Patent Description:
It is desirable to be able to administer injections simply and safely when treating a patient. A conventional syringe for administering injections includes a barrel for holding medicament, a plunger that fits within the barrel and a needle through which the medicament is expelled when the plunger is pushed inside the barrel. Typically, the syringe will have a cap for shielding the needle when the syringe is not being used to administer an injection, which can be removed in order to expose the needle.

A specific problem with a conventional syringe is that a patient might accidentally stick themselves, or someone else, with the needle before administering the injection. Another specific problem is that it can be difficult to align the needle with the target site correctly, and thus an injection might be administered in the wrong place. Therefore, conventional syringes can be complicated and potentially unsafe to use, particularly for patients with limited dexterity.

Injection devices exist that have been designed to overcome these issues with conventional syringes. One such device includes a needle shield and a plunger which can be actuated in order to force medicament from the needle and into the patient. The needle shield retracts when pressed against the target site in order to expose the needle, and the plunger can be pressed at the same time for administering the injection. This allows the injection to be administered in a single motion by pressing the plunger of the device down onto the target site. This allows a patient to administer themselves with an injection in a safe and simple manner. Often these devices are designed so that they can be used only once, for instance by locking the needle shield in a position that covers the needle once the injection is complete. This prevents a patient from using a needle more than once, which has hygiene and health benefits.

An issue with known injections devices is that it can be difficult to train a patient on the use of these devices without actually administering an injection. Therefore, proper training may be limited to times when an injection is required. Alternatively, a non-active ingredient could be used as the substance for injection during training. However, unnecessarily injecting people should be avoided for health and hygiene reasons.

In light of the above, there is a need for a device that can be used to train a patient to use an injection device in a simple and safe manner. In addition, it is desirable for such a device to be used multiple times, so that multiple instances of training can be conducted using the same device. There is also a need for an injection device that has a simple construction and operates in a reliable manner.

In <CIT> there is described a syringe holder including a barrel body that holds a syringe, a holder opening, deformation promoting portions, and radial movement-restricting portions.

In <CIT> there is described a device for injection of a medicament including a housing having distal and proximal end openings; a needle guard extending from the proximal end opening and movable relative to the housing from an extended position to a retracted position, in which the needle guard is biassed toward the extended position; an activation member extending from the distal end opening and movable relative to the housing from an initial position to a final position; a lock that restricts movement of the activation member in the final position; and a needle guard lock that restricts movement of the needle guard from the extended position to the retracted position when the activation member is in the final position.

In <CIT> there is described a reusable drug delivery device for selecting and dispensing a number of user variable doses of a medicament.

In <CIT> there is described a medicament delivery device comprising a housing, which housing is arranged to accommodate a medicament container, a drive unit operably arranged to act on said medicament container for expelling a dose of medicament, the drive unit comprising a plunger rod, a force element operably connected to said plunger rod, a connector arranged to releasibly hold said plunger rod, an actuator element operably arranged to said connector and a manually operable actuator arranged to act on said actuator element for releasing said connector when operated.

In one aspect of the invention, there is an injection device trainer for training a user to use an injection device, the injection device trainer comprising a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position; a retracted position that is more proximal relative to the body portion than the initial position; and an extended position that is more distal relative to the body portion than the initial position, and a locking member rotatable between a first orientation in which the locking member resists movement of the actuator from the proximal position to the distal position; and a second orientation in which the locking member permits
the actuator to move from the proximal position to the distal position. The first orientation of the locking member is configured to hold the shield in the initial position such that the shield is prevented from moving from the initial position to the extended position, and permits movement of the shield from the initial position to the retracted position. The shield is configured to contact with the locking member when moving from the initial position to the retracted position in order to move the locking member from the first orientation to the second orientation. Movement of the actuator by a first distance towards the distal position unlocks the shield from the locking member such that the shield is allowed to move towards the extended position.

Therefore, the injection device trainer accurately simulates use of an injection device which improves the training process. In addition, the user can practice administering an injection more times than in comparison to the situation in which training is only possible when a real injection is required. The locking member provides a mechanism for simulating use of the injection device.

In another aspect of the invention, there is an injection device comprising, a needle coupled with a chamber for storing fluid, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position in which the shield covers the needle; a retracted position in which the shield exposes the needle, wherein the retracted position is more proximal relative to the body portion than the initial position; and an extended position in which the shield covers the needle, wherein the extended position is more distal relative to the body portion than the initial position, and a locking member rotatable between a first orientation in which the locking member resists movement of the actuator from the proximal position to the distal position; and a second orientation in which the locking member permits the actuator to move from the proximal position to the distal position. The first orientation of the locking member is configured to hold the shield in the initial position such that the shield is prevented from moving from the initial position to the extended position, and permits movement of the shield from the initial position to the retracted position. The shield is configured to contact the locking member when moving from the initial position to the retracted position in order to move the locking member from the first orientation to the second orientation. Movement of the actuator by a first distance towards the distal position unlocks the shield from the locking member such that the shield is allowed to move towards the extended position.

This provides a construction for the injection device that assists with reliability and ease of manufacture.

In another aspect of the invention, there is a method for training a user to use an injection device, the method comprising providing an injection device trainer comprising, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position; a retracted position that is more proximal relative to the body portion than the initial position; and an extended position that is more distal relative to the body portion than the initial position, and a locking member rotatable between a first orientation in which the locking member resists movement of the actuator from the proximal position to the distal position; and a second orientation in which the locking member permits the actuator to move from the proximal position to the distal position. The first orientation of the locking member is configured to hold the shield in the initial position such that the shield is prevented from moving from the initial position to the extended position, and permits movement of the shield from the initial position to the retracted position. The method further comprises moving the shield from the initial position to the retracted position so that the shield contacts with the locking member in order to move the locking member from the first orientation to the second orientation, and moving the actuator by a first distance towards the distal position to unlock the shield from the locking member such that the shield moves towards the extended position.

