Power assist for injection devices of manual and automatic injection devices

Abstract

A power assisted injection device may apply a liquid drug. The injection device may include a syringe, a housing, and a motive power device. The syringe may include a plunger and a barrel configured to hold the liquid medicament. The housing may include a body configured to hold the syringe. The housing may also include a latch configured to define a locked position that inhibits movement of the plunger and a released position that enables movement of the plunger. The motive power device may be configured to apply an injection force to the plunger to apply the medicament when the latch is in the released position. The injection device may be configured to apply the liquid medicament at least partially via the prime power device that applies the injection force to the plunger of the syringe when the latch is released from the locked position.

Description

Background Art

[0001] Subcutaneous injections are commonly used to deliver medications to patients using various injection devices, such as syringes, needle safety devices, and various automatic injection devices. Examples of needle safety devices include the UltraSafe Injection System and UltraSafe Plus Injection System sold by Becton, Dickinson and Company.

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

[0003] Existing automatic injection devices may require the user to remove a cap, place the device (with the needle hidden by the needle guard) against the skin and push down with force. The start of delivery is triggered by pushing a button or by depressing the needle guard. The user continues to hold the device against the skin until delivery is complete. To deliver a drug with high viscosity and / or high volume, the user may be required to apply greater force and / or inject for a longer period of time and at a higher frequency (relative to lower viscosity and / or lower volume). In any of these situations, the user may experience hand discomfort or fatigue. Therefore, there is a need for an improved injection device. Summary of the invention

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

[0005] A power-assisted injection device for administering a liquid drug may include a syringe, at least one spring, a housing, and a load actuator. The syringe may include a plunger and a barrel configured to hold the liquid drug. The at least one spring may be configured to apply an injection force to the plunger to administer the drug. 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 load actuator may be configured to load the spring. The injection device may be configured to administer the liquid drug when the spring is loaded.

[0006] A power-assisted injection device for administering a liquid drug may include a syringe, a housing, a barb assembly, a plenum chamber, and a compressed gas tank. The syringe may include a barrel configured to hold the liquid drug and a piston configured to administer the drug. The housing may include a body configured to hold the syringe. The barb assembly may be located within the housing and may include a barb and a support structure configured to support the barb. The plenum chamber may be defined by at least the housing and the piston of the syringe. The compressed gas tank may be configured to be movable relative to the barb. The gas tank may have a ready position and an engaged position, in which the gas tank is sealed and spaced apart from the barb, and in which the gas tank contacts the barb so that the barb pierces the seal of the gas tank. The barb piercing the seal of the gas tank may allow gas to pressurize the plenum chamber to apply the injection force to the piston, thereby driving the piston relative to the barrel of the syringe to administer the drug.

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

[0008] A power-assisted injection device for administering a liquid drug may include a cartridge and a housing. The cartridge may include a plunger and a barrel configured to hold the liquid drug. The housing may include a lower body, an upper body, and a coaxial pinion pair, the coaxial pinion pair including a first pinion and a second pinion having a common pinion axis. The housing upper body may be configured to receive a linear force. The housing upper body may include a rack configured to engage the teeth of the first pinion. The housing lower body may have a rack configured to engage the teeth of the second pinion and configured to apply an injection force to the plunger of the cartridge. A linear force applied to the housing upper body relative to the housing lower body may cause the housing upper body rack to translate to rotate the first pinion and the second pinion, and the second pinion transmits movement to the housing lower body rack, thereby translating the housing lower body to apply the injection force to the plunger. The pitch of the first pinion and the upper body rack may be greater than the pitch of the second pinion and the lower body rack so 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 drug may include a syringe, a housing, and a pulley assembly. The syringe may include a plunger and a barrel configured to hold the liquid drug. 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, wherein the first end is coupled to the housing upper body and the second end is coupled to the housing lower body. The pulley wheel may engage with the syringe plunger. Movement of the housing upper body relative to the housing lower body may generate tension in the tether, thereby generating an injection force on the plunger via the pulley wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A is a view of a power-assisted injection device with dual extension springs shown in a locked, extended position;

[0011] Figure 1B is an example of a spring in a retracted position when released from a locked position. Figure 1A A view of an implementation scheme of the device;

[0012] Figure 1C is an illustration of a needle guard deployed over a needle after actuation of an injection device and delivery of a drug Figure 1A A view of an implementation scheme of the device;

[0013] Figure 2A is a schematic diagram of a second embodiment power-assisted injection device employing a single spring shown in a locked, extended position;

[0014] Figure 2B is shown in the unlocked, extended position Figure 2A A schematic diagram of a second embodiment of the device;

[0015] Figure 2C is an illustration of a spring in a fully retracted position associated with complete administration of a drug. Figure 2B A schematic diagram of a second embodiment of the device;

[0016] Figure 2D is after activation of the spring-loaded needle guard above the needle Figure 2C A schematic diagram of a second embodiment of the device;

[0017] Figure 3A is a schematic diagram of a third embodiment power-assisted injection device employing dual springs in compression shown in a locked, retracted position;

[0018] Figure 3B is shown in the unlocked, retracted position Figure 3A A schematic diagram of a third embodiment of the device;

[0019] Figure 3C is an illustration of a spring in a fully extended position associated with full administration of a drug. Figure 3B A schematic diagram of a third embodiment of the device;

[0020] Figure 3D is after activation of the spring-loaded needle guard above the needle Figure 2C A schematic diagram of a third embodiment of the device;

[0021] Figure 4A is a perspective view of a fourth embodiment injection device prior to actuation of the plunger;

[0022] Figure 4B is an enlarged, partially cut-away view illustrating a gas tank and plunger in a ready position;

[0023] Figure 4C is a schematic diagram of a fourth embodiment of a power-assisted injection device using a gas canister illustrated in an intact (unpunctured) ready position;

[0024] Figure 4D is an illustration of a gas canister that has been actuated by puncture and a piston in a fully actuated position associated with complete administration of a drug. Figure 4A A schematic diagram of a fourth embodiment of an apparatus;

[0025] Figure 5Ais a schematic diagram of a fifth embodiment power-assisted injection device employing magnets illustrated in a spaced-apart, ready position with the plunger fully extended;

[0026] Figure 5B is an illustration of the attractive force between a magnet and a partially actuated plunger. Figure 5A A schematic diagram of a fifth embodiment of the device;

[0027] Figure 5C is an illustration of a magnet in contact and a plunger in a fully actuated position associated with complete administration of a drug. Figure 5B A schematic diagram of a fifth embodiment of the present invention;

[0028] Fig. 6A is a partially transparent perspective view of a sixth embodiment of a power-assisted injection device including a pair of springs and a spring return device, illustrating a lever of the return device in a downward position and a spring in a preloaded ready position;

[0029] Figure 6B is with Fig. 6A The view is relative to Fig. 6A A perspective view of a sixth embodiment of the apparatus;

[0030] Figure 6C is an illustration of a lever in an upward or retracted position and a device in a ready position Fig. 6A A partially transparent perspective view of a sixth embodiment of the present invention;

[0031] Fig. 7A is an example Figure 6C a schematic diagram of the apparatus of the sixth embodiment shown in a ready position;

[0032] Figure 7B is a schematic diagram illustrating a sixth embodiment device of the spring in a fully extended position associated with full administration of a drug;

[0033] Figure 7C This is an example of Fig. 6A a schematic diagram of a sixth embodiment of the apparatus showing the lever in the downward position;

[0034] Fig. 8A is a schematic diagram of a seventh embodiment power-assisted injection device employing dual springs in compression shown in a locked, retracted position, including surfaces for enabling resetting of the device;

[0035] Figure 8B is an illustration of a spring in a fully extended position associated with full administration of a drug. Fig. 8A A schematic diagram of a third embodiment of the device;

[0036] Fig.9Ais a perspective, partial cross-sectional view of an eighth embodiment power-assisted injection device employing a single spring shown in a locked, extended position, with the spring in tension and the reset device in an upward position;

[0037] Fig. 9B yes Fig.9A A side partial cross-sectional view of an eighth embodiment of the device;

[0038] Fig. 9C is an illustration of a spring in a fully retracted position associated with complete administration of a drug. Fig. 9B A side partial cross-sectional view of an eighth embodiment of the device, wherein the reset device has not yet been engaged;

[0039] Fig.9D After activation of the lever of the reset device has moved the spring back to its extended, ready position Fig. 9C A partial side cross-sectional view of an eighth embodiment of the device;

[0040] Fig.9E The base is shown removed from the actuator to illustrate the engagement of the reusable base with the syringe. Fig.9A The base portion of the eighth embodiment of the device;

[0041] Fig. 10A is a perspective view of a ninth embodiment power-assisted injection device employing a helical gear driven plunger for providing a mechanical advantage to a user, the plunger being shown in an extended, ready position;

[0042] Fig. 10B yes Fig. 10A A schematic cross-sectional view of a ninth embodiment of a device;

[0043] Fig. 10C yes Fig. 10A A schematic cross-sectional view of the apparatus of the ninth embodiment shown in a ready position;

[0044] Fig. 10D yes Fig. 10A A schematic cross-sectional view of the apparatus of the ninth embodiment shown in a ready position;

[0045] Fig.10E is a schematic cross-sectional view of a ninth embodiment device illustrating a plunger (not shown) in an actuated position associated with complete administration of a drug product;

[0046] Fig.10F yes Fig.10E A perspective view of a ninth embodiment of the apparatus;

[0047] Figure 10G yes Fig.10E An enlarged cross-sectional view of a device;

[0048] Fig. 10H is an illustration of a needle guard deployed over a needle after actuation of an injection device and delivery of a drug Figure 10G An enlarged cross-sectional view of a device;

[0049] Fig.10I yes Fig. 10H an enlarged perspective cutaway view of the device shown;

