 1022 may have a second thread pitch. The first thread pitch may be different from the second thread pitch. The first thread pitch may be different from the second thread pitch to provide a mechanical advantage to a force applied to the actuator 1024 by a user. The second thread 1022 may be positioned within a distal portion of the housing body 1018. In some embodiments, the second thread 1022 extends continuously circumferentially around the inner surface of the housing body 1018 through at least one revolution. In other embodiments, the second thread 1022 extends less than one revolution.

[0082] The actuator 1024 may be movable relative to the housing body 1018. The actuator 1024 may be movable longitudinally relative to the housing body 1018. The actuator 1024 moves longitudinally due to the threaded engagement between the first thread 1020 and the actuator 1024, causing the actuator 1024 to rotate about axis A. 10 In some embodiments, the actuator 1024 can be engaged with the first sled 1020 and the second sled 1022 simultaneously. In other embodiments, the actuator 1024 engages the first sled 1020 and the second sled 1022 sequentially.

[0083] The actuator 1024 may include a first member 1028 and a second member 1030. The first member 1028 may be movable relative to the second member 1030. The first member 1028 may include a recess configured to receive at least a portion of the second member 1030. The second member 1030 may be movable relative to the first member 1028 along the longitudinal axis L. The second member 1030 may be movable toward the distal end of the injection device 1000 during an injection sequence.

[0084] In some examples, the first member 1028 may include a first member thread 1034. The first member thread 1034 may be an external thread. In other examples, the outer surface of the first member 1028 may include a worm gear. The first member 1028 may include a first member body 1032 having a first member thread 1034 configured to engage with the first thread 1020. The first member thread 1034 may be positioned on the outer surface of the first member body 1032. The first member thread 1034 may be recessed into the outer surface of the first member body 1032. The first thread 1020 of the housing body 1018 extends from the inner surface of the housing body 1018 along the central axis A. 10 The outer thread 1034 may be a helical thread.

[0085] The second member 1030 may include a second member body 1036 having second member threads 1038 configured to engage with the second threads 1022. The second member threads 1038 may be positioned on an outer surface of the second member body 1036. In some embodiments, the second member threads 1038 extend along the longitudinal length of the second member body 1036. In other embodiments, the second member threads 1038 extend less than the entire length of the second member body 1036. The second member 1030 may have a cylindrical shape. The second member 1030 and the first member 1028 may be rotationally constrained relative to one another with respect to the housing body 1018. In some embodiments, the outer surface of the second member body 1036 may be radially spaced from the inner surface of the first member body 1032. In other embodiments, the outer surface of the second member body 1036 contacts the inner surface of the first member body 1032 .

[0086] The shaft 1040 may be secured to the first member body 1032. The shaft 1040 may be longitudinally coaxial with the first member body 1032. The shaft 1040 may extend distally from a proximal portion of the first member body 1032. The second member 1030 may include a recess 1042 adapted to receive the shaft 1040. Rotation of one of the first member 1028 and the second member 1030 may transmit torque to the other of the first member 1028 and the second member 1030. For example, the shaft 1040 and the recess 1042 may have a non-circular cross-sectional shape when viewed along a plane perpendicular to the axis A1 such that rotation of one of the first member 1028 and the second member 1030 transmits torque to the other of the first member 1028 and the second member 1030. Linear motion of the first member 1028 can cause rotation of the first member 1028 via the first thread 1020. Rotation of the first member 1028 can transmit rotation to the second member 1030 via the shaft 1040 and the recess 1042. Rotation of the second member 1030 can cause linear motion of the second member 1030 relative to the housing body 1018. The second member thread 1038 can have a thread pitch different from the pitch of the first member thread 1034. The pitch of the first member thread 1034 can be greater than the pitch of the second member thread 1038, such that axial translation of the second member 1030 is less than translation of the first member 1028. The second member 1030 and the first member 1028 can rotate at the same rotational speed, while the first member 1028 translates axially faster than the second member 1030.

[0087] The actuator 1024 can rotate when a user applies a linear force to the actuator 1024. A user can apply a linear force to a cap 1026 coupled to the actuator 1024. The cap 1026 can be rotatably coupled to the actuator 1024. The cap 1026 can remain rotationally fixed relative to the housing body 1018 when the actuator 1024 translates axially relative to the housing body 1018. The cap 1026 can remain rotationally fixed relative to the housing body 1018 when the actuator 1024 rotates relative to the housing body 1018.

[0088] The injection device 1000 may include a bung 1044 adapted to apply an injection force to the cartridge 1002. The bung 1044 may be coupled to the actuator 1024. The bung 1044 may be coupled to the second member 1030. The bung 1044 may be coupled to a distal end of the second member 1030. The bung 1044 may form a fluid-tight seal with the cartridge 1002. In other embodiments, the bung 1044 may push against the piston 128 of the syringe 102. The bung 1044 may apply an injection force to dispense the medicament from the cartridge 1002 when the actuator 1024 moves relative to the housing body 1018. In some embodiments, the bung 1044 is rotatably coupled to the second member 1030, such that the bung 1044 is rotationally fixed relative to the cartridge 1002 when the second member 1030 rotates. In other embodiments, the bung 1044 is rotatably fixed to the second member 1030. The second member 1030 can have a maximum length in a longitudinal or transverse direction such that at least a portion of the second member 1030 can enter the barrel of the cartridge 1002 to dispense the medicament (FIG. 10H). In other embodiments, the bung 1044 includes a stem coupled to the second member 1030 that has a longitudinal length sufficient to dispense a dose of the medicament from the cartridge 1002 without the second member 1030 entering the barrel of the cartridge 1002.