In another aspect of the invention, there is a method of administering an injection, the method comprising providing an injection device comprising, a needle coupled with a chamber for storing fluid, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position in which the shield covers the needle; a retracted position in which the shield exposes the needle, wherein the retracted position is more proximal relative to the body portion than the initial position; and an extended position in which the shield covers the needle, wherein the extended position is more distal relative to the body portion than the initial position, and a locking member rotatable between a first orientation in which the locking member resists movement of the actuator from the proximal position to the distal position; and a second orientation in which the locking member permits the actuator to move from the proximal position to the distal position. The first orientation of the locking member is configured to hold the shield in the initial position such that the shield is prevented from moving from the initial position to the extended position, and permits movement of the shield from the initial position to the retracted position. The method further comprises moving the shield from the initial position to the retracted position so that the shield contacts the locking member in order to move the locking member from the first orientation to the second orientation, and moving the actuator by a first distance towards the distal position to unlock the shield from the locking member such that the shield moves towards the extended position.

According to the invention, there is provided an injection device trainer for training a userto use an injection device, the injection device trainer comprising, a body portion and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position. The body portion comprises a body protrusion and the actuator comprises a latch that is arranged to couple with the body protrusion when the actuator is in the distal position, thus holding the actuator in the distal position.

In this way, coupling of the latch to the body protrusion indicates that the actuator has reached the distal position which simulates completion of an injection being administering by an injection device. Therefore, the user can be trained to determine that an injection has been administered properly.

According to the invention, there is provided an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle. The body portion comprises a body protrusion and the actuator comprises a latch that is arranged to couple with the body protrusion when the actuator is in the distal position, thus holding the actuator in the distal position.

In this way, coupling of the latch to the body protrusion indicates that the actuator has reached the distal position which indicates completion of an injection being administering by the injection device. Therefore, the user can more accurately determine that the injection has been administered properly.

In another aspect of the invention, there is provided an injection device trainer for training a user to use an injection device, the injection device trainer comprising a body portion and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position. The body portion comprises a body protrusion and the actuator comprises a latch that is arranged to contact the body protrusion when the actuator is in the distal position and to emit an audible sound.

In this way, the audible sound indicates that the actuator has reached the distal position which simulates completion of an injection being administering by an injection device. Therefore, the user can be trained to determine that an injection has been administered properly. The audible sound may have an intensity that enables a user to hear the sound at <NUM> away from the device, or at least at an arm's length from the device. The latch may be configured to emit an audible sound above a predetermined threshold intensity at a certain distance from the device (e.g. <NUM>). For example, the predetermined threshold intensity may be <NUM> dB, such that the intensity of the sound emitted is above the normal sound intensity of a quiet room. This enables the user to hear the sound in a normal working environment. The predetermined threshold intensity may be <NUM> dB, <NUM> dB or even <NUM> dB in order to ensure that the user can hear the sound in a variety of different environments. The sound may be in the form of a 'click', which is a short sound (e.g. less than a second long). The sound is emitted due to the mechanical interaction between the latch and the body protrusion, and is not emitted by an electronic device.

In another aspect of the invention, there is provided an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing the fluid stored in the chamber from the needle. The body portion comprises a body protrusion and the actuator comprises a latch that is arranged to contact the body protrusion when the actuator is in the distal position and to emit an audible sound.

In this way, the audible sound indicates that the actuator has reached the distal position which indicates completion of an injection being administering by the injection device. Therefore, the user can more accurately determine that the injection has been administered properly.

According to the invention, there is a method for training a user to use an injection device, the method comprising providing an injection device trainer comprising a body portion and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position. The body portion comprises a body protrusion and the actuator comprises a latch. The method further comprises moving the actuator from the proximal position to the distal position so that the latch couples with the body protrusion when the actuator is in the distal position, thus holding the actuator in the distal position.

In another aspect of the invention, there is a method of administering an injection, the method comprising providing an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle. The body portion comprises a body protrusion and the actuator comprises a latch. The method further comprises moving the actuator from the proximal position to the distal position so that the latch couples with the body protrusion when the actuator is in the distal position, thus holding the actuator in the distal position.

In another aspect of the invention, there is a method for training a user to use an injection device, the method comprising providing an injection device trainer comprising a body portion and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position. The body portion comprises a body protrusion and the actuator comprises a latch. The method further comprises moving the actuator from the proximal position to the distal position so that the latch contacts the body protrusion when the actuator is in the distal position and emits an audible sound.

In another aspect of the invention, there is a method of administering an injection, the method comprising providing an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, and an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing the fluid stored in the chamber from the needle. The body portion comprises a body protrusion and the actuator comprises a latch. The method further comprises moving the actuator from the proximal position to the distal position so that the latch contacts the body protrusion when the actuator is in the distal position and emits an audible sound.

In another aspect of the invention, there is an injection device trainer for training a user to use an injection device, the injection device trainer comprising a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position; an extended position that is more distal relative to the body portion than the initial position, and a connector that connects the actuator to the shield such that movement of the actuator from the distal position towards the proximal position pulls the shield from the extended position to the initial position.

In this way, it is possible to reset the injection device trainer back to the initial position such that the trainer can be used again. The connector provides a mechanism for achieving this function.