[0050] Fig.10J is an illustration of a needle guard deployed over a needle after actuation of an injection device and delivery of a drug Fig. 10H An enlarged perspective cross-sectional view of a device;

[0051] Fig.11A is a perspective view of a tenth embodiment of a power-assisted injection device using a double rack and pinion;

[0052] Fig. 11B is an illustration of a plunger in an extended, ready, unactuated position Fig.11A A schematic diagram of a tenth embodiment of an apparatus;

[0053] Fig. 11C is an illustration of a plunger in an extended, ready, unactuated position Fig. 11B A cross-sectional view of a device;

[0054] Fig.11D is an illustration of a plunger in an extended, ready, unactuated position Fig. 11B A perspective partial cutaway view of an embodiment of;

[0055] Fig.11E is an illustration of a plunger in a partially actuated position Fig.11D A perspective partial cutaway view of an embodiment of the device;

[0056] Fig.11F is a diagram illustrating a plunger in an actuated position associated with complete administration of a drug. Fig.11D A perspective partial cutaway view of an embodiment of the device;

[0057] Fig.11G is a diagram illustrating a plunger in an actuated position associated with complete administration of a drug. Fig.11A A schematic diagram of an implementation scheme of the device;

[0058] Fig.11H is a diagram illustrating a plunger in an actuated position associated with complete administration of a drug. Fig.11A A perspective view of an embodiment of the device;

[0059] Fig.11I is to illustrate the ability to remove the cap so that the syringe can be replaced Fig.11A An exploded perspective view of a portion of the apparatus of the ninth embodiment is shown;

[0060] Fig. 12A is a schematic diagram of an eleventh embodiment of a power-assisted injection device employing a pulley system for mechanical advantage illustrating a plunger in an extended, ready position;

[0061] Fig. 12B is an illustration of a plunger in a fully actuated position associated with complete administration of a drug. Fig. 12A A schematic diagram of an implementation scheme of the device;

[0062] Fig. 12C Example of Fig. 12A The implementation scheme of the device adopts the principle of mechanical advantage;

[0063] Fig.13A is a schematic diagram of a twelfth embodiment of a power-assisted injection device in an extended, ready position and employing a pair of springs in series so that the force applied to the syringe plunger can be varied during actuation;

[0064] Fig. 13B yes Fig.13A An enlarged schematic diagram of an injection device;

[0065] Fig. 13C is an example of a first spring in an extended position to place the syringe in a partially actuated position Fig.13A Schematic diagram of the injection device;

[0066] Fig.13D yes Fig. 13C An enlarged schematic diagram of an injection device;

[0067] Fig.13E is an example of a second spring in an extended position to place the syringe in its fully actuated position associated with full administration of the drug. Fig.13A A schematic diagram of an injection device; and

[0068] Fig.13F yes Fig.13E An enlarged schematic diagram of the injection device. DETAILED DESCRIPTION

[0069] The injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) may be a power-assisted injection device that administers a medicament from a syringe. The medicament may be a viscous liquid drug. The viscous liquid drug may have a viscosity of about 10 centipoise to about 375 cp at 20 degrees Celsius. The injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) may be adapted to receive a syringe 102 ( Figure 1A ). The syringe 102 may be adapted so that a user can manually perform an injection without 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 a medicament without the assistance 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 workload of the user administering the injection. The syringe 102 may include a barrel 122 adapted to hold a liquid drug. The flange 103 may extend radially outward from the barrel 122. The flange 103 may engage the housing to prevent axial movement of the syringe 102 during injection. The flange 103 may be disposed at the proximal end of the syringe 102.

[0070] The drug can be delivered to the patient from the barrel 122 through the discharge port 124. In some examples, the discharge port 124 is a needle. In other examples, the discharge port 124 is a cannula. In other examples, the discharge port 124 is an opening in the barrel so that an injection device (e.g., 100, 200, 300, 400, 500, 600, 800, 900, 1000, 1100, 1200, or 1300) delivers a needle-free injection. The discharge port 124 can be in fluid communication with the barrel 122 so that liquid drug can be delivered to the patient from the barrel 122 and through the discharge port 124. The discharge port 124 can be disposed at the distal end of the syringe 102. The plunger 126 can be movably received in the barrel 122. The plunger 126 can provide a liquid seal with the barrel 122. The plunger 126 may be movable relative to the barrel 122 such that movement of the plunger 126 toward the discharge port 124 forces the medicament out of the discharge port 124 .

[0071] 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 feature that automatically extends without additional steps from the user. The distal end of the needle guard 121 may include an opening, and when the needle guard 121 is not extended, the discharge port 124 or at least a portion of the syringe 102 may extend through the opening. 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 fixed and axially fixed relative to the housing 104.

[0072] The piston 128 can be operatively associated with the plunger 126. Being 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 integrally constructed. 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 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 transitioned from the pre-injection configuration to the injection configuration, the piston 128 can be axially moved into engagement with the plunger 126. In other embodiments, 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, the piston 128 engages the plunger 126. In some embodiments, the injection device 100 can be reused by replacing the syringe 102, such that the piston 128 remains coupled to the housing 104 when the syringe 102 is replaced. In other embodiments, the piston 128 is associated with the syringe 102 so that the piston 128 is decoupled from the housing 104 when the syringe 102 is replaced.

[0073] Reference now Figures 1A to 1C , shows an injection device 100. The injection device 100 may be configured from a pre-injection configuration ( Figure 1A )Move to the injection configuration ( Figure 1B The injection device 100 may be capable of moving from an injection configuration to a post-injection configuration ( Figure 1C ).

[0074] 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 size and shape of the housing 104 may be designed 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 to receive at least a portion of the syringe 102. The housing body 118 may define a recess to receive 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 detachably coupled to the housing body 118. The syringe 102 may be fixed relative to the housing 104 during injection. After the medicament is dispensed from the syringe 102, the syringe 102 may be able to move relative to the housing 104, as explained in more detail below.

[0075] 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 the piston 128 and move it 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 integrally constructed. When the injection device 100 is in the pre-injection configuration, the flange 130 may be axially spaced apart from the piston 128. When the injection device 100 is converted from the pre-injection configuration to the injection configuration, the flange 130 may be moved to engage with the piston 128. In other embodiments, when the injection device 100 is in the pre-injection configuration, the flange 130 is in contact with the piston 128.

[0076] The user may apply force to the flange 130 to move the flange 130 relative to the housing body 118. The distal end of the housing body 118 may include a finger flange 108 so that the user can engage the finger flange 108 with two fingers while engaging and applying force to the flange 130 with the thumb. The finger flange 108 may include an opening configured to receive the needle guard 121. The needle guard 121 may be removably received within the opening defined by the finger flange 108. The housing body 118 may include an opening 139 so that the user can move the flange 130 within the housing body 118.

[0077] The housing body 118 may include a latch 132 adapted to define a locked position that inhibits movement of the piston 128 and a released position that enables movement of the piston 128. The latch 132 may be any suitable latch that can define a locked position and a 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 so that when sufficient force is applied, one of the flange 130 and the latch 132 bends out of engagement with 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 prime mover 136. The initiating force may be about 15 Newtons to about 40 Newtons.

[0078] The injection device 100 may include a prime mover 136 adapted to apply an injection force to the plunger 126 to administer the drug when the latch 132 is in the released position. The injection force may be separate and distinct from the initiation force. The user may apply the initiation force and the prime mover 136 may apply the injection force. The initiation force may be applied during the initiation time period. The injection force may be applied during the injection time period. The initiation time period may be about 1 second. The injection time period 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 136 applies enough injection force to the plunger 126 to complete the injection, even if the user does not manually apply 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 drug at least in part via a motive force device 136 that applies an injection force to the plunger 126 of the syringe 102 when the latch 132 is released from the locked position. The motive force device 136 may apply an injection force to the plunger 126 via the piston 128. The injection force may be about 10 Newtons to about 25 Newtons, about 25 Newtons to about 50 Newtons, about 50 Newtons to about 75 Newtons, or about 75 Newtons to about 100 Newtons. In some examples, the injection device 100 includes a 27-gauge needle to deliver 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 to deliver a liquid having a viscosity of about 60 centipoise, and the injection force is about 50 Newtons for a 10-second injection.

[0079] In some embodiments, the prime mover 136 applies the injection force without requiring additional force from the user. In other embodiments, the injection force of the prime mover 136 is insufficient to move the plunger 126 while releasing the latch 132 without external force applied by the user. Thus, in addition to the force from the prime mover 136, the user must apply force to the flange 130 to perform the injection. The prime mover 136 can be coupled to the flange 130. Alternatively, the prime mover 136 can be coupled to the piston 128.

[0080] When the injection device 100 moves from the pre-fired configuration to the fired configuration, the prime mover 136 may transition from an expanded state to a relaxed state. The prime mover 136 may be a biasing element. The prime mover 136 may be at least one spring engaged with the housing body 118. The at least one spring may be a pair of springs engaged with the housing body 118. The housing body 118 may include a base 116 proximate an upper portion of the barrel 122. The at least one spring of the prime mover 136 may be in tension between the base 116 and the flange 130. Alternatively, the prime mover 136 may be a gas firing piston.

[0081] The injection device may include a syringe holder 141 (in Figure 1C ). The syringe holder 141 may be coupled to the barrel 122 of the syringe 102. The barrel 122 may be positionally fixed relative to the syringe holder in at least an axial direction when coupled to the syringe holder 141. The needle guard 121 may be configured to move axially relative to the syringe holder 141 to move between an initial position ( Figure 1A and Figure 1B ) and retracted position ( Figure 1C ), in which the distal end of the discharge port 124 extends out of the needle guard 121, and in which the distal end of the discharge port 124 is retracted into 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.