[0089] The injection device 1000 may include a needle guard 1046. The needle guard 1046 may extend distally beyond the distal end of the needle to prevent accidental needle sticks. The needle guard 1046 may be fixed relative to the housing body 1018 before injection. The needle guard 1046 may be fixed relative to the housing body 1018 after injection. The needle guard 1046 may be movable relative to the housing body 1018 after the medicament is dispensed from the cartridge 1002. A needle guard biasing element 1048 may apply a force to the needle guard 1046 to move the needle guard 1046 relative to the housing body 1018.

[0090] The collar 1050 may be adapted to secure the cartridge 1002 relative to the housing body 1018. The collar 1050 may be positioned between the housing body 1018 and the needle guard 1046. The collar 1050 may include a central opening, with the cartridge 1002 disposed within the central opening. The needle guard 1046 may be at least temporarily engaged with one of the collar 1050 and the housing body 1018. The needle guard 1046 may include a needle guard arm 1052 that engages with a rim 1054 of the housing body 1018. For example, the needle guard arm 1052 may include a protrusion 1053 (FIG. 10G) that engages with the rim 1054 when the needle guard 1046 is in the retracted position. At least one of the housing body 1018 and the needle guard 1046 may include a lock. The needle guard 1046 may engage the collar 1050 (FIG. 10H) to lock the needle guard in the extended position.

[0091] The actuator 1024 can disengage the needle guard arm 1052 from the rim 1054. One of the first member 1028 and the arm 1052 can include a ramp such that axial movement of the first member 1028 relative to the needle guard arm 1052 causes radial movement of the needle guard arm 1052. The needle guard arm 1052 can disengage from the rim 1054 as the needle guard arm 1052 moves radially to allow the needle guard 1046 to move to an extended position relative to the housing body 1018. The needle guard biasing element 1048 can maintain the needle guard in the extended position.

[0092] The needle guard 1046 can extend distally beyond the distal end of the needle when the needle guard 1046 is in the extended position. A portion of the actuator 1024 can be observable from outside the injection device 1000 when the needle guard 1046 is in the extended position. For example, a portion of the second member 1030 can be observable from outside the injection device 1000 when the needle guard 1046 is in the extended position after an injection. This can provide a visual indication to the user that the injection is complete and the injection device 1000 is in the locked configuration.

[0093] 11A-11I illustrate another embodiment of an injection device 1100. The injection device 1100 may be a power-assisted injection device for administering a liquid medicament. The injection device 1100 may be adapted to provide a mechanical advantage such that the injection force applied to the medicament in the cartridge is greater than the force applied by the user. The injection device 1100 may be adapted to receive a cartridge 1102 having a barrel adapted to hold a liquid medicament. The cartridge 1102 may include a plunger 1104 and a needle in fluid communication with the barrel, such that movement of the plunger 1104 relative to the cartridge 1102 dispenses the medicament from the barrel, through the needle, and to the injection site. The cartridge 1102 may be a syringe 102. The cartridge 1102 may be fixed relative to a housing 1110. The cartridge 1102 may be longitudinally fixed relative to the housing 1110.

[0094] The injection device 1100 may include a housing 1110 adapted to hold the cartridge 1102. The housing 1110 has a first end and a central axis A. 11 and a second end spaced from the first end along a central axis A. 11 The transverse direction T may be perpendicular to both the longitudinal direction and the longitudinal direction L.

[0095] The housing 1110 may include an upper body 1112 and a lower body 1114. The upper body 1112 and the lower body may be movable relative to one another. The housing 1110 may include a shell 1108. The upper body 1112 may be movable relative to the shell 1108. The lower body 1114 may be movable relative to the shell 1108. The upper body 1112 and the lower body 1114 may be movable relative to the shell 1108. The upper body 1112 and the lower body 1114 may be movable in a longitudinal axis direction L relative to the shell 1108. The finger flange 1106 may extend from the shell 1108.

[0096] One of the upper body 1112 and the lower body 1114 can be telescopically nested within the other of the upper body 1112 and the lower body 1114. A pinion assembly 1116 can be coupled to at least one of the upper body 1112 and the lower body 1114. The pinion assembly 1116 can include a pinion pair coupled to a shaft 1122. The pinion pair can include a first pinion gear 1118 and a second pinion gear 1120. The first pinion gear 1118 and the second pinion gear 1120 can be coaxial. The first pinion gear 1118 and the second pinion gear 1120 can each be adapted to rotate about a central axis of the shaft 1122. The first pinion gear 1118 and the second pinion gear 1120 can be coupled to the same shaft 1122. The pinion assembly 1116 may be longitudinally and axially fixed relative to the housing 1110. The shaft 1122 may be rotatable relative to the housing 1110. The shaft 1122 may be axially fixed relative to the housing 1110. The shaft 1122 may be coupled to the shell 1108.