In another aspect of the invention, there is an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position in which the shield covers the needle; a retracted position in which the shield exposes the needle, wherein the retracted position is more proximal relative to the body portion than the initial position; and an extended position in which the shield covers the needle wherein the extended position is more distal relative to the body portion than the initial position, and a connector that connects the actuator to the shield such that movement of the actuator from the distal position towards the proximal position pulls the shield from the extended position to the initial position.

In this way, it is possible to reset the injection device back to the initial position such that the injection device can be used more than once. The connector provides a mechanism for achieving this function.

In another aspect of the invention, there is a method for training a user to use an injection device, the method comprising providing an injection device trainer comprising, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position; an extended position that is more distal relative to the body portion than the initial position, and a connector that connects the actuator to the shield. The method further comprises moving the actuator from the distal position towards the proximal position in order to pull the shield from the extended position to the initial position using the connector.

In another aspect of the invention, there is a method of administering an injection, the method comprising providing an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, an actuator positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing fluid stored in the chamber from the needle, a shield positioned towards a distal end of the body portion, the shield moveable between: an initial position in which the shield covers the needle; a retracted position in which the shield exposes the needle, wherein the retracted position is more proximal relative to the body portion than the initial position; and an extended position in which the shield covers the needle wherein the extended position is more distal relative to the body portion than the initial position, and a connector that connects the actuator to the shield. The method further comprises moving the actuator from the distal position towards the proximal position in order to pull the shield from the extended position to the initial position using the connector.

In another aspect of the invention, there is an injection device trainer for training a user to use an injection device, the injection device trainer comprising a body portion an actuator assembly positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, wherein the actuator assembly is coupled with a rotor, such that movement of actuator from the proximal position to the distal position causes the rotor to rotate, and a damping element coupled, or coupleable, to the rotor in order to damp the rotation of the rotor.

In this way, it is possible for the injection device trainer to simulate the resistance provided by the medicament in the injection device when the actuator is depressed.

In another aspect of the invention, there is an injection device comprising a needle coupled with a chamber for storing fluid a body portion, an actuator assembly positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing the fluid stored in the chamber from the needle, wherein the actuator assembly is coupled with a rotor, such that movement of the actuator from proximal position to the distal position causes the rotor to rotate, and a damping element coupled, or coupleable, to the rotor in order to damp the rotation of the rotor.

In this way, it is possible for the injection device to damp the progress of the actuator towards the distal position which ensures that the fluid is not dispensed from the needle too quickly.

In another aspect of the invention, there is a method for training a user to use an injection device, the method comprising providing an injection device trainer comprising a body portion, an actuator assembly positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position, wherein the actuator assembly is coupled with a rotor, such that movement of actuator from the proximal position to the distal position causes the rotor to rotate, and a damping element coupled, or coupleable, to the rotor in order to damp the rotation of the rotor. The method further comprises moving the actuator from the proximal position to the distal position during which the damping element damps rotation of the rotor and thus damps movement of the actuator towards the distal position.

In another aspect of the invention, there is a method of administering an injection, the method comprising providing an injection device comprising a needle coupled with a chamber for storing fluid, a body portion, an actuator assembly positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position for dispensing the fluid stored in the chamber from the needle, wherein the actuator assembly is coupled with a rotor, such that movement of the actuator from proximal position to the distal position causes the rotor to rotate, and a damping element coupled, or coupleable, to the rotor in order to damp the rotation of the rotor. The method further comprises moving the actuator from the proximal position to the distal position during which the damping element damps rotation of the rotor and thus damps movement of the actuator towards the distal position.

The locking member may comprise an actuator resistance surface that is arranged to resist movement of the actuator from the proximal position to the distal position, when the locking member is in the first orientation. The actuator resistance surface may comprise a protrusion extending from the locking member. The actuator may comprise an abutment surface that is arranged to abut the actuator resistance surface when the actuator is in the proximal position and the locking member is in the first orientation. The abutment surface may comprise a protrusion extending from the actuator. The locking member may comprise at least two (or a pair of) actuator resistance surfaces. The pair of actuator resistance surfaces may be located on opposite sides of the locking member with respect to one another. The actuator may comprise at least two (or a pair of) abutment surfaces. The pair of abutment surfaces may be located on opposite sides of the actuator with respect to one another. This simple and reliable mechanism enables the force exerted by the actuator on the locking member to be spread across the diameter of the locking member.

The locking member may comprise a cylindrical housing, and the actuator resistance surface may comprise a protrusion that protrudes from the surface of the cylindrical housing. The protrusion may span only partially around the circumference of the cylindrical housing. The locking member may comprise a ramp. The shield may comprise a ramp interface. The ramp interface of the shield may be arranged to interact with the ramp of the locking member when moving from the initial position to the retracted position in order to rotate the locking member from the first orientation to the second orientation. This provides a simple and reliable mechanism for rotating the locking member into the second orientation.

The locking member may comprise a third orientation in which the shield is allowed to move from the initial position to the extended position. The actuator may be configured to move by a first distance in order to move the locking member into the third orientation. In this way, the shield is prevented from moving to the extended position until the actuator has been at least partially depressed. The extended position simulates a locked-out state of an injection device, indicating that injection has been completed. Therefore, the trainer cannot simulate completion of the injection procedure until the actuator has been activated by the user.

The locking member may comprise a stop that is arranged to sit within a recess in the shield, thus holding the shield in the initial position. This provides a simple and reliable mechanism for keeping the shield in the initial position.