[0082] The return force device 134 can be adapted to move the syringe 102 from the injection position ( Figure 1B ) moves to the injection position ( Figure 1C). The return force device 134 may be a biasing element (e.g., a spring). The return force device 134 may apply forces to the needle guard 121 and the syringe holder 141 in opposite directions to move the syringe holder 141 (and thus the syringe 102) proximally relative to the housing 104 (including the needle guard 121). When the syringe 102 is in the post-injection position, the discharge port 124 may be located within the needle guard 121.

[0083] The flange 130 may include a first portion 138 and a second portion 140 ( Figure 1C ). The first portion 138 may be detachably coupled to the second portion 140. The prime mover 136 may be coupled to the second portion 140 such that the prime mover 136 moves the first portion 138 and the second portion 140 from the pre-injection position to the injection position. A latch (not shown) may couple the first portion 138 to the second portion 140. The first portion 138 and the second portion 140 may be moved together from the pre-injection position to the injection position.

[0084] The disengagement member 142 may be coupled to the housing body 118 and adapted to disengage the first portion 138 from the second portion 140. The disengagement member 142 may include a syringe holder 141 adapted to engage the syringe holder 141 to hold the needle guard 121 in an initial position ( Figure 1A and Figure 1B ) protrusion 144. At least one of the first portion 138 and the second portion 140 can cause the disengagement member 142 to disengage from the syringe holder 141, so that the return force device 134 can move the syringe 102 from the initial position to the retracted position ( Figure 1C ).

[0085] 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 uncoupling 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.

[0086] FIG. 2A to FIG. 2DAnother embodiment of an injection device 200 is illustrated. The injection device 200 may include a housing 210 adapted to receive a 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 to move 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 recessed portion, wherein at least a portion of the plunger 228 is within the recessed portion.

[0087] 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 integrally constructed. Movement of the first portion 204 relative to the second portion 206 may initiate an injection, as explained below. A portion of the first portion 204 may be nested within the second portion. 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. Coaxial with the second portion 206. The first portion central axis may be coaxial with the second portion central axis.

[0088] The housing 210 may include a latch 208 adapted to define a locked position that inhibits movement of the plunger 228 and a released position that enables movement of the plunger 228. The latch 208 may be configured to engage with the flange 202. For example, the latch 208 may engage with the second portion 206. In some embodiments, the latch 208 may be removable from the locked position ( Figure 2A ) moves to the release position ( Figure 2B ) When the latch 208 is in the released position, the flange 202 may be able to move relative to the housing 210.

[0089] The latch 208 may include a protrusion 212 ( Figure 2C ), to prevent axial movement of the flange 202 in the distal direction when the latch 208 is in the locked position. The latch 208 can hold the flange 202 in the locked position until released. The latch 208 can include an inclined surface 214 that can engage with the first portion 204. The first portion 204 can be capable of moving relative to the second portion 206 while the second portion 206 is engaged with the protrusion 212. For example, the first portion 204 can be capable of moving relative to the second portion 206 along the axis A2 ( Figure 2A) translation. Movement of the first portion 204 relative to the second portion 206 can 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 about 15N to about 40N. The first portion 204 can engage the inclined surface 214 so that the protrusion 212 moves out of engagement with the second portion 206. In some embodiments, the latch 208 includes a cantilever beam arm that bends radially outward away from the central axis of the housing 210 when the first portion 204 engages the inclined surface 214. When the latch 208 bends from the locked position to the released position, the latch 208 can move into contact with the inner surface of the housing 210.

[0090] The latch 208 may be a sidewall that extends continuously circumferentially around an opening that is sized to receive the flange 202. Alternatively, the latch 208 may be two or more sidewalls that are spaced apart from one another around the perimeter of the opening that defines the receiving flange 202.

[0091] A first end of the motive device 236 may be coupled to the flange 202. A second end of the motive device 236 may be coupled to the housing 210. For example, the motive device 236 may be coupled to the second portion 206 of the flange 202 and the distal portion of the housing 210. The motive device 236 may be in tension between the flange 202 and the distal portion of the housing 210.

[0092] 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 so that the needle is covered 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. In the post-injection position, the needle guard 220 may enclose at least a portion of the syringe 102. The needle guard 220 may extend distally beyond the distal end of the discharge port 124 when the needle guard is in the post-injection position. When the needle guard 220 is in the injection position, the discharge port 124 may extend distally from the distal end of the needle guard 220.

[0093] The needle guard 220 may be at least temporarily fixed relative to the housing 210 before injection. The needle guard 220 may include an arm 222 engaged with a lower wall 224 of the housing 210. The lower wall 224 may include an opening so that the arm 222 extends from a first side of the lower wall 224 to a second side of the lower wall 224 opposite to the first side along the axis A2. The arm 222 may include a pawl that can engage 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 may be movable from an engaged position to a disengaged position. The arm 222 may be a cantilever beam extending proximally from a proximal end of the body of the needle guard 220. The pawl of the arm 222 may engage with the lower wall 224 in the engaged position and disengage from the lower wall 224 in the disengaged position. The arm 222 may be flexible from the engaged position to the disengaged position. When the arm 222 is in the disengaged position, the needle guard 220 may be movable relative to the housing 210.

[0094] The flange 202 may be adapted to move the arm 222 from the engaged position to the disengaged position. The flange 202 may include a disengagement member 226 that moves the arm 222 when the flange 202 moves axially toward the lower wall 224. For example, one of the disengagement member 226 and the arm 222 may include an inclined surface that is engageable with the other of the disengagement member 226 and the arm 222, such that axial translation of the flange 202 moves the arm 222 radially into the disengaged position. When the arm 222 is in the disengaged position, the needle guard 220 may move from the injection position toward the post-injection position.

[0095] 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 protrusion 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 (in the Figure 2D ). The syringe holder 241 can be coupled to the barrel 122 of the syringe 102. The barrel 122 can be positionally fixed relative to the syringe holder in at least an axial direction when coupled to the syringe holder 241. The syringe holder 241 can be positionally fixed relative to the housing 210. The needle guard 220 can be configured to move axially relative to the syringe holder 241 to move between an injection position ( Figure 2A , Figure 2B and Figure 2C ) and injection position ( Figure 2D), in which the distal end of the discharge port 124 extends out of the needle guard 220, and in which the distal end of the discharge port 124 is retracted into the needle guard 220. In some examples, the syringe holder 241 and the needle guard 220 are part of the UltraSafe Plus injection system sold by Becton, Dickinson and Company.

[0096] 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 applies a force to the lower surface of the lower wall 224 or to the syringe holder 241. The biasing element 232 can include a second portion that applies a force to the needle guard 220. The biasing element 232 can be adapted to expand when the arm 222 is 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 so that the needle guard 220 expands when it is no longer constrained by the arm 222.

[0097] The injection device 200 may be reusable. The user may disengage the syringe holder 241 and the needle guard 220 from the lower housing 238 and remove the syringe 102. For example, the user may apply a radially inward force to disengage the arms 222 from the lower housing 238 and pull the needle guard 220 away from the lower housing 238. The user may then move the plunger 228 proximally until the second portion 206 engages the latch 208. The user may then insert a new syringe 102 into the needle guard 220. The needle guard 220 may then be reconnected to the housing 210 and moved proximally until the arms 222 engage the housing 210.

[0098] FIG. 3A to FIG. 3D Another embodiment of an injection device 300 is illustrated. The injection device 300 may be similar to the injection device 200. However, the motive device 336 of the injection device 300 may be different from the motive device 236 of the injection device 200. For example, the motive device 336 may include at least one spring in compression between the housing base 312 and the housing flange 338 when the latch 208 is in the locked position. The motive device 336 may be adapted to move the flange 202 relative to the housing 210 when the latch 208 is in the released position.

[0099] The housing 310 may include a base 312 proximate an upper portion of the housing body 318. The housing flange 338 may be a strip, 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 the alignment of the housing flange 338 relative to the housing 310 when the housing flange 338 is moved to the post-injection position. Maintaining the alignment of the housing flange 338 may help ensure smooth and complete delivery of the medicament dose. The housing flange 338 may include a central axis extending along the maximum 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.

[0100] Movement of the first portion 204 of the flange 202 relative to the second portion 206 may initiate an injection by moving the latch 208 to a released position, as previously discussed. The prime mover 336 may apply a force to the housing flange 338. The housing flange 338 may apply an injection force to the flange 202 in response to the force applied by the prime mover 336, causing the flange 202 to move relative to the housing 310. In some examples, the injection device 300 is configured to be coupled to an existing injection system. One injection system contemplated for use with the injection device 300 is the UltraSafePlus injection system sold by Becton, Dickinson and Company.

[0101] 4A to 4D Another embodiment of an injection device 400 is illustrated. The injection device 400 may include a housing 410 having a housing body 418 adapted to hold a syringe 102. The housing 410 may include a power source to move the syringe plunger 126 relative to the barrel 122. The power source may be a compressed gas tank 436. The gas in the tank may be hexafluoroacetone (HFA), liquefied petroleum gas, helium, nitrogen, oxygen, or VapourSoft manufactured by Recipharm AB headquartered in Stockholm, Sweden. Activating the tank 436 may release the compressed gas to move the syringe plunger 126.

[0102] The canister 436 may include a seal 404 that can be pierced or moved to allow compressed gas to leave the canister. The seal 404 may be positioned at the distal end of the canister 436. In some embodiments, the seal 404 may be a pierceable or frangible end portion of the canister 436. In other embodiments, the seal 404 may be a plug that engages the open sidewall of the canister 436, thereby sealing the canister.

[0103] The barb assembly 438 may be adapted to pierce or displace the seal 404 to allow gas to leave the canister 436. The barb assembly 438 may include a barb 440 adapted to pierce the seal 404. The barb 440 may have a pointed end that facilitates piercing the seal 404. Alternatively, the barb 440 may have a blunt or rounded end that pushes the seal 404 to disengage from the open sidewall of the canister 436. The barb 440 may include an opening extending therethrough to allow gas from the canister 436 to flow through the barb 440.