[0097] The upper body 1112 can be adapted to engage with a first pinion gear 1118. The upper body 1112 can include an upper rack 1124 adapted to engage with teeth of the first pinion gear 1118. The upper rack 1124 and the first pinion gear 1118 can have a first gear pitch.

[0098] The lower body 1114 can be adapted to engage with the second pinion gear 1120. The lower body 1114 can include a lower rack 1126 adapted to engage with teeth of the second pinion gear 1120. The lower rack 1126 and the second pinion gear 1120 can have a second gear pitch. The first gear pitch can be different from the second gear pitch. The first gear pitch can be larger than the second gear pitch to provide a mechanical advantage when moving the lower body 1114 relative to the housing 1110. In some embodiments, the lower body 1114 moves 0.5 millimeters in response to 1 millimeter of movement of the upper body 1112 relative to the housing 1110.

[0099] An injection force can be applied to the upper body 1112. For example, a user can manually apply an axial force to the proximal end 1115 of the upper body 1112 with a thumb or finger. The upper body 1112 can include an end wall 1128 adapted to be engaged by a user to apply an axial force to the upper body 1112. One or more beams 1130 can extend from the end wall 1128. The beams 1130 can be cantilevered. The beams 1130 can extend along a central axis in the longitudinal direction L from a first end to a second end opposite the first end. The first end of the beams 1130 can be coupled to the end wall 1128. The second end of the beams 1130 can be a free end. A space 1129 can separate the beams 1130 from one another. The beams 1130 can be circumferentially spaced apart from one another. At least one beam 1130 can include the upper rack 1124. The upper rack 1124 can be formed on a single beam or on opposing beams such that the upper rack 1124 engages opposing ends of the first pinion gear 1118. The shaft 1122 can be positioned in at least one of the spaces 1129 between the beams 1130.

[0100] The housing 1110 may include guides for at least partially maintaining alignment of the beams 1130 relative to one another. In some embodiments, the guides may be protrusions that extend from the inner surface of the shell 1108 into the spaces 1129 between the beams. In other embodiments, the guides are recesses in the sidewalls of the housing 1110 that receive the beams 1130.

[0101] The lower body 1114 can be adapted to apply an injection force to the plunger 1104. The lower body 1114 can include an end wall 1132 operably associated with the plunger 1104 such that the lower body 1114 applies the injection force to the plunger 1104. For example, the plunger 1104 can be coupled to the end wall 1132. In some embodiments, the plunger 1104 and the lower body 1114 are a unitary structure. In other embodiments, the plunger 1104 and the lower body 1114 are separate elements operably associated with each other. One or more lower body beams 1134 can extend from the end wall 1132. The lower body beams 1134 can be cantilevered. The lower body beams 1134 can include a first end and a second end spaced apart from the first end along a central axis of the lower body beam. The first end of the lower body beam 1134 can be coupled to the end wall 1132 of the lower body. The second ends of the lower body beams 1134 can be free ends. Spaces 1136 can separate the lower body beams 1134 from one another. The lower body beams 1134 can be spaced apart from one another around the periphery of the lower body 1114. A halo can connect the second ends of the lower body beams 1134 to one another.

[0102] At least one lower body beam 1134 may include a lower rack 1126. The shaft 1122 may be disposed in at least one of the spaces 1136 between the lower body beams 1134. The first pinion gear 1118 may be located in at least one of the spaces 1136. The outer surface of the lower body 1114 may be spaced laterally from the inner surface of the upper body 1112.

[0103] The distal end 1140 of the lower body beam 1134 can be positioned distally beyond the distal end 1142 of the upper body beam 1130 when the injection device 1100 is in the ready configuration (FIG. 11D). The distal end 1140 of the lower body beam 1134 can be aligned with the distal end 1142 of the upper body beam 1130 along the longitudinal axis L at a moment during an injection (FIG. 11E). The distal end 1140 of the lower body beam 1134 can be positioned proximal to the distal end 1142 of the upper body beam 1130 when the injection device 1100 is in the fired configuration (FIG. 11F). At least one of the upper body 1112 and the shell 1108 can include a lockout mechanism. The lockout mechanism may be a protrusion on one of the upper body 1112 and the shell 1108 that is received in a recess on the other of the upper body 1112 and the shell 1108 to lock the injection device in a firing configuration.