The stop may be arranged to move along a slot in the shield in order to allow the shield to move to the extended position. The stop may sit outside of the slot in the recess thus holding the shield in the initial position when the locking member is in the first orientation. In this way, the stop can be used to allow the shield to move from the initial position to the extended position by moving the stop from the recess into the slot.

In an embodiment, movement of the locking member from the second orientation to the third orientation by the actuator pushes the stop into the slot which permits the shield to move from the initial position to the extended position. Therefore, the shield can be allowed to move into the extended position by depressing of the actuator.

The stop may be coupled to a resilient member that is configured to bend in order to move the stop inwards from a resting state towards the longitudinal axis of the trainer into a flexed state. The stop in the resting state holds the shield in the initial position. The stop in the flexed state permits the stop to move into the slot. This provides a reliable mechanism for allowing the shield to move from the initial position to the extended position.

The trainer may comprise a biasing element that biases the shield to move distally. Thus, the shield can move automatically from the retracted position to either the initial position or the extended position, depending on the orientation of the locking member.

The actuator resistance surface of the locking member may comprise a deflector portion. The actuator may be arranged to interface with the deflector portion to move the locking member from the second orientation to the third orientation. Therefore, the actuator pushes down on the deflector portion in order to move the locking member into the orientation that permits the shield to move to the extended position.

The trainer may comprise a biasing element arranged to bias the locking member in a first rotational direction. The biasing element may comprise a torsion spring. The biasing element may bias the locking member to rotate away from the second orientation or the third orientation towards the first orientation. Therefore, it is possible to automatically reset the trainer.

The biasing element may bias the locking member towards a fourth orientation such that once the actuator has moved a distance towards the distal position and the shield is in the extended position the locking member moves into the fourth orientation. The locking member in the fourth orientation may prevent the shield from moving from the extended position to the initial position. Therefore, the shield can automatically be positioned in a locked-out state, once the actuator has been depressed.

The actuator may be configured to interfere with the locking member when moving from the distal position to the proximal position to move the locking member towards the first orientation thus allowing the shield to move from the extended position to the initial position. This allows the user to reset the trainer by moving the actuator back to the proximal position from the distal position.

The locking member may comprise a shield resistance surface that is arranged to resist proximal movement of the shield when the locking member is in the fourth orientation and the shield is in the extended position. The shield may comprise an abutment surface that abuts the shield resistance surface when the locking member is in the fourth orientation and the shield is in the extended position. This assists in maintaining the shield in the locked-out state.

In an embodiment, the proximal position of the actuator simulates an unactivated position of a plunger of an injection device. In an embodiment, the distal position of the actuator simulates an activated position of a plunger of an injection device. In an embodiment, the initial position of the shield simulates covering of a needle of an injection device. In an embodiment, the retracted position of the shield simulates exposing a needle of an injection device. In an embodiment, the extended position of the shield simulates a locked-out state of an injection device in which the shield is prevented from exposing a needle. Therefore, the trainer can accurately simulate the operation of an injection device.

The latch may be configured such that an audible sound is emitted when the latch couples with the body protrusion, thus indicating that the actuator is in the distal position. The audible sound indicates that the actuator has reached the distal position which simulates completion of an injection being administering by an injection device so that the user can more accurately determine that an injection has been administered properly when using the injection device.

The latch is configured to hold the actuator in the distal position when the latch is coupled with the body protrusion. Coupling of the latch to the body protrusion indicates that the actuator has reached the distal position which simulates completion of an injection being administering by an injection device so that the user can more accurately determine that an injection has been administered properly when using the injection device.

The latch comprises a resilient member. The latch is moveable between an uncoupled state in which the latch is not coupled with the body protrusion and a coupled state in which the latch is coupled with the body protrusion. Therefore, the latch simply can be bent into coupling with the body portion.

The resilient member is arranged to move from the coupled state to the uncoupled state when a force above a threshold is applied to the actuator in moving the actuator from the distal position to the proximal position. Therefore, the latch can hold the actuator in the distal position securely, while allowing the trainer to return to its initial configuration when a user purposefully applies a force above the threshold to the actuator.

The latch may comprise a latch deflector portion that is arranged to interface with the body protrusion in order to move the latch from the uncoupled state into the coupled state. The latch may comprise a gripping element that grips the body portion in the coupled state. In this way, the deflector portion assists in moving the latch into coupling with the body, and the gripping element assists in maintain the latch and body in connection with one another.

The resilient member may comprise the deflector portion and/or the gripping element. The deflector portion and the gripping element may be provided on opposite sides of the latch. This provides a reliable construction for the latch.

The connector may resist the shield from moving distally away from the initial position when the actuator is in the proximal position. In this way, the connector assists in maintaining the shield in the initial position.

The connector may allow the shield to move towards the retracted position when the actuator is in the proximal position. In this way, the connector does not impede retraction of the shield to the retracted position.

The connector may allow the shield to move distally towards the extended position when the actuator moves towards the distal position. Thus, the connector can act to release the shield.

The connector may have an actuator interface that abuts a portion of the actuator to resist the shield from moving distally away from the initial position when the actuator is in the proximal position. The abutment of the actuator interface and the actuator provides a mechanism for holding the shield in the initial position.

The actuator interface may abut a surface of the actuator that faces the proximal direction. Thus, the connector can be moved by the actuator when the actuator moves proximally, but the actuator does not move the connector when it moves distally.

The connector may have a shield interface that abuts a portion of the shield to resist the shield from moving distally away from the initial position when the actuator is in the proximal position. This provides a mechanism for holding the shield in the initial position.