[0104] The barb assembly 438 may include a support structure 442 adapted to support the barb 440. The support structure 442 may fix the position of the barb assembly relative to the canister 436 during injection. The support structure 442 may 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 may have a height as measured along the central axis A4 that is greater than the height of the support structure 442, such that gas from the canister 436 may 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 may sealingly engage the flange 103 of the syringe to reduce or prevent gas from escaping at the interface of the flange 103 and the support structure 442.

[0105] The housing 410 may define a channel 444 to receive the syringe flange 103 and the support structure 442. The housing 410 may include a partition 446 separating the channel 444 from the orifice 448. The partition 446 may be a protrusion extending inward from the housing body 418. The partition 446 may include an opening so that at least one of the barb 440 and a portion of the tank 436 extends through the opening. The support structure 442 may be slightly compressed between the flange 103 and the partition 446 to prevent accidental damage to the flange 103 or the firing of the injection device 400 before the intended use. In other embodiments, the partition 446 may be positioned between the support structure 442 and the flange 103. In other embodiments, the housing 410 does not include the partition 446, so that the tank 436 and the barb assembly 438 are disposed in the orifice 448. The injection device 400 may include a plenum 420 between the piston 128 and the flange 103 of the syringe 102. When injection device 400 is activated, gas from tank 436 may fill plenum chamber 420. At least a portion of support structure 442 may be positioned in plenum chamber 420.

[0106] 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 tank 436 so that when the tank 436 moves relative to the housing 410, the tank moves the support structure 442. When the support structure is movable relative to the housing 410, the spacer 446 may prevent axial movement of the support structure 442. When the support structure 442 stops moving, the tank 436 may continue to move axially so that there is relative movement between the tank 436 and the support structure 442. The barb 440 may be fixed to the support structure 442 so that the barb 440 is fixed relative to the tank 436 when the support structure 442 is fixed relative to the tank 436, and the barb 440 is movable relative to the tank 436 when the support structure 442 is movable relative to the tank 436.

[0107] The canister 432 may be configured to be in sliding contact with the housing body 418 defining an aperture 448. The aperture 448 may have a width W1 in a plane perpendicular to the central axis A4. The width W1 may be greater than the width W2 of the channel 444. An interference fit may exist between the canister 436 and the sidewalls of the aperture 448 to prevent unintentional movement of the canister 436 prior to use.

[0108] The tank 436 may be capable of being in a ready position ( Figure 4C ) and the joint position ( Figure 4D ) between the canister 436 and the barb 440. The canister 436 may be spaced apart from the barb 440 in the ready position (e.g., axially spaced apart along the axis A4). The canister 436 may be sealed in the ready position. When the canister 436 moves from the ready position to the engaged position, the canister 436 may move relative to the barb 440. The canister 436 may slide in the orifice 448 when moving from the ready position to the engaged position. When the canister 436 moves to the engaged position, the barb 440 may pierce the seal of the canister 436. When the barb 440 pierces the seal, gas may leave the canister 436 to pressurize the plenum chamber and apply an injection force to the piston 128, thereby driving the piston 128 relative to the barrel of the syringe to administer the drug.

[0109] The tank 436 may include an activator 452 (eg, actuated by a user) that can be engaged to move the tank 436 from the ready position to the engaged position. Figure 4B ). The activator 452 may include a first end 454 operatively 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 from the canister 436 along the central axis A4 when the canister 436 is in the ready position. When the activator 452 is moved relative to the housing 410 by a user, the first end 454 may move into contact with the canister 436. The activator may be disposed in an opening in a proximal portion of the housing 410.

[0110] The distal end of the housing body 418 may include a finger flange 408 that can be engaged by a user during use of the injection device 400. For example, the user may engage the finger flange 408 with two fingers while engaging the activator 452 with the thumb. The user may apply a 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 be coupled 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 and Company.

[0111] FIG. 5A to FIG. 5C Another embodiment of an injection device 500 is illustrated. The injection device 500 may include a housing 510 to receive at least a portion of a 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. The barrel 122 may be positionally fixed relative to the housing in at least an axial direction when coupled to the housing 510. The needle guard 522 may be configured to move axially relative to the housing 510 to transition between an injection position and a post-injection position (not shown) in which the distal end of the discharge port 124 extends out of the needle guard 522 ( Figure 5B and Figure 5C ), in which the distal end of the discharge port 124 is retracted into the needle guard 522. In some examples, the housing 510 and the needle guard 522 are part of the UltraSafe Plus injection system sold by Becton, Dickinson and Company.

[0112] The injection device 500 may include a plunger 528 operatively associated with the piston 128 of the syringe 102 to dispense the medicament 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 medicament from the discharge port 124.

[0113] The injection device 500 may include a motive force device 536, which is suitable for applying an injection force to the plunger 528 to administer a drug. 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 can be a magnet, and the other of the first magnetic component 538 and the second magnetic component 540 can be an iron structure to attract the magnet. The first magnetic component 538 can be coupled to the housing 510 near the barrel 122 of the syringe 102. The second magnetic component 540 can be coupled to the plunger 528 at or near the plunger flange 530.

[0114] The distal end of the housing body 518 may include a flange 508 that can be engaged by a user to activate the injection device 500. For example, the user may engage the flange 508 with two fingers while engaging the piston flange 530 with the 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 prime mover 536 may increase as the distance between the first magnetic component 538 and the second magnetic component 540 decreases. The prime mover 536 may provide a force of about 14N to about 100N. In some embodiments, the prime mover 536 applies at least some force before the plunger 528 begins to move. In other embodiments, the prime mover 536 applies the injection force only when the plunger 528 has moved a selected distance. For example, the selected distance may 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 may be spaced apart from each other until the administration of the drug is completed. In some embodiments, when the injection device 500 is in the post-injection configuration, the first magnetic component 538 contacts the second magnetic component 540. In other embodiments, when the injection device 500 is in the post-injection configuration, the first magnetic component 538 is spaced apart from the second magnetic component 540.

[0115] FIG. 6A to FIG. 6CAnother embodiment of an injection device 600 is illustrated, which may include a force applying device for facilitating injection and a load actuator suitable for loading the force applying device. The injection device 600 may include a housing 610 suitable for holding 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 to receive a portion of the syringe 102. The channel 613 may extend through the surface of the lower wall 612 so that the syringe 102 can be loaded into the channel in a transverse direction T, which is perpendicular to each of the lateral direction L and the axial direction A that may be parallel to the central axis A6. The channel 613 may extend from a first side of the lower wall 612 to a second side of the lower wall 612 opposite to the first side in the transverse direction T. The channel 613 may extend through the lower wall 612 so that the syringe 102 can be loaded from the first side or the second side of the lower wall along the transverse direction T. The lower wall 612 may include a groove to fix the syringe 102 in place.

[0116] The injection device may include a plunger 605 adapted to apply an injection force to the piston 128 to dispense a 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 relative to the housing body 618 along the axis A6. 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 relative to the second portion 608 along the axis A6.

[0117] The housing body 618, the lower wall 612, and the upper wall 622 may define a recessed portion to receive a force applying device. The housing 610 may be adapted to receive a biasing element 636. The biasing element 636 may be at least one spring. The biasing element 636 may provide an injection force of about 14N to about 100N. The biasing element 636 may be adapted to apply an injection force to the piston 128. For example, the biasing element 636 may apply an injection force to the flange 604, thereby applying an injection force to the piston 128. The housing body 618 may include a first receiving area 614 and a second receiving area 616 adapted to receive a first biasing element and a second biasing element, respectively. The first receiving area 614 may be spaced apart from the second receiving area in the lateral direction L. The flange 604 may extend at least partially into the channel 620 in each of the first receiving area 614 and the second receiving area 616. Alternatively, the housing body 618 may be a single element that receives each of the first biasing element and the second biasing element or a single biasing element.

[0118] The second portion 608 of the flange 604 can extend into the channel 620 so that the biasing element 636 contacts the second portion 608 during injection. The biasing element 636 can be compressed between the second portion 608 and the housing 610. For example, when the biasing element 636 is in the ready position, the first biasing element can be compressed between the second portion 608 and the upper wall 622 of the first receiving area 614, and the second biasing element can be compressed between the second portion and the upper wall 622 of the second receiving area 616.

[0119] The housing body 618 may include a latch 632 adapted to define a locked position that inhibits movement of the plunger 605 and a released position that enables movement of the plunger 605. The latch 632 may be a protrusion that engages 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 the axis A6 from a first side of the latch 632 to a second side opposite the first side of the latch 632. For example, the latch 632 may be a flexible arm extending from at least one of the first receiving area 614 and the second receiving area 616. The latch 632 may include a protrusion 638 that is engageable with the first portion 606. When the first portion 606 moves relative to the second portion 608, the first portion 606 can contact the protrusion 638 and move the latch 632 out of engagement with the second portion 608, thereby moving the latch 632 from the locked position to the released position. When the latch 632 is in the released position, the biasing element 636 can move the plunger 605 relative to the housing 610. When the plunger 605 moves relative to the housing 610, the second portion 608 of the flange 604 can slide within the channel 620 from the ready position to the fired position.

[0120] refer to FIG. 6A to FIG. 6C and 7A to 7C , the injection device 600 may include a load actuator 640 adapted to load the biasing element 636. The injection device 600 may be adapted to administer a liquid drug when the biasing element 636 is loaded. The load actuator 640 may include an actuator adapted to load at least one biasing element 636 from a firing position ( Figure 7B )Move to the ready position( Fig. 6A and Figure 7C) of the housing body 618. The linkage assembly 642 may include a lever arm 644 coupled to the housing body 618. The lever arm 644 may be capable of pivoting around a pivot 646 fixed to the housing body 618. The lever arm 644 may be configured to rotate around 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 within 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 and a second end 645 opposite the first end 643 and a length as 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.