[0104] The tip 1138 can be engaged with the housing 1110. The tip 1138 can be removably coupled to the housing 1110. The tip 1138 can be coupled to a distal end of the housing 1110. The tip 1138 can be coupled to the shell 1108 of the housing 1110. The tip 1138 can be configured to engage with the cartridge 1102. The tip 1138 can include an extension 1144 adapted to receive the cartridge 1102. An end face of the extension 1144 can be adapted to engage with a flange 1103 on the cartridge 1102. The extension 1144 can be positioned within the housing 1110 when the tip 1138 is coupled to the housing 1110. The cartridge 1102 can be coupled to the tip 1138 before the tip 1138 is coupled to the housing 1110. The tip 1138 may include one or more tip beams 1146. The beams 1146 may be cantilevered. The beams 1146 may extend along a central axis in the longitudinal direction L from a first end to a second end opposite the first end. The first ends of the beams 1146 may be coupled to the end wall 1138. The second ends of the beams 1146 may be free ends. Spaces 1129 may separate the beams 1146 from one another. The beams 1146 may be circumferentially spaced apart from one another. The beams 1146 may be aligned with the beams 1130 around the inner periphery of the shell 1108. The beams 1134 of the lower body 1114 may fit into the spaces between the beams 1146.

[0105] The injection device 1100 may be reusable. For example, the tip 1138 can be removed from the housing 1110 after an injection, a new cartridge 1102 can be loaded onto the tip 1138, and the tip 1138 can be recoupled to the housing 1110. A user can grasp the upper body 1112 and apply a reload force to return the injection device to the ready configuration. The reload force can be in a longitudinal direction opposite the direction of the injection force. Alternatively, a user can apply a reload force to the plunger 1104 when the tip 1138 is detached from the housing 1110 to move the upper body 1112 and lower body 1114 to a pre-injection configuration.

[0106] 12A-12B illustrate another embodiment of an injection device 1200. The injection device 1200 may be a power-assisted injection device for administering a liquid medicament. The injection device 1200 may be adapted to provide a mechanical advantage such that the injection force applied to the medicament in the cartridge is greater than the force applied by the user. The injection device 1200 may include a housing 1210 adapted to receive the syringe 102. The housing 1210 has a first end and a central axis A. 12 and a second end spaced from the first end along a central axis A. 12 may extend in a longitudinal direction L. The longitudinal direction LA may be perpendicular to the longitudinal direction L. The transverse direction T may be perpendicular to each of the longitudinal direction LA and the longitudinal direction L. The housing may include a finger flange 1208 engageable by a user during injection.

[0107] The housing 1210 may include an upper body 1212 and a lower body 1214. The upper body 1212 may be movable relative to the lower body 1214. The upper body 1212 may be longitudinally translatable relative to the lower body 1214. One of the upper body 1212 and the lower body 1214 may be telescopically nested within the other of the upper body 1212 and the lower body 1214. In some examples, the upper body 1212 extends from a proximal end of the lower body 1214 when the injection device 1200 is in a post-injection configuration. A tether 1216 may be coupled to the upper body 1212 and the lower body 1214. The tether 1216 may be a rope, chain, cable, wire, string, or belt. The tether 1216 may include a first end coupled to the upper body 1212 and a second end coupled to the lower body 1214. A tether 1216 may be coupled to a distal end of the upper body 1212. The tether 1216 may be coupled to a distal end of the lower body 1214. The distal end of the upper body 1212 may engage with the distal end of the lower body 1214 when the injection device 1200 is in a post-injection configuration (FIG. 12B).

[0108] The plunger 1204 can be movable relative to the syringe 102. The plunger 1204 is adapted to dispense a liquid medicament from the barrel of the syringe 102 when the plunger 1204 moves relative to the syringe 102. The plunger 1204 can include a pulley assembly 1218. The pulley assembly 1218 can include a pulley wheel. The tether 1216 can be engaged with the pulley wheel. The pulley assembly 1218 can be positioned proximal to a distal portion of each of the upper body 1212 and the lower body 1214. The plunger 1204 can be movable relative to each of the upper body 1212 and the lower body 1214.

[0109] The upper body 1212 can move relative to the lower body 1214 in response to the application of a force to the upper body 1212. For example, a user can engage the finger flange 1208 with their finger and apply a linear force to the upper body 1212 with their thumb. Movement of the upper body 1212 relative to the lower body 1214 can create tension in the tether 1216. The tension in the tether can apply an injection force to the plunger 1204 via the pulley wheel. The syringe 1200 can achieve a mechanical advantage that increases the injection force compared to the linear force applied by the user. Because both ends of the line act in concert, each end applying a line force equal to the linear force, the injection force on the pulley wheel can be twice the linear force. The upper body 1212 can move longitudinally relative to the lower body 1214 by a first amount. The plunger 1204 can move longitudinally relative to the lower body 1214 by a second amount. The first amount can be greater than the second amount.

[0110] Figure 12C illustrates the principle of the mechanical advantage provided by a pulley: a wire pulled with a force of 50 N will exert a force of 100 N on the pulley.

[0111] The injection device 1200 may be reusable. A user can disengage the upper body from the lower body 1214. The syringe 102 can be removed from the housing 1210 and replaced. The upper body 1212 can then be coupled to the lower body 1214, and the injection device 1200 can then be ready for use.