The shield interface may abut a surface of the shield that faces the distal direction. Thus, the connector can move the shield when the actuator moves proximally, but the connector does not move the shield when it moves distally.

In another aspect of the invention, there is a kit of parts configured for assembly into an injection device trainer or an injection device as described herein.

Referring to <FIG>, there is an injection device trainer <NUM> for training a user to use an injection device. The trainer <NUM> comprises a body portion <NUM> which has a proximal end <NUM> and a distal end <NUM>.

In use, the distal end <NUM> of the body portion <NUM> is positioned towards a surface of the user's body, which may be a target site into which the user would normally administer an injection. In use, the proximal end <NUM> of the body portion <NUM> is positioned towards the user's hand that is used to activate the trainer <NUM>. The body portion <NUM> also has a window <NUM> in each side of the body portion <NUM> which simulates a window in an injection device that is used to view the medicament contained within the device.

Although the terms "proximal" and "distal" are used herein to describe the device, these terms are used to provide context and do not require the trainer <NUM> to be used in any particular orientation. The terms "first end" and "second end" could be used in place of the terms "distal end" and "proximal end" without changing the intended meaning.

The injection device trainer <NUM> also comprises an actuator <NUM> and a shield <NUM>. The actuator <NUM> simulates the plunger in an injection device that is used to dispense medicament from a needle. The shield <NUM> simulates the needle shield in an injection device that is used to cover and expose the needle.

The trainer <NUM> has a removable cap <NUM> that can be positioned over the shield <NUM> in order to prevent accidental retraction of the shield <NUM>. The cap <NUM> comprises a pair of indents <NUM> on its inner surface. These indents <NUM> are arranged to be positioned over a pair of raised portions <NUM> on an outer surface of the distal end <NUM> of the body portion <NUM>. This holds the cap <NUM> in place. The distal end <NUM> of the body portion <NUM> also comprises a pair of nodes <NUM> on opposite sides of each indent <NUM> that abut with the surface of the shield <NUM>, so that the shield <NUM> is prevented from progressing further towards the proximal end <NUM> once the indents <NUM> have interfaced with the raised portions <NUM>.

The features of the injection device trainer <NUM> described herein may be identical or substantially identical to those of the injection device on which the user is to be trained. However, the injection device trainer <NUM> does not comprise a needle so that a user is not injected during the training procedure. The injection device trainer <NUM> also does not comprise any fluid, such as a medicament, contained within it, although the trainer <NUM> may comprise a container that simulates the vessel for containing the medicament of the injection device.

Referring to <FIG>, there is a sequence for training a user on administering an injection using the injection device trainer <NUM>. As can be seen, <FIG> represents the trainer <NUM> as described with reference to <FIG>. <FIG> illustrates the trainer <NUM> with the cap <NUM> removed which exposes the shield <NUM>. As shown in <FIG>, the shield <NUM> is in an initial position which simulates the position of a needle shield of an injection device in which the needle is covered.

Referring to <FIG>, the user can grip the trainer <NUM> by the actuator <NUM> and position the shield <NUM> over the target site. Then, the user can push the actuator <NUM> towards the distal end <NUM> of the body portion <NUM>. This action causes the shield <NUM> to move in the direction of the proximal end <NUM> to a retracted position of the shield <NUM>. The actuator <NUM> is prevented from moving towards the distal end <NUM> relative to the body portion <NUM>, when the shield <NUM> is in the initial position. Therefore, the actuator <NUM> is held in a proximal position and cannot advance forward. However, once the shield <NUM> is in the retracted the position, the actuator <NUM> is allowed to move in the distal direction along the longitudinal axis of the trainer <NUM>.

<FIG> illustrates the shield <NUM> in the retracted position which is a position more proximal relative to the body portion <NUM> than the initial position. The shield <NUM> is partially retracted inside the body portion <NUM> when in the retracted position. This position simulates the position of a needle shield of an injection device in which the needle is exposed for administering an injection.

Referring to <FIG>, the actuator <NUM> is allowed to move distally once the shield <NUM> is in the retracted position. <FIG> illustrates the actuator <NUM> progressing towards the distal end <NUM>. <FIG> illustrates the actuator <NUM> in a distal position which simulates the position of the plunger in an injection device once the injection has been administered.

Referring to <FIG>, there is a sequence for resetting the injection device trainer <NUM> once simulation of an injection has been completed. Referring to <FIG>, the user can remove the trainer <NUM> from the target site which permits the shield <NUM> to move distally to an extended position that is more distal relative to the body portion <NUM> than the initial position and the retracted position. The extended position of the shield <NUM> simulates a locked-out state of an injection device in which a needle shield of the injection device is prevented from exposing a needle.

Referring to <FIG>, the user can pull the actuator <NUM> towards the proximal end <NUM> in order to reset the trainer <NUM> so that the sequence described with reference to <FIG> can be repeated. <FIG> illustrates the actuator <NUM> progressing towards the proximal position, and <FIG> illustrates the actuator <NUM> once it has reached the proximal position. When the actuator <NUM> is pulled into the proximal position, this causes the shield <NUM> to return to the initial position so that the trainer <NUM> can be used for another instance of training.

<FIG> illustrates an exploded view on the injection device trainer <NUM>. The body portion <NUM> comprises a base portion <NUM> that connects with a main portion <NUM> which is encased by a first outer portion <NUM> and a second outer portion <NUM>. In this example, the component parts of the body portion <NUM> fit together in order to form a body assembly. However, the body portion <NUM> could be formed of a single piece.