[0121] The linkage assembly 642 may include at least one linkage arm 648 pivotably coupled to the lever arm 644. The linkage arm 648 may be pivotably coupled to the end of the lever arm 644 such that application of a force to the lever arm 644 transmits a load force upward (i.e., in the axial direction A) through the linkage arm 648 to compress the biasing element 636. The linkage arm 658 may be pivotably coupled to the lever arm 644 at a connection point 650. The connection point 650 may be positioned between the second end 645 and the pivot 646. The pivot 646 may be positioned between the first end 643 and the connection point 650. The second end 645 may be positioned within the housing body 618. Although only one linkage arm is shown, it should be understood that any number of desired linkage arms may be coupled together between the lever arm and the platform 652.

[0122] 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 the axis A6. The platform 652 may move the flange 604 along the axis A6 in response to the rotational movement of the lever arm 644. Although only one linkage arm is shown, it should be understood that any number of desired linkage arms may be coupled together between the lever arm 644 and the platform 652. When the injection device 600 is in the ready position, the lever arm 644 may be in a first position ( Fig. 7A). When the lever arm 644 is in the first position, the platform 652 can be in the lowest position. When the lever arm 644 is in the first position, the spacing between the platform 652 and the flange 604 can be at a maximum distance along the axis A6. When the biasing element 636 expands and the injection device 600 dispenses a dose of the drug, the flange 604 can move toward the platform 652. In some embodiments, when the biasing element 636 expands, the flange 604 moves into contact with the platform 652. In other embodiments, even when the biasing element 636 is fully expanded within the housing 610, the flange 604 remains spaced apart from the platform 652. The lever arm 644 can rotate about the pivot 646 from the first position to the second position ( Figure 7C ). When the lever arm 644 pivots from the first position to the second position, the platform 652 can contact the flange 604. When the lever arm 644 is in the second position, the biasing element 636 can be in its maximum compression state. The lever arm 644 can then rotate back to the first position ( Fig. 7A ), causing the platform 652 to move away from the flange 604, and the injection device is ready to dispense a dose of the drug.

[0123] The linkage assembly 642 may include a pair of linkage arms 648, each positioned within one of the first receiving area 614 and the second receiving area 616. In some embodiments, the biasing element 636 is a pair of springs engaged with opposite ends of the flange 604, and applying force to the lever arm 644 transmits the load force upward through the linkage arm 648 to compress the spring.

[0124] FIG. 8A to FIG. 8B Another embodiment of an injection device 800 is illustrated. The injection device 800 may be similar to the injection device 600, but the injection device 800 does not include a connecting rod assembly. Instead, the flange 604 may be movable relative to the housing 610 from a first position ( Fig. 8A ) is manually moved to the second position ( Figure 8B ). For example, the user may apply a force to the second portion 608 to move the flange 604 relative to the housing 610. Alternatively, the injection device 800 may be a single-use device such that the flange 604 cannot return to the first position.

[0125] 9A to 9E Another embodiment of an injection device 900 is illustrated. 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 to receive at least a portion of a syringe 102. The injection device 900 may include a plunger 926 operatively associated with the piston 128 of the syringe 102 to dispense a medicament from the syringe 102. For example, the plunger 926 may move the piston 128 relative to the barrel 122 of the syringe 102 to dispense a medicament from the discharge port 124.

[0126] The base flange 940 can be coupled to the 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 the syringe 102. The base flange 940 can include a channel 942 so that at least a portion of the syringe 102 can be loaded into the channel 942 in a transverse direction T, which is perpendicular to each of the lateral 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. The rim 944 can be coupled to the body 946 of the base flange 940. The rim 944 can protrude from the 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 may 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 may extend from a surface of the side wall 948 that faces the channel 942. The body 946 may be positioned on a first side of the syringe flange 103, and the top wall 950 may be positioned on a second side of the syringe flange 103 opposite to the first side along the axial direction A. The rim 944 may be sized and dimensioned to mate with the housing body 918. The distal end of the housing body 918 may engage the proximal surface of the body 946. The base flange 940 may be coupled to the housing body 918 by threaded engagement, snap fit, adhesive, or welding.

[0127] The injection device 900 may include a biasing element 936 to move 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 coaxially disposed 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.

[0128] The flange 902 can be similar to 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 extending through an aperture 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 relative to the second portion 906 in an axial direction A.

[0129] The housing 910 may include a latch 912 that can move between a locked configuration in which the movement of the flange 902 is blocked and an unlocked configuration that allows the movement of the flange 902. The latch 912 may be a cantilever beam within an opening in the housing body 918. The latch 912 may include a protrusion extending into the central opening of the housing body 918. When the latch 912 is in the locked configuration, the first protrusion 907 ( Fig. 9C ) can engage the second portion 906 of the flange 902 and prevent movement (e.g., axial movement) of the second portion relative to the housing 910. When the first portion 904 moves relative to the second portion 906 to transition the latch 912 from a locked configuration to an unlocked configuration, the first portion 904 can engage the second protrusion 909. The latch 912 can flex outwardly 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 can each be positioned within a recess defined by the housing body 918.

[0130] The injection device 900 may include a load actuator 941 adapted to load the biasing element 936. The injection device 900 may be adapted to administer a liquid drug when the biasing element 936 is loaded. The load actuator 941 may be similar to the load actuator 640. The load actuator 941 may include a load actuator adapted to load at least one biasing element 936 from a fired configuration ( Fig. 9C ) moves to the preparation construction ( Fig. 9B ) of the connecting rod assembly 962. The connecting rod assembly 962 can be adapted to transmit an axial force to the biasing element 936 in response to rotational movement of the connecting rod assembly 962.

[0131] The linkage assembly 962 may include at least one linkage arm 966 coupled to the lever arm 964. The linkage arm 966 may be coupled to the end of the lever arm 964 such that applying a force to the lever arm 964 transmits a load force (i.e., in the axial direction A) through the linkage arm 966 to compress the biasing element 936. The connecting arm 966 may be fixed to the lever arm 964. The connecting arm 966 may be rotatably fixed to the lever arm 964. The linkage arm 966 and the lever arm 964 may be an integral element. The connecting arm 966 may extend through the opening 911 in the housing body 918 such that the lever arm 964 may be engaged by a user to move the biasing element 936 within the housing 910. Although only one linkage arm is shown, it should be understood that the linkage assembly 962 may include any desired number of linkage arms.

[0132] The link arm 966 may include a first end and a second end opposite the first end along a central axis of the link arm 966. The first end of the link arm 966 may be coupled to the lever arm 964. The second end of the link arm 966 may be pivotally coupled to the flange 902. The second end of the link 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 a central axis of the lever arm. The link arm central axis may be transverse to the lever arm central axis.

[0133] In some embodiments, the second end of the link arm 966 is coupled to the flange 902. In other embodiments, a platform (not shown) may be coupled to the link assembly 962 to move the flange 902 along the axial direction A. The platform may be similar to the platform 652. The flange 604 may move along the axial direction A in response to the rotational movement of the lever arm 964. The lever arm 644 may pivot about the pivot 914. The lever arm 644 may be fixed to the link arm 966 so that both the lever arm 964 and the link arm 966 pivot about the pivot 914. The pivot 914 may be an axle. The pivot 914 may be fixed to the housing 910. The pivot 914 may be located on a first side of the housing 910, and the channel 942 may extend through the outer surface of the base flange 940 on the second side of the housing 910 opposite to the first side. The flange 902 may move from the ready position to the fired position along the axial direction A. The ready position may be proximal to the fired position. The pivot 914 can be axially positioned between the ready position and the fired position.The pivot 914 can be positioned on the outer surface of the housing 910 and positioned along an axis substantially parallel to the central axis of the housing 910 between the ready position and the fired position of the flange 902.

[0134] When the injection device 900 is in the ready configuration, the lever arm 964 may be in the first position ( Fig.9A and Fig. 9B ). When the lever arm 964 is in the first position, the second end of the lever arm 964 can be in a lowermost position. When the lever arm 964 is in the first position, the spacing between the second end of the lever arm 964 and the flange 902 can be at a maximum distance along the axial direction A. When the biasing element 936 expands and the injection device 900 dispenses a dose of the drug, the flange 902 can move toward the second end of the lever arm 964. In some embodiments, when the biasing element 936 expands, the flange 902 moves into contact with the second end of the lever arm 964. In other embodiments, when the lever arm 964 is in the first position and the biasing element 936 is fully expanded within the housing 9010, the flange 902 remains spaced apart from the second end of the lever arm 964.

[0135] The lever arm 964 can be rotated from a first position to a second position ( Fig.9D). When the lever arm 964 pivots from the first position to the second position, the lever arm 964 can contact the flange 902. When the lever arm 964 pivots from the first position to the second position, the lever arm 964 can move the flange 902. When the lever arm 964 is in the second position, the biasing element 936 can be in its maximum compression state. The lever arm 964 can then be rotated back to the first position so that the injection device is ready to dispense a dose of the drug.

[0136] FIG. 10A to FIG. 10J Another embodiment of an injection device 1000 is illustrated. The injection device 1000 can be a power-assisted injection device for administering a liquid drug. The injection device 1000 can 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 can include a cartridge 1002 having a barrel adapted to hold the liquid drug. The cartridge 1002 can include a needle in fluid communication with the barrel such that the medicament is dispensed from the barrel through the needle and to an injection site. The cartridge 1002 can be a syringe 102.

[0137] 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 interior surface and an exterior surface opposite the interior surface. The housing body 1018 may define an interior recess. The housing body 1018 may include a first end and a central axis A. 10 A second end spaced apart from the first end. Central axis A 10 The lateral direction LA may be perpendicular to the longitudinal direction. The transverse direction T may be perpendicular to each of the lateral direction and the longitudinal direction L.