[0112] 13A-13F illustrate another embodiment of an injection device 1300. The injection device 1300 may be a power-assisted injection device for administering a liquid medication. The injection device 1300 may be transitionable between a ready configuration (FIGS. 13A-13B), a first firing configuration (FIGS. 13C-13D), and a second firing configuration (FIGS. 13E-13F). The injection device 1300 may be adapted to provide a change in injection force during an injection. For example, the injection device 1300 may provide a first injection force during a first phase of an injection and a second injection force during a second phase of an injection. The second force may be greater than the first force.

[0113] The injection device 1300 may include a housing 1310 having a housing body 1312 adapted to receive the syringe 102. The housing 1310 has a first end and a central axis A. 13 and a second end spaced from the first end along a central axis A. 13 may extend in a longitudinal direction L. The longitudinal direction LA may be perpendicular to the longitudinal direction L. The transverse direction T may be perpendicular to each of the longitudinal direction LA and the longitudinal direction L. The syringe 102 may be fixed relative to the housing 1310. The plunger 1304 may be movable relative to the syringe 102 and may dispense a medication from a needle connected to the syringe. The plunger 1304 may form a liquid seal with a sidewall of the barrel.

[0114] The inner frame 1320 may be coupled to the plunger 1304. The injection device 1300 may be adapted to apply an injection force to the inner frame 1320 such that the inner frame 1320 moves the plunger 1304 relative to the housing 1310. The inner frame 1320 may be fixed to the plunger 1304. Alternatively, the inner frames 1320 may be movable apart and engage with each other during injection. The inner frame 1320 may be adapted to house a power source for moving the inner frame 1320 relative to the housing body 1312. The inner frame 1320 may include a sidewall 1322 defining a channel 1324 for receiving a motive force device.

[0115] The inner frame 1320 can be adapted to receive the first flange 1318. The first flange 1318 can extend across the lateral width of the inner frame 1320. The first flange 1318 can divide the channel 1324 of the inner frame 1320 into a first channel and a second channel. The first flange 1318 can be movable relative to the inner frame 1320. The first flange 1318 can move longitudinally relative to the inner frame 1320. The inner frame 1320 can translate longitudinally relative to the housing body 1312, while the first flange 1318 remains longitudinally fixed relative to the housing body 1312.

[0116] The end wall 1321 may be coupled to the inner frame 1320. The end wall 1321 may be fixed to the inner frame 1320 such that the end wall 1321 moves with the inner frame 1320 relative to the housing body 1312. The end wall 1321 may be fixed to the side wall 1322. The end wall 1321, the side wall 1322, and the plunger 1304 may be a unitary structure.

[0117] The injection device 1300 may include a latch 1306 adapted to define a locked position that prevents movement of the plunger 1304 and an unlocked position that allows movement of the plunger 1304. The latch 1306 may be movable relative to the housing body 1312. The latch 1306 may be movable relative to the housing body 1312 from a locked position ( FIG. 13A ) to an unlocked position ( FIG. 13C ). The latch 1306 may be a cantilever extending from the housing body 1312. The latch 1306 may be bendable relative to the housing body 1312 from the locked position to the unlocked position. The latch 1306 may be bendable laterally outward relative to the housing body 1312 from the locked position to the unlocked position.

[0118] The injection device 1300 may include a needle guard 1350 movable relative to the housing between an extended position ( FIG. 13A ) and a retracted position ( FIG. 13C ). The needle guard 1350 may be configured to at least partially surround the needle when the needle guard 1350 is in the extended position. The needle guard 1350 may encase at least a portion of the syringe 102 in the extended position. The needle guard 1350 may extend distally beyond the distal end of the needle when the needle guard 1350 is in the extended position. At least a portion of the needle guard 1350 may extend within the housing 1310. Movement of the needle guard 1350 may be configured to actuate the injection device 1300. A proximal end (not shown) of the needle guard 1350 may move the latch 1306 when the needle guard 1350 moves from the extended position to the retracted position.

[0119] The latch 1306 may include a first tooth 1326 adapted to engage the first flange 1318. The first tooth 1326 may prevent the first flange 1318 from moving distally in a longitudinal direction relative to the housing body 1312 when the latch 1306 is in the locked position. The latch 1306 may include a second tooth 1328 adapted to engage the second flange 1316. The second flange 1316 may be coupled to the inner frame 1320. The second flange 1316 may be coupled to a side wall 1322 of the inner frame 1320. The second flange 1316 may be coupled to a proximal end of the side wall opposite the end wall 1321.

[0120] The second flange 1316 can be adapted to engage the second tooth 1328 to move the latch 1306 from the locked position to the released position. One of the second flange 1316 and the second tooth 1328 can include an angled surface such that axial movement of the second flange 1316 relative to the second tooth 1328 moves the latch 1306 laterally outward.

[0121] The first flange 1318 can be engaged with the first teeth 1326 when the second flange 1316 begins to engage with the second teeth 1328. The first flange 1318 can disengage from the first teeth 1326 when the latch 1306 moves to the released position. Radial lateral outward movement of the latch 1306 can allow the first flange 1318 to disengage from the first teeth 1326.