The shield <NUM> of the trainer <NUM> comprises an outer shield portion <NUM> and an inner shield portion <NUM>. The outer shield portion <NUM> extends from the base portion <NUM> while the inner shield portion <NUM> sits within the body portion <NUM>. There is also a spring <NUM> which acts as a biasing element for urging the shield <NUM> in the distal direction.

The actuator <NUM> of the trainer <NUM> comprises an actuator body <NUM> and an end cap <NUM>. These components form an external surface with which the user can interact in order to move the actuator <NUM>. There is an inner piece <NUM> of the actuator <NUM> that sits within the actuator body <NUM> and the end cap <NUM>. The inner piece <NUM> connects with a threaded plunger <NUM> at a proximal end of the plunger <NUM>, while a distal end of the plunger <NUM> connects with a tip <NUM> that maintains the plunger <NUM> in alignment with the longitudinal axis of the trainer <NUM>. In this example, the component parts of the actuator <NUM> fit together in order to form an actuator assembly. However, the actuator <NUM> could be formed of a single piece.

The plunger <NUM> is coupled with damping element <NUM> that is used to damp the rotation of the plunger <NUM> which, in turn, damps movement of the actuator <NUM> towards the distal position.

The trainer <NUM> further comprises a locking member <NUM> comprising a first locking portion <NUM> and a second locking portion <NUM>. In this example, the first and second locking portions <NUM>, <NUM> are separate components that connect together to form the locking member <NUM>. However, in another example the locking member <NUM> is formed from a single piece.

The locking member <NUM> is rotatable about the longitudinal axis of the trainer <NUM> such that the locking member <NUM> can be placed in different rotational orientations. The locking member <NUM> can rotate but cannot move proximally or distally with respect to the body portion <NUM>. The locking member <NUM> has a first orientation in which the locking member <NUM> resists movement of the actuator <NUM> from its proximal position (as shown in the <FIG>) to the distal position (as shown in <FIG>). Therefore, the first orientation of the locking member <NUM> is configured to hold the actuator <NUM> in the configuration described with reference to <FIG>. Also, the first orientation of the locking member <NUM> is configured to hold the shield <NUM> in the initial position (as shown in <FIG>) such that the shield <NUM> is prevented from moving from the initial position to the extended position (as shown in <FIG>), and permits movement of the shield <NUM> from the initial position to the retracted position (as shown in <FIG>).

The locking member <NUM> also has a second orientation in which the locking member <NUM> permits the actuator <NUM> to move from the proximal position to the distal position. Therefore, the second orientation of the locking member <NUM> is configured to allow the actuator <NUM> to move into the position illustrated in <FIG>.

The trainer <NUM> also comprises a biasing element <NUM>, which in this example is a torsion spring. The biasing element <NUM> biases the locking member <NUM> in a first rotational direction <NUM>. The first rotation direction <NUM> may be clockwise or anticlockwise depending on the orientation of the trainer <NUM>.

The trainer <NUM> further comprises an inner housing <NUM> that simulates a syringe of an injection device, and a grip <NUM> that holds the inner housing in place.

<FIG> illustrate the trainer <NUM> in the same configuration as described with reference to <FIG> with the actuator <NUM> in the proximal position and the shield <NUM> in the initial position. In this configuration the locking member <NUM> is in the first orientation which prevents the actuator <NUM> moving in the distal direction.

Referring to <FIG> and <FIG>, the locking member <NUM> comprises an actuator resistance surface <NUM> which comprises a protrusion that protrudes from a part of the outside surface of the cylindrical housing of the locking member <NUM>. The actuator resistance surface <NUM> protrudes from the locking member <NUM> in a direction away from the longitudinal axis of the trainer <NUM>. The actuator <NUM> comprises an abutment surface <NUM> which comprises a protrusion that protrudes from a part of the inside surface of the actuator <NUM>. The abutment surface <NUM> protrudes from the actuator <NUM> in a direction towards the longitudinal axis of the trainer <NUM>. The abutment surface <NUM> is arranged to abut against the actuator resistance surface <NUM>. Therefore, the actuator resistance surface <NUM> is arranged to resist movement of the actuator <NUM> from the proximal position to the distal position when the locking member <NUM> is in the first orientation.

In the trainer <NUM> there are two actuator resistance surfaces <NUM>. In this example, the actuator resistance surfaces <NUM> are positioned on opposite sides of the locking member <NUM> to one another. This allows the force of the actuator <NUM> being pressed down to be spread across the locking member <NUM>. There are also two corresponding abutment surfaces <NUM>, which in this example, are positioned on opposite sides of the actuator <NUM> to one another.

The locking member <NUM> comprises a stop <NUM> that is arranged to sit within a recess <NUM> in the inner shield portion <NUM> of the shield <NUM>. The stop <NUM> prevents the shield <NUM> from moving distally from the initial position to the extended position, but permits the shield <NUM> to move proximally towards the retracted position. In this example, the locking member <NUM> comprises a pair of stops <NUM> positioned on opposite sides of the locking member <NUM> to one another. The inner shield portion <NUM> comprises a pair of corresponding recesses <NUM> on opposite sides of the inner shield portion <NUM> to one another. The recesses <NUM> define an aperture with similar, or the same, dimensions as the window <NUM> described with reference to <FIG>.

<FIG> illustrate the trainer <NUM> in the same configuration as described with reference to <FIG> with the actuator <NUM> in the proximal position and the shield <NUM> in the retracted position. In this configuration the locking member <NUM> has been rotated into the second orientation which permits the actuator <NUM> to move in the distal direction, as is described in more detail below.