[0138] The housing body 1018 may include a first thread 1020 configured to engage the actuator 1024. The first thread 1020 may be on an interior surface of the housing body 1018. The first thread 1020 may be a helical thread. The first thread 1020 may be positioned in 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.

[0139] 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 so as to create a mechanical advantage relative to the force applied to the actuator 1024 by the user. The second thread 1022 may be positioned in the 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.

[0140] 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. When the actuator 1024 is longitudinally moved via the threaded engagement between the first thread 1020 and the actuator 1024, the actuator 1024 may be movable about the axis A. 10 In some embodiments, the actuator 1024 can engage the first thread 1020 and the second thread 1022 simultaneously. In other embodiments, the actuator 1024 engages the first thread 1020 and the second thread 1022 sequentially.

[0141] 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.

[0142] 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 the first thread 1020. The first member thread 1034 may be positioned on an 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 may extend from the inner surface of the housing body 1018 toward the central axis A. 10 The external thread 1034 may be a helical thread.

[0143] The second member 1030 may include a second member body 1036 having a second member thread 1038 configured to engage the second thread 1022. The second member thread 1038 may be positioned on an outer surface of the second member body 1036. In some embodiments, the second member thread 1038 extends along the longitudinal length of the second member body 1036. In other embodiments, the second member thread 1038 extends 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 mutually rotationally constrained relative 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.

[0144] The shaft 1040 may be fixed 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 the proximal portion of the first member body 1032. The second member 1030 may include a recessed portion 1042 adapted to receive the shaft 1040. The rotation of one of the first member 1028 and the second member 1030 may transfer torque to the other of the first member 1028 and the second member 1030. For example, the shaft 1040 and the recessed portion 1042 may have a non-circular cross-sectional shape taken along a plane perpendicular to the axis A1, so that the rotation of one of the first member 1028 and the second member 1030 transfers torque to the other of the first member 1028 and the second member 1030. The linear movement of the first member 1028 may cause the first member 1028 to rotate via the first thread 1020. The rotation of the first member 1028 can transfer the rotation to the second member 1030 via the shaft 1040 and the recess 1042. The rotation of the second member 1030 can cause the second member 1030 to move linearly relative to the housing body 1018. The second member threads 1038 can have a thread pitch that is different from the pitch of the first member threads 1034. The pitch of the first member threads 1034 can be greater than the pitch of the second member threads 1038, so that the axial translation of the second member 1030 is less than the translation of the first member 1028. The second member 1030 and the first member 1028 can rotate at the same rotation rate, while the first member 1028 translates axially faster than the second member 1030.

[0145] When a user applies a linear force to the actuator 1024, the actuator 1024 may rotate. The user may apply a linear force to a cap 1026 coupled to the actuator 1024. The cap 1026 may be rotatably coupled to the actuator 1024. When the actuator 1024 translates axially relative to the housing body 1018, the cap 1026 may remain rotationally fixed relative to the housing body 1018. When the actuator 1024 rotates relative to the housing body 1018, the cap 1026 may remain rotationally fixed relative to the housing body 1018.

[0146] The injection device 1000 may include a stopper 1044 adapted to apply an injection force to the cartridge 1002. The stopper 1044 may be coupled to the actuator 1024. The stopper 1044 may be coupled to the second member 1030. The stopper 1044 may be coupled to the distal end of the second member 1030. The stopper 1044 may form a fluid seal with the cartridge 1002. In other embodiments, the stopper 1044 may push the piston 128 of the syringe 102. When the actuator 1024 moves relative to the housing body 1018, the stopper 1044 may apply an injection force to dispense a medicament from the cartridge 1002. In some embodiments, the stopper 1044 is rotatably coupled to the second member 1030 so that the stopper 1044 is rotationally fixed relative to the cartridge 1002 when the second member 1030 rotates. In other embodiments, the stopper 1044 is rotatably fixed to the second member 1030. The second member 1030 may have a maximum length in the lateral or transverse direction so that at least a portion of the second member 1030 may enter the barrel of the cartridge 1002 to dispense the medicament ( Fig. 10H In other embodiments, the stopper 1044 comprises a rod-shaped member coupled to the second member 1030 having 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.

[0147] 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 sticking from the needle. 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. After the medicament has been dispensed from the cartridge 1002, the needle guard 1046 may move relative to the housing body 1018. The 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.

[0148] 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 in which the cartridge 1002 is disposed. The needle guard 1046 may at least temporarily engage 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 an edge 1054 of the housing body 1018. For example, the needle guard arm 1052 may include a protrusion 1053 ( Figure 10G ), the protrusion engages the edge 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.

[0149] 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 an inclined surface so that axial movement of the first member 1028 relative to the needle guard arm 1052 causes radial movement of the needle guard arm 1052. When the needle guard arm 1052 moves radially, the needle guard arm 1052 can disengage from the rim 1054 so that the needle guard 1046 can 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.

[0150] When the needle guard 1046 is in the extended position, the needle guard 1046 may 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 may be visible from the exterior of the injection device 1000. For example, when the needle guard 1046 is in the extended position after an injection, a portion of the second member 1030 may be visible through the exterior of the injection device 1000. This may provide a visual indication to the user that the injection is complete and the injection device 1000 is in a locked configuration.

[0151] FIG. 11A to FIG. 11IAnother embodiment of an injection device 1100 is illustrated. The injection device 1100 can be a power-assisted injection device for administering a liquid drug. The injection device 1100 can 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 can be adapted to receive a cartridge 1102 having a barrel adapted to hold the liquid drug. The cartridge 1102 can 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 an injection site. The cartridge 1102 can be a syringe 102. The cartridge 1102 can be fixed relative to the housing 1110. The cartridge 1102 can be fixed longitudinally relative to the housing 1110.

[0152] The injection device 1100 may include a housing 1110 adapted to hold a cartridge 1102. The housing 1110 may include a first end and a central axis A. 11 A second end spaced apart from the first end. Central axis A 11 The lateral direction LA may be perpendicular to the longitudinal direction L. The transverse direction T may be perpendicular to each of the lateral direction and the longitudinal direction L.

[0153] 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 each other. The housing 1110 may include a housing 1108. The upper body 1112 may be movable relative to the housing 1108. The lower body 1114 may be movable relative to the housing 1108. The upper body 1112 and the lower body 1114 may be movable relative to the housing 1108. The upper body 1112 and the lower body 1114 may be movable relative to the housing 1108 in a longitudinal direction L. The finger flange 1106 may extend from the housing 1108.

[0154] One of the upper body 1112 and the lower body 1114 may be telescopically nested within the other of the upper body 1112 and the lower body 1114. The pinion assembly 1116 may be coupled to at least one of the upper body 1112 and the lower body 1114. The pinion assembly 1116 may include a pinion pair coupled to the shaft 1122. The pinion pair may include a first pinion 1118 and a second pinion 1120. The first pinion 1118 and the second pinion 1120 may be coaxial. The first pinion 1118 and the second pinion 1120 may each be adapted to rotate around a central axis of the shaft 1122. The first pinion 1118 and the second pinion 1120 may be coupled to the same shaft 1122. The pinion assembly 1116 may be axially fixed relative to the housing 1110 in a longitudinal direction. 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 housing 1108 .

[0155] The upper body 1112 may be adapted to engage the first pinion gear 1118. The upper body 1112 may include an upper rack 1124 adapted to engage teeth of the first pinion gear 1118. The upper rack 1124 and the first pinion gear 1118 may have a first gear pitch.

[0156] The lower body 1114 may be adapted to engage the second pinion 1120. The lower body 1114 may include a lower rack 1126 adapted to engage the teeth of the second pinion 1120. The lower rack 1126 and the second pinion 1120 may have a second gear pitch. The first gear pitch may be different from the second gear pitch. The first gear pitch may be greater 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 mm in response to the upper body 1112 moving 1 mm relative to the housing 1110.

[0157] The injection force may be applied to the upper body 1112. For example, the user may manually apply an axial force to the proximal end 1115 of the upper body 1112 using a thumb or finger. The upper body 1112 may 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 may extend from the end wall 1128. The beam 1130 may be a cantilever beam. The beam 1130 may extend from a first end to a second end opposite to the first end in a longitudinal direction L along a central axis. The first end of the beam 1130 may be coupled to the end wall 1128. The second end of the beam 1130 may be a free end. Spacing 1129 may separate the beams 1130 from each other. The beams 1130 may be spaced circumferentially from each other. At least one beam 1130 may include an 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 1118. The shaft 1122 can be positioned in at least one of the spacings 1129 between the beams 1130.

[0158] The housing 1110 may include guides to at least partially maintain the alignment of the beams 1130 relative to each other. In some embodiments, the guides may be protrusions extending from the interior surface of the housing 1108 into the spacing 1129 between the beams. In other embodiments, the guides are recesses in the sidewalls of the housing 1110 that receive the beams 1130.

[0159] The lower body 1114 may be adapted to apply an injection force to the plunger 1104. The lower body 1114 may include an end wall 1132 operatively associated with the plunger 1104 such that the lower body 1114 applies an injection force to the plunger 1104. For example, the plunger 1104 may be coupled to the end wall 1132. In some embodiments, the plunger 1104 and the lower body 1114 are integrally constructed. In other embodiments, the plunger 1104 and the lower body 1114 are separate elements operatively associated with each other. One or more lower body beams 1134 may extend from the end wall 1132. The lower body beam 1134 may be a cantilever beam. The lower body beam 1134 may 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 may be coupled to the lower body end wall 1132. The second end of the lower body beam 1134 may be a free end. A spacing 1136 may separate the lower body beams 1134 from each other. The lower body beams 1134 may be spaced apart from each other around the perimeter of the lower body 1114. An annular connector may couple the second ends of the lower body beams 1134 to each other.