[0122] The injection device 1300 may include a first latch, and the latch 1306 may be a second latch. The first latch may be movable from a locked position to an unlocked position. Movement of the first latch may engage an actuator of the first power source 1338 to initiate an injection. Movement of the first latch may allow the inner frame 1320 to move relative to the housing body 1312 while the latch 1306 is in the locked position.

[0123] The injection device 1300 may include a motive force device 1336 for applying an injection force to the plunger 1304. The injection device 1300 may be adapted to administer a liquid medicament upon release of the latch 1306 from a locked position, at least in part via the motive force device 1336. The motive force device 1336 may include a first power source 1338 and a second power source 1340. The first power source 1338 and the second power source 1340 may each be positioned within the channel 1324. The first power source 1338 may be positioned within a first portion of the channel 1324 and the second power source 1340 may be positioned within a second portion of the cavity, with the first flange 1318 separating the first and second portions of the cavity.

[0124] The first power source 1338 can be in compression between the first flange 1318 and the end wall 1321. The second power source 1340 can be in compression between the first flange 1318 and the housing body 1312. The second power source 1340 can apply a force greater than that applied by the first power source 1338. The second power source 1340 applies the greater force to overcome any pressure at the injection site as a result of the medication being delivered to the injection site.

[0125] The first power source 1338 can provide a first injection force during a first stage of the injection. The second power source 1340 can provide a second injection force during a second stage of the injection. The first power source 1338 and the second power source 1340 can each be a spring. The first power source 1338 and the second power source 1340 can be arranged in series such that the first power source 1338 provides the injection force during the first stage of the injection and the second power source 1340 provides the injection force during the second stage of the injection. In other embodiments, the first power source 1338 can provide power during the first stage of the injection, and the first power source 1338 and the second power source 1340 both contribute to the injection force during the second stage of the injection. In yet other embodiments, the first stage overlaps with the second stage such that the first power source 1338 applies an injection force, then both the first power source 1338 and the second power source 1340 apply an injection force, and then the second power source 1340 applies an injection force alone. The first power supply 1338 and the second power supply 1340 may be adapted to operate at least partially in series, e.g., the injection forces provided by each of the first power supply 1338 and the second power supply 1340 may not be applied completely simultaneously.

[0126] A first stage of the injection can begin when the plunger 1304 begins to move relative to the housing body 1312. A second stage of the injection can begin when the second flange 1316 engages the second tooth 1328, transitioning the latch 1306 to the released position. The first flange 1318 can be fixed relative to the housing body 1312 during the first stage and longitudinally movable relative to the housing body 1312 during the second stage.

[0127] The second flange 1316 can engage with the latch 1306 to lock the inner frame 1320 in a second position after injection. The second flange 1316 can move distally along the longitudinal axis L during injection such that the proximal end of the second flange 1316 is positioned distal to the distal end of the latch 1306 (FIG. 13F). The latch 1306 moves distally along the longitudinal axis A after the second flange 1316 passes the first tooth 1326. 13The distal end of the latch 1306 can engage the proximal end of the second flange 1316 to inhibit or prevent proximal movement of the inner frame 1320 and lock the inner frame 1320 in the second position.

[0128] Those skilled in the art will understand that changes can be made to the embodiments described above without departing from the broad inventive concept. Furthermore, it should be understood that the structures, mechanisms, and methods described above with respect to any of the embodiments described herein may be incorporated into any of the other embodiments described herein, unless otherwise specified. It is therefore understood that the present invention is not limited to the particular embodiments disclosed, but encompasses modifications that are within the spirit and scope of the present disclosure. Furthermore, it should be understood that the term substantially indicates that certain directional components are not absolutely perpendicular to one another, and that substantially perpendicular means that the direction has a primary directional component that is perpendicular to another direction.

Claims

1. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a plunger and a barrel adapted to hold the liquid medicament; a housing including a body adapted to hold the syringe and a latch configured to define a locked position that prevents movement of the plunger and an unlocked position that allows movement of the plunger, the housing including a first end and a second end opposite the first end along a central axis, the plunger configured to move in a first direction toward the second end to administer the medicament; a motive force device coupled to the second end of the housing, the motive force device configured to apply an injection force to the plunger to administer the medication while the latch is in the released position; and Including, configured to dispense the liquid medicament upon release of the latch from the locked position at least in part via the motive force device that applies the injection force to the plunger of the syringe. Power-assisted injection device.

2. 2. The injection device of claim 1, wherein the motive force device is at least one spring engaged with the body of the housing.

3. 3. The injection device of claim 2, wherein the housing includes a flange configured to translate relative to the housing body and configured to contact the plunger to apply the injection force to the syringe.

4. 4. The injection device of claim 3, wherein the housing includes a base proximal to the top of the barrel of the syringe, and the at least one spring of the prime mover device is a pair of springs in tension between the housing base and the housing flange.

5. 5. The injection device of claim 4, wherein the latch is a protrusion in the housing that contacts the underside of the housing flange when the latch is in the locked position, thereby holding the housing flange in the locked position until released.

6. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a plunger and a barrel adapted to hold the liquid medicament; a housing including a body adapted to hold the syringe and a latch configured to define a locked position that prevents movement of the plunger and a released position that allows movement of the plunger; a motive force device configured to apply an injection force to the plunger while the latch is in the released position to administer the medication; Including, the injection device is configured to administer the liquid medicament upon release of the latch from the locked position at least in part via the motive force device that applies the injection force to the plunger of the syringe; the motive force device is a spring coaxial with the plunger; Power-assisted injection device.

7. 7. The injection device of claim 6, further comprising a flange configured to translate relative to the housing body and configured to contact the plunger to apply the injection force to the syringe.

8. 8. The injection device of claim 7, wherein the spring is in tension between the base structure and the flange while the latch is in the locked position.

9. 8. The injection device of claim 7, wherein the latch is a protrusion in the housing that contacts the underside of the housing flange when the latch is in the locked position, thereby holding the housing flange in the locked position until released.

10. 4. The injection device of claim 3, wherein the housing includes a base proximal to the top of the housing body, and the at least one spring of the motive force device is a pair of springs that are in a compressed state between the housing base and the housing flange when the latch is in the locked position.

11. 11. The injection device of claim 10, wherein the latch is a protrusion in the housing that contacts the underside of the housing flange when the latch is in the locked position, thereby holding the housing flange in the locked position until released.

12. 2. The injection device of claim 1, wherein the motive force device is a pair of magnetic components, each of the magnetic components being a magnet and / or an iron structure, whereby an attractive force between the pair of magnetic components applies the injection force to the plunger.

13. 13. The injection device of claim 12, wherein a first of the pair of magnetic components is fixed relative to the housing proximal to the syringe barrel, and a second of the pair of magnetic components is coupled to the plunger at or near a plunger flange.

14. 14. The injection device of claim 13, wherein the first of the pair of magnetic components is a first magnet and the second of the pair of magnetic components is a second magnet oriented to attract the first magnet.

15. 14. The injection device of claim 13, wherein the magnets are spaced apart until the administration of the medication is complete.

16. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a plunger and a barrel adapted to hold the liquid medicament; a housing including a body adapted to hold the syringe and a latch configured to define a locked position that prevents movement of the plunger and a released position that allows movement of the plunger; a motive force device configured to apply an injection force to the plunger while the latch is in the released position to administer the medication; Including, the injection device is configured to administer the liquid medicament upon release of the latch from the locked position at least in part via the motive force device that applies the injection force to the plunger of the syringe; the motive force device being a first spring and a second spring, the first spring and the second spring being configured to operate at least partially in series; Power-assisted injection device.

17. 17. The injection device of claim 16, wherein the housing includes a divider separating the first spring from the second spring, the divider configured to move relative to the housing body.

18. 18. The injection device of claim 17, wherein the latches are first and second latches, and release of the first latch engages an actuating portion of the first spring, and release of the second latch engages an actuating portion of the second spring.

19. 19. The injection device of claim 18, wherein the housing further comprises an inner frame configured to engage the plunger, the inner frame being movable relative to the housing body and the divider, wherein upon release of the first latch and before release of the second latch, the first spring moves from a compressed position to an extended position, and wherein upon release of the second latch, the second spring moves from the compressed position to the extended position.

20. 20. The injection device of any one of claims 1 to 19, wherein the translatable housing flange comprises a contact portion configured to be contacted by a user to move the housing flange upwards and reset the motive force device.

21. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a plunger and a barrel configured to hold the liquid medicament; at least one spring configured to apply an injection force to the plunger to administer the medication; a housing including a body configured to hold the syringe and a flange configured to translate relative to the housing body and configured to contact the plunger and apply the injection force to the syringe; a load actuator configured to apply a load to the spring; Including, the injection device is configured to administer the liquid medication upon loading of the spring. Power-assisted injection device.

22. 22. The injection device of claim 21, wherein the loading actuator includes a linkage assembly configured to move the at least one spring from a fired position to a ready position.

23. 23. The injection device of claim 22, wherein the linkage assembly includes a lever arm assembly including a lever arm and a pivot fixed to the body of the housing.

24. 24. The injection device of claim 23, wherein the linkage assembly further includes at least one linkage arm pivotally connected to an inner end of the lever arm, whereby application of a force to the lever arm transmits a load force upwardly through the linkage arm to compress the at least one spring.

25. 24. The injection device of claim 23, wherein (i) the linkage assembly further comprises a linkage arm pivotally connected to an inner end of the lever arm, (ii) the at least one spring is a pair of springs engaged to opposite ends of the housing flange, and (iii) the at least one linkage arm is a pair of linkage arms engaged to opposite ends of the housing flange, whereby when a force is applied to the lever arm, a load force is transmitted upward through the linkage arms to compress the spring.

26. 23. The injection device of claim 22, wherein the spring is a coaxial spring disposed around the plunger.

27. 22. The injection device of claim 21, wherein the housing includes a removable base flange configured to engage the syringe, the base flange located at a distal portion of the housing base.

28. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a barrel configured to hold the liquid medication and a piston configured to administer the medication; a housing including a body configured to hold the syringe; a barb assembly located within the housing, the barb assembly including a barb and a support structure configured to support the barb; a plenum defined by at least the housing and the piston of the syringe; a compressed gas canister configured to be movable relative to the barb, the gas canister having a ready position in which the gas canister is sealed and spaced apart from the barb, and an engaged position in which the gas canister is in contact with the barb such that the barb pierces a seal on the gas canister; Including, When the barb penetrates the gas canister seal, gas pressurizes the plenum and applies the injection force to the piston, thereby driving the piston against the barrel of the syringe to administer the medication. Power-assisted injection device.

29. 29. The injection device of claim 28, wherein the housing includes an opening in slidable contact with the gas canister, whereby the gas canister slides within the opening when moving from the ready position to the engaged position.

30. 30. The injection device of claim 29, wherein the barb assembly is fixed relative to the housing.

31. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a container including a barrel configured to hold the liquid medicament and a stopper configured to seal the barrel, the stopper being movable relative to the container to apply an injection force to the liquid medicament in the barrel; a housing including a body configured to hold the container, wherein a first housing helical thread on an inner surface of the body defines a first pitch and a second housing helical gear thread on an inner surface of the body defines the second pitch; an actuator configured to engage the first housing helical thread and the second housing helical thread and to apply the injection force to the bung; 1. A power-assisted injection device comprising:

32. 32. The injection device of claim 31 , wherein the actuator comprises a first member and a second member configured to rotate relative to one another when the user applies a linear force to the actuator, the first member gear having a pitch different from the pitch of the second member to provide a mechanical advantage to the force applied to the actuator by the user.

33. the actuator includes a first member and a second member; the first member gear includes a first member body and threads on an outer surface of the first member body, the threads configured to engage the first housing body helical gear threads; the second member includes a second member body and threads on an outer surface of the second member body, the threads configured to engage the second housing body helical gear threads; the first member and the second member are rotationally constrained relative to each other, and rotation of one of the first member and the second member transmits torque to the other of the first member and the second member; the second member has a pitch different from the pitch of the first member; 32. An injection device according to claim 31.

34. the actuator includes a first member and a second member; the first member includes a first member body, a shaft secured to and extending coaxially from the first member body, and threads on an outer surface of the first member body, the threads having the first pitch, the first member threads configured to engage the first housing body helical gear threads; the second member includes a second member body, a recess configured to receive the shaft of the first member and rotationally constrained to the shaft, and threads on an outer surface of the second member body having the second pitch, the second member threads configured to engage the second housing body helical gear threads; a linear force applied to the first member rotates the first member due to engagement with the first inner housing thread, the rotation of the first member transmits rotation to the second member via the shaft and the recess, the first pitch of the first member is greater than the second pitch of the second member, and thus the second member has a translation that is less than the translation of the first member; 32. An injection device according to claim 31.

35. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a container including a plunger and a barrel configured to hold the liquid medicament; a housing including a lower body, an upper body, and a coaxial pinion pair, the housing upper body configured to receive a linear force, the pinion pair including a first pinion and a second pinion having a common pinion shaft; Including, the housing upper body includes a rack configured to engage with teeth of the first pinion, and the housing lower body includes a rack configured to engage with teeth of the second pinion and configured to apply an injection force to the plunger of the container; a linear force applied to the upper housing body relative to the lower housing body translates the upper housing rack and rotates the first pinion and the second pinion, the second pinion transmitting movement to the lower housing body rack, thereby translating the lower housing body and applying the injection force to the plunger; A power-assisted injection device, wherein the pitch of the first pinion and upper body rack is greater than the pitch of the second pinion and lower body rack, such that the housing lower body moves less than the housing upper body in response to a unit movement of the housing upper body.

36. 36. The injection device of claim 35, wherein the housing includes a removable tip that engages with the housing lower body, the removable tip engaging the container to allow replacement thereof.

37. 1. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe including a plunger and a barrel configured to hold the liquid medicament; a housing including a lower body and an upper body movable relative to the lower body; a pulley assembly including a pulley wheel and a tether extending around the pulley wheel, the tether having a first end and a second end, the first end coupled to the upper body and the second end coupled to the lower body, the pulley wheel engaging the plunger; Movement of the upper body relative to the lower body creates tension in the tether, which in turn creates an injection force on the plunger via the pulley wheel. Power-assisted injection device.

38. 38. The injection device of claim 37, wherein the lower body includes a flange configured to engage a user's finger.

39. 38. The injection device of claim 37, wherein movement of the upper body results from a user force applied via a flange on the housing lower body.

40. 38. The injection device of claim 37, wherein the tether is one of a wire, a string, and a belt.

41. An injection device according to any one of the preceding claims, further comprising a passive needle guard.

42. 10. The injection device of claim 1, wherein the liquid medication has a viscosity of at least 10 centipoise at 20°C.

43. 2. The injection device of claim 1, wherein the housing defines a recess extending from the first end toward the second end, and the plunger is disposed within the recess and configured to move distally toward the second end to administer the medicament.

44. The injection device of claim 1 , wherein the recess extends through the first end of the housing.

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