Referring to <FIG> and <FIG>, the locking member <NUM> comprises a ramp <NUM> which in this example is an angled surface that extends from the outside surface of the second locking portion <NUM>. The inner shield portion <NUM> comprises a ramp interface <NUM> which in this example is an angled surface in a recess in the inner shield portion <NUM>. The ramp <NUM> and the ramp interface <NUM> are shaped and positioned such that when the shield <NUM> is moved from the initial position to the retracted position the ramp interface <NUM> causes the locking member <NUM> to rotate. In this example, the ramp <NUM> and ramp interface <NUM> cause the locking member <NUM> to rotate in a second rotational direction <NUM> which is the opposite rotational direction to the first rotational direction <NUM> towards which the locking member <NUM> is biased.

Preferably, the locking member <NUM> comprises a pair of ramps <NUM> and the shield <NUM> comprises two ramp interfaces <NUM>. Each ramp <NUM> may be on an opposite side of the locking member <NUM> to the other. Each ramp interface <NUM> may be on an opposite side of shield <NUM> to the other. This assists in reducing the frictional forces on the locking member <NUM> and the shield <NUM>.

Movement of the shield <NUM> into the retracted position causes the locking member <NUM> to rotate into the second orientation, which is illustrated in <FIG>. Here it can be seen that the protrusion formed by the ramp <NUM> fits inside the recess formed by the ramp interface <NUM> in order to hold the shield <NUM> in the retracted position. When the locking member <NUM> is in the second orientation, a gap <NUM> formed at an end of the actuator resistance surface <NUM> is at least partially rotationally aligned with the abutment surface <NUM>, such that the abutment surface <NUM> can pass through the gap <NUM>. Therefore, the abutment surface <NUM> can move past the actuator resistance surface <NUM>, and the actuator <NUM> can begin to move from the proximal position towards the distal position. The width of the abutment surface <NUM> is the same as or less than the width of the gap <NUM>. In the example, where there are two abutment surfaces <NUM> and two actuator resistance surfaces <NUM>, the same process as described above occurs on the opposite sides of the trainer <NUM>.

Referring to <FIG>, the actuator resistance surface <NUM> of the locking member <NUM> comprises a deflector portion <NUM> that is configured to interface with the abutment surface <NUM> of the actuator when the actuator moves distally. When the abutment surface <NUM> interfaces with the deflector portion <NUM>, this causes the locking member <NUM> to move further in the second rotational direction <NUM> from the second orientation to a third orientation. As the actuator <NUM> moves a first distance in the distal direction, the abutment surface <NUM> moves to sit inside the gap <NUM> in the locking member <NUM>. Therefore, the force of the actuator <NUM> moves the locking member <NUM> into the third orientation, which moves the stop <NUM> into a slot <NUM> in the inner surface of the inner shield portion <NUM>. When the abutment surface <NUM> sits within the gap <NUM>, this holds the locking member <NUM> in the third orientation. The abutment surface <NUM> does not extend to the top of the actuator <NUM>. Therefore, once the abutment surface <NUM> has moved past the gap <NUM> and the shield <NUM> has moved out of the engagement with locking member <NUM>, it is possible for the locking member <NUM> to rotate back in the first rotational direction due to the force applied by the biasing element <NUM>.

The slot <NUM> in the inner shield portion <NUM> forms a track within which the stop <NUM> can slide. The slot <NUM> has an opening <NUM> at a proximal end of the inner shield portion <NUM>. The slot <NUM> permits the shield <NUM> to move in the distal direction from the retracted position towards the extended position, and once the stop <NUM> reaches the opening <NUM> the inner shield portion <NUM> is released from contact with the locking member <NUM>.

The shield <NUM> is allowed to move into the extended position when the stop <NUM> exits the opening <NUM> of the slot <NUM>. This permits the shield <NUM> to move past the locking member <NUM> to the extended position, which is more distal than the position of the locking member <NUM> and more distal than the initial position. The location of the shield <NUM> relative to the locking member <NUM> when the shield <NUM> is in the extended position is shown in <FIG>, which is the configuration described with reference to <FIG>.

Referring to <FIG>, the stop <NUM> comprises a resilient member <NUM> that is configured to be flexed inwards by the inner shield portion <NUM>. Thus, the resilient member <NUM> and the stop <NUM> can move inwards towards the longitudinal axis of the trainer <NUM>. The stop <NUM> is forced against an edge of the recess <NUM> when the actuator <NUM> forces the locking member <NUM> to rotate from the second orientation to the third orientation. This pushes the stop <NUM> and the resilient member <NUM> inwards, so that the stop <NUM> can enter the slot <NUM> in the inner shield portion <NUM>. As illustrated, the stop <NUM> has an angled surface, which assists in flexing the resilient member <NUM> inwards.

When the trainer <NUM> is in the state illustrated in <FIG> and <FIG>, the actuator <NUM> no longer holds the locking member <NUM> in the third orientation, and the ramp <NUM> can no longer touch the ramp interface <NUM>. Therefore, the locking member <NUM> is free to rotate in the first rotational direction <NUM>, and is urged in this direction by the biasing element <NUM>.

The locking member <NUM> rotates past the first orientation and into a fourth orientation in which a portion of the actuator <NUM> abuts a reset deflector <NUM> on the locking member <NUM>. This holds the locking member <NUM> in the fourth orientation, which prevents the shield <NUM> from moving proximally from the extended position towards the initial position. Therefore, the shield <NUM> simulated a locked-out state of an injection device.