[0160] At least one lower body beam 1134 may include a lower rack 1126. The shaft 1122 may be positioned in at least one of the spacings 1136 between the lower body beams 1134. The first pinion 1118 may be positioned in at least one of the spacings 1136. The outer surface of the lower body 1114 may be laterally spaced apart from the inner surface of the upper body 1112.

[0161] When the injection device 1100 is in the ready configuration ( Fig.11D ), 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. At the moment during injection ( Fig.11E ), 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. When the injection device 1100 is in the firing configuration ( Fig.11F ), the distal end 1140 of the lower body beam 1134 may be positioned proximal to the distal end 1142 of the upper body beam 1130. At least one of the upper body 1112 and the housing 1108 may include a locking feature. The locking feature may be a protrusion on one of the upper body 1112 and the housing 1108 that is received in a recess on the other of the upper body 1112 and the housing 1108 to lock the injection device in the firing configuration.

[0162] The tip 1138 may be engaged with the housing 1110. The tip 1138 may be removably coupled to the housing 1110. The tip 1138 may be coupled to the distal end of the housing 1110. The tip 1138 may be coupled to the housing 1108 of the housing 1110. The tip 1138 may be configured to engage the cartridge 1102. The tip 1138 may include an extension 1144 adapted to receive the cartridge 1102. The end surface of the extension 1144 may be adapted to engage the flange 1103 on the cartridge 1102. When the tip 1138 is coupled to the housing 1110, the extension 1144 may be positioned within the housing 1110. The cartridge 1102 may 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 cantilever beams. The beam 1146 may extend from a first end to a second end opposite the first end along the central axis in a longitudinal direction L. The first end of the beam 1146 may be coupled to the body of the tip 1138. The second end of the beam 1146 may be a free end. The spacing 1129 may separate the beams 1146 from each other. The beams 1146 may be circumferentially spaced from each other. The beams 1146 may be aligned with the beams 1130 around the inner periphery of the housing 1108. The beams 1134 of the lower body 1114 may fit into the spacing between the beams 1146.

[0163] The injection device 1100 can be reusable. For example, the tip 1138 can be removed from the housing 1110 after injection, a new cartridge 1102 can be loaded into the tip 1138, and the tip 1138 can be reconnected to the housing 1110. The 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 longitudinally opposite to the injection force direction. Alternatively, when the tip 1138 is removed from the housing 1110, the user can apply a reload force to the plunger 1104 to move the upper body 1112 and the lower body 1114 to the pre-injection configuration.

[0164] FIG. 12A to FIG. 12B Another embodiment of an injection device 1200 is illustrated. The injection device 1200 may be a power-assisted injection device for administering a liquid medication. 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 may include a first end and a central axis A. 12 A second end spaced apart from the first end. Central axis A 12 may extend in the longitudinal direction L. The lateral direction LA may be perpendicular to the longitudinal direction L. The transverse direction T may be perpendicular to each of the lateral direction LA and the longitudinal direction L. The housing may include a finger flange 1208 engageable by a user during an injection.

[0165] 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 translated 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, when the injection device 1200 is in the post-injection configuration, the upper body 1212 extends from the proximal end of the lower body 1214. 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, line, cord, 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. The tether 1216 may be coupled to the distal end of the upper body 1212. The tether 1216 may be coupled to the distal end of the lower body 1214. When the injection device 1200 is in the post-injection configuration ( Fig. 12B ), the distal end of the upper body 1212 can be joined to the distal end of the lower body 1214.

[0166] The plunger 1204 may be movable relative to the syringe 102. When the plunger 1204 moves relative to the syringe 102, the plunger 1204 is adapted to dispense liquid medication from the barrel of the syringe 102. The plunger 1204 may include a pulley assembly 1218. The pulley assembly 1218 may include a pulley wheel. The tether 1216 may engage the pulley wheel. The pulley assembly 1218 may be positioned proximal to the distal portion of each of the upper body 1212 and the lower body 1214. The plunger 1204 may be movable relative to each of the upper body 1212 and the lower body 1214.

[0167] The upper body 1212 can move relative to the lower body 1214 in response to applying a force to the upper body 1212. For example, a user can engage the finger flange 1208 with their fingers and apply a linear force to the upper body 1212 with their thumb. The movement of the upper body 1212 relative to the lower body 1214 can induce tension in the tether 1216. The tension in the tether can apply an injection force on the plunger 1204 via the pulley wheel. The injection device 1200 can provide a mechanical advantage of increasing the injection force compared to the linear force applied by the user. The injection force on the pulley wheel can be twice the linear force because the two ends of the line act cooperatively and each end applies a linear force equal to the linear force. The upper body 1212 can move longitudinally a first amount relative to the lower body 1214. The plunger 1204 can move longitudinally a second amount relative to the lower body 1214. The first amount can be greater than the second amount.

[0168] Fig. 12C Illustrate the principle of the mechanical advantage provided by a pulley.A wire tensioned with a force of 50N provides a force of 100N to the pulley.

[0169] The injection device 1200 may be reusable. The user may detach the upper body from the lower body 1214. The syringe 102 may be removed from the housing 1210 and replaced. The upper body 1212 may then be coupled to the lower body 1214 such that the injection device 1200 is ready for use.

[0170] FIG. 13A to FIG. 13F Another embodiment of an injection device 1300 is illustrated. The injection device 1300 may be a power-assisted injection device for administering a liquid drug. The injection device 1300 may be in a ready configuration ( FIG. 13A to FIG. 13B )、First firing structure ( FIG. 13C to FIG. 13D ) and the second firing structure ( FIG. 13E to FIG. 13F ). The injection device 1300 may be adapted to provide a variable injection force during an injection. For example, the injection device 1300 may provide a first injection force during a first stage of an injection and a second injection force during a second stage of an injection. The second force may be greater than the first force.

[0171] The injection device 1300 may include a housing 1310 having a housing body 1312 adapted to receive the syringe 102. The housing 1310 may include a first end and a central axis A. 13 A second end spaced apart from the first end. Central axis A 13 The plunger 1304 may extend in the longitudinal direction L. The lateral direction LA may be perpendicular to the longitudinal direction L. The transverse direction T may be perpendicular to each of the lateral 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 to dispense the medicament from the needle connected to the syringe. The plunger 1304 may form a liquid seal with the side wall of the barrel.

[0172] 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 spaced apart from each other and moved into engagement during injection. The inner frame 1320 may be adapted to receive a power source to move the inner frame 1320 relative to the housing body 1312. The inner frame 1320 may include a side wall 1322 defining a channel 1324 to receive a motive force device.

[0173] The inner frame 1320 may be adapted to receive a first flange 1318. The first flange 1318 may extend across a lateral width of the inner frame 1320. The first flange 1318 may divide a channel 1324 of the inner frame 1320 into a first channel and a second channel. The first flange 1318 may be movable relative to the inner frame 1320. The first flange 1318 may be longitudinally movable relative to the inner frame 1320. The inner frame 1320 may be longitudinally translated relative to the housing body 1312 while the first flange 1318 remains longitudinally fixed relative to the housing body 1312.

[0174] End wall 1321 may be coupled to inner frame 1320. End wall 1321 may be fixed to inner frame 1320 such that end wall 1321 moves with inner frame 1320 relative to housing body 1312. End wall 1321 may be fixed to side wall 1322. End wall 1321, side wall 1322, and plunger 1304 may be an integral construction.

[0175] The injection device 1300 may include a latch 1306 adapted to define a locked position that inhibits movement of the plunger 1304 and a released position that enables 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 ) moves to the unlocked position ( Fig. 13C). The latch 1306 can be a cantilever beam extending from the housing body 1312. The latch 1306 can bend relative to the housing body 1312 from a locked position to an unlocked position. The latch 1306 can bend laterally outward relative to the housing body 1312 from a locked position to an unlocked position.

[0176] The injection device 1300 may include a device that can be in an extended position ( Fig.13A ) and retracted position ( Fig. 13C ) between the housing 1310 and the injection device 1300. 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 enclose at least a portion of the syringe 102 in the extended position. When the needle guard 1350 is in the extended position, the needle guard 1350 may extend distally beyond the distal end of the needle. At least a portion of the needle guard 1350 may extend into the housing 1310. Movement of the needle guard 1350 may be configured to activate the injection device 1300. When the needle guard 1350 moves from the extended position to the retracted position, the proximal end (not shown) of the needle guard 1350 may move the latch 1306.

[0177] The latch 1306 may include a first tooth 1326 adapted to engage the first flange 1318. When the latch 1306 is in the locked position, the first tooth 1326 may prevent the first flange 1318 from moving distally in the longitudinal direction relative to the housing body 1312. 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.

[0178] 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 so that axial movement of the second flange 1316 relative to the second tooth 1328 causes the latch 1306 to move laterally outward.

[0179] When the second flange 1316 begins to engage the second tooth 1328, the first flange 1318 can engage the first tooth 1326. When the latch 1306 moves to the release position, the first flange 1318 can disengage from the first tooth 1326. The radially lateral outward movement of the latch 1306 can allow the first flange 1318 to disengage from the first tooth 1326.

[0180] The injection device 1300 may include a first latch, and the latch 1306 may be a second latch. The first latch may be capable of moving from a locked position to an unlocked position. Movement of the first latch may engage actuation of the first power source 1338 to initiate an injection. When the latch 1306 is in the locked position, movement of the first latch may allow the inner frame 1320 to move relative to the housing body 1312.

[0181] 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 drug when the latch 1306 is released 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 in a first portion of the channel 1324, and the second power source 1340 may be positioned in a second portion of the cavity, wherein the first flange 1318 separates the first portion and the second portion of the cavity.

[0182] The first power source 1338 may be in compression between the first flange 1318 and the end wall 1321. The second power source 1340 may be in compression between the first flange 1318 and the housing body 1312. The second power source 1340 may apply a greater force than the force applied by the first power source 1338. The second power source 1340 applies a greater force to overcome any pressure at the injection site due to the drug that has been delivered to the injection site.

[0183] The first power source 1338 may provide a first injection force during the first stage of injection. The second power source 1340 may provide a second injection force during the second stage of injection. The first power source 1338 and the second power source 1340 may each be a spring. The first power source 1338 and the second power source 1340 may be arranged in series so that the first power source 1338 provides the injection force during the first stage of injection and the second power source 1340 provides the injection force during the second stage of injection. In other embodiments, the first power source 1338 may provide power during the first stage of injection, and both the first power source 1338 and the second power source 1340 contribute to the injection force during the second stage of injection. In other embodiments, the first stage overlaps with the second stage so that the first power source 1338 applies the injection force, then both the first power source 1338 and the second power source 1340 apply the injection force, and then the second power source 1340 independently applies the injection force. The first power source 1338 and the second power source 1340 may be adapted to be actuated at least partially in series. For example, the injection force provided by each of the first power source 1338 and the second power source 1340 may not be applied at exactly the same time.

[0184] The first stage of injection may begin when the plunger 1304 begins to move relative to the housing body 1312. The second stage of injection may begin when the second flange 1316 engages the second tooth 1328 and transitions the latch 1306 to the released position. The first flange 1318 may be fixed relative to the housing body 1312 during the first stage and movable in a longitudinal direction relative to the housing body 1312 during the second stage.

[0185] The second flange 1316 can engage the latch 1306 to lock the inner frame 1320 in the second position after injection. The second flange 1316 can move distally in the longitudinal direction L during injection so 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 can be adapted to move toward the central axis A after the second flange 1316 moves past the first tooth 1326. 13 The 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, thereby locking the inner frame 1320 in the second position.

[0186] It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the broad inventive concept of the present invention. In addition, it will be appreciated that the above structures, features and methods, as relative to any of the embodiments described herein, may be incorporated into any other embodiments described herein unless otherwise indicated. Therefore, it will be appreciated that the present invention is not limited to the specific embodiments disclosed, but is intended to cover modifications within the spirit and scope of the present disclosure. In addition, it will be appreciated that the term substantially indicates that certain directional components are not completely perpendicular to each other, and substantially perpendicular means that the direction has a main directional component perpendicular to another direction.

Claims

1. A power-assisted injection device for administering a liquid drug, the injection device comprising: a syringe comprising a plunger and a barrel adapted to hold the liquid medication; a housing including a body adapted to hold the syringe and a latch configured to define a locked position inhibiting movement of the plunger and a released position enabling 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; and a motive device coupled to the second end of the housing, the motive device being configured to apply an injection force to the plunger to administer the medicament when the latch is in the released position; The injection device is thereby configured for administering the liquid drug at least partially via the motive force means applying the injection force to the plunger of the syringe when the latch is released from the locked position.

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

3. The injection device of claim 2, wherein the housing comprises 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. The injection device of claim 3, wherein the housing includes a base proximate an upper portion of the barrel of the syringe, the at least one spring of the motive means being a pair of springs in tension between the housing base and the housing flange.

5. An injection device according to claim 4, wherein the latch is a protrusion in the housing, which contacts the underside of the housing flange when the latch is in the locked position, thereby retaining the housing flange in the locked position until released.

6. A power-assisted injection device for administering a liquid drug, the injection device comprising: a syringe comprising a plunger and a barrel adapted to hold the liquid medication; a housing including a body adapted to retain the syringe and a latch configured to define a locked position inhibiting movement of the plunger and a released position enabling movement of the plunger; and a motive force device configured to apply an injection force to the plunger to administer the drug when the latch is in the released position; wherein the injection device is configured to administer the liquid drug at least in part via the motive force means applying the injection force to the plunger of the syringe when the latch is released from the locked position, The motive force device is a spring coaxial with the plunger.

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. An injection device according to claim 7, wherein the spring is in tension between the base structure and the flange when the latch is in the locked position.

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

10. The injection device of claim 3, wherein the housing includes a base proximate an upper portion of the housing body, the at least one spring of the motive means being a pair of springs in compression between the housing base and the housing flange when the latch is in the locked position.

11. An injection device according to claim 10, wherein the latch is a protrusion in the housing, which contacts the underside of the housing flange when the latch is in the locked position, thereby retaining the housing flange in the locked position until released.

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

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

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

15. The injection device of claim 13, wherein said magnets are spaced apart until said administration of said drug is complete.

16. A power-assisted injection device for administering a liquid drug, the injection device comprising: a syringe comprising a plunger and a barrel adapted to hold the liquid medication; a housing including a body adapted to retain the syringe and a latch configured to define a locked position inhibiting movement of the plunger and a released position enabling movement of the plunger; and a motive force device configured to apply an injection force to the plunger to administer the drug when the latch is in the released position; whereby the injection device is configured for administering the liquid drug at least in part via the motive force means applying the injection force to the plunger of the syringe when the latch is released from the locked position, Wherein the motive means is a first spring and a second spring, the first spring and the second spring being configured for at least partially serial actuation.

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

18. The injection device of claim 17, wherein the latch is a first latch and a second latch, wherein release of the first latch engages actuation of the first spring and release of the second latch engages actuation of the second spring.

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 partition, wherein upon release of the first latch and prior to release of the second latch, the first spring moves from a compressed position to an extended position, and upon release of the second latch, the second spring moves from a compressed position to an extended position.

20. An injection device according to any one of the preceding claims, wherein the translatable housing flange comprises a contact portion configured for contact by a user to move the housing flange upwardly to reset the motive force means.

21. A power-assisted injection device for administering a liquid drug, the injection device comprising: a syringe comprising a plunger and a barrel configured to hold the liquid drug; at least one spring configured to apply an injection force to the plunger to administer the drug; 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 to apply the injection force to the syringe; and a loading actuator configured to load the spring; The injection device is thereby configured for administering the liquid drug when the spring is loaded.

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

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

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

25. An injection device according to claim 23, wherein (i) the linkage assembly further comprises a linkage arm pivotally coupled to an inner end of the lever arm, (ii) the at least one spring is a pair of springs engaged with opposite ends of the housing flange, and (iii) the at least one linkage arm is a pair of linkage arms engaged with opposite ends of the housing flange, whereby applying a force to the lever arm transmits a load force upward through the linkage arm to compress the spring.

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

27. The injection device of claim 21, wherein the housing includes a removable base flange configured for engaging the syringe, the base flange being located at a distal portion of the housing base.

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

29. An injection device according to claim 28, wherein the housing comprises an aperture slidably contactable with the gas canister, whereby the gas canister slides in the aperture when moving from the ready position to the engaged position.

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

31. A power-assisted injection device for administering a liquid medication, the injection device comprising: a container comprising a barrel configured to hold the liquid drug and a stopper configured to seal the barrel, the stopper being movable relative to the container to apply an injection force to the liquid drug in the barrel; a housing comprising a body configured to hold the container, a first housing helical thread on an interior surface of the body defining a first pitch, a second housing helical gear thread on the interior surface of the body defining a second pitch; and An actuator is configured to engage the first housing helical thread and the second housing helical thread and to apply the injection force to the stopper.

32. An injection device according to claim 31, wherein the actuator comprises a first member and a second member, the first member and the second member being configured to rotate relative to each other when a user applies a linear force to the actuator, the first member gear having a pitch different from a pitch of the second member to create a mechanical advantage relative to the force applied by the user to the actuator.

33. The injection device of claim 31 , wherein the actuator comprises a first member and a second member, The first member gear includes a first member body and threads on an exterior surface of the first member body, the threads being configured to engage the first housing body helical gear threads, The second member includes a second member body and threads on an exterior surface of the second member body, the threads being configured to engage the second housing body helical gear threads, wherein the first member and the second member are rotationally constrained relative to each other, wherein rotation of one of the first member and the second member transmits torque to the other of the first member and the second member, and Wherein the second member has a pitch different from the pitch of the first member.

34. The injection device of claim 31 , wherein the actuator comprises a first member and a second member, The first member includes a first member body, a shaft fixed to and extending coaxially from the first member body, and threads on an exterior surface of the first member body, the threads having the first pitch, the first member threads being configured to engage the first housing body helical gear threads, The second member includes a second member body, a recessed portion configured to receive the shaft of the first member and rotationally constrained to the shaft, and threads on an exterior surface of the second member body having the second pitch, the second member threads configured to engage the second housing body helical gear threads, wherein a linear force applied to the first member rotates the first member via engagement with the first inner and outer shell threads, the rotation of the first member transmits the rotation to the second member via the shaft and the recessed portion, the first pitch of the first member is greater than the second pitch of the second member, so that the second member has a translation that is less than the translation of the first member.

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

36. An injection device according to claim 35, wherein the housing comprises a removable tip engaged with the housing lower body, the removable tip engaging the container and enabling its replacement.

37. A power-assisted injection device for administering a liquid medication, the injection device comprising: a syringe comprising a plunger and a barrel configured to hold the liquid drug; a housing comprising a lower body and an upper body movable relative to the lower body; and 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 thereby generates tension in the tether, thereby generating an injection force on the plunger via the pulley wheel.

38. An injection device according to claim 37, wherein the lower body comprises a flange configured to engage a finger of a user.

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

40. The injection device of claim 37, wherein the tether is any one of a wire, a rope, a belt.

41. An injection device according to any preceding claim, further comprising a passive needle guard.

42. The injection device of claim 1, wherein the liquid drug has a viscosity of at least 10 centipoise at 20 degrees Celsius.

43. The injection device of claim 1, wherein the housing defines a recess extending from the first end toward the second end, the plunger being disposed within the recess and configured to move in a distal direction toward the second end to administer the drug.

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

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