When the locking mechanism <NUM> is in the fourth orientation, a shield resistance surface <NUM> abuts against a surface on the proximal end of the inner shield portion <NUM>. In this example, the shield resistance surface <NUM> is a protrusion extending from the ramp <NUM>. The shield resistance surface <NUM> blocks the path of the shield <NUM>, so that it cannot move proximally from the extended position.

As described above with reference to <FIG>, the user can reset the trainer <NUM> by pulling the actuator <NUM> from the distal position back to the proximal position. When the actuator <NUM> moves in the proximal direction the abutment surface <NUM> interfaces with an angled surface of the reset deflector <NUM> in order to rotate the locking mechanism <NUM> from the fourth orientation into the first orientation.

When the locking member <NUM> has rotated by a first angular distance in the second rotational direction <NUM> towards the first orientation, the shield resistance surface <NUM> is no longer directly above the proximal end of the inner shield portion <NUM> in the direction of the longitudinal axis of the trainer <NUM>. Instead, the shield resistance surface <NUM> is directly above a recess in the inner shield portion <NUM> in the direction of the longitudinal axis of the trainer <NUM>. Therefore, the shield <NUM> is able to move towards the initial position from the extended position.

When the shield <NUM> is moved from the extended position back towards the initial position, the ramp interface <NUM> of the shield <NUM> exerts a force on the ramp <NUM> of the locking member <NUM>. This causes the locking member <NUM> to move in the second rotational direction <NUM> towards the first orientation. As the inner shield portion <NUM> moves proximally, this forces the stop <NUM> and the resilient member <NUM> to flex inwards such that the stop <NUM> passes under the proximal end of the inner shield portion <NUM>. As the inner shield portion <NUM> moves further, the stop <NUM> moves into the recess <NUM>, which holds the shield <NUM> in the initial position as described above. In addition, once the shield <NUM> has reached the initial position, the locking member <NUM> has rotated into the first orientation as described above. Therefore, the trainer <NUM> can be reset back to the configuration described with reference to <FIG>.

It is possible to move the shield <NUM> from the extended position in the direction of the initial position by hand in order to reset the device. However, this requires the user to move the actuator <NUM> into the proximal position at the same time as moving the shield <NUM> to the initial position in order to reset the device, thus requiring the use of two hands which is undesirable. Referring to <FIG>, a reset connector <NUM> is provided that automatically pulls the shield <NUM> from the extended position into the initial position when the actuator <NUM> is pulled from the distal position into the proximal position.

The reset connector <NUM> is a rod of fixed length comprising an actuator interface, such as a first hook <NUM>, at its proximal end. The first hook <NUM> is arranged to interface with a portion of the actuator <NUM>, such as a ledge <NUM> on the inner piece <NUM> of the actuator <NUM>. The ledge <NUM> faces in the proximal direction and therefore movement of the actuator in the proximal direction causes the reset connector <NUM> to move in the proximal direction when the ledge <NUM> contacts the first hook <NUM>. However, movement of the actuator <NUM> in the distal direction does not force the reset connector <NUM> to move in this direction, since no force can be applied by the actuator <NUM> on the first hook <NUM> in this direction.

The rest connector <NUM> also comprises a shield interface, such as a second hook <NUM> at its distal end. The second hook <NUM> is arranged to abut with a portion of the shield <NUM>, for instance by being received by an aperture <NUM> in the shield <NUM>. When the reset connector <NUM> is moved in the proximal direction by the actuator moving towards the proximal position, a proximal end 92a of the aperture <NUM> contacts the second hook <NUM>. This permits the reset connector <NUM> to pull the shield <NUM> toward the initial position in order to reset the trainer <NUM>.

The aperture <NUM> may be configured, as illustrated by <FIG>, as an elongated aperture extending distally along the inner shield portion <NUM>. The second hook <NUM> may be positioned within the aperture at all times during operation of the trainer <NUM>. In these embodiments, the second hook <NUM> tracks along the aperture <NUM> as the actuator <NUM> is moved distally from the proximal position, shown in <FIG>, to the distal position, shown in <FIG>, and moved proximally from the distal position towards the proximal position, until the second hook <NUM> contacts the proximal end 92a of the aperture, as described above, to permit the reset connector <NUM> to pull the shield <NUM> toward the initial position in order to reset the trainer <NUM>.

The aperture <NUM> may be formed in any suitable part of the shield <NUM>. For example, the aperture may be formed in the outer shield portion <NUM>, and function in substantially the same manner as described above. The aperture <NUM> may extend, in a direction perpendicular to the longitudinal axis of the trainer <NUM>, through the portion of the shield in which it is formed. Alternatively, the aperture may be an etched portion, or indent, in the surface of the shield <NUM>.

In some embodiments, including that shown in <FIG>, the aperture <NUM> may have a closed distal end. Alternatively, the aperture may be formed as a slot in the distal end of the inner and/or outer shield portion, having a closed, proximal end 92a against which the second hook <NUM> abuts, and an open distal end.

In some embodiments, the aperture may not extend along the shield <NUM> so distally that the second hook <NUM> is positioned within the aperture at all times during operation of the trainer <NUM>. For example, the aperture <NUM> may be configured as an approximately circular aperture in the shield <NUM>. The reset rod <NUM> may be configured such that the second hook <NUM> is resiliently biased into the aperture as the actuator is moved towards its proximal position, to permit contact between the second hook <NUM> and proximal end 92a of the aperture and, therefore, pulling of the shield <NUM> toward the initial position in order to reset the trainer <NUM>. The second hook <NUM> may be shaped, at its distal end, to cam against a closed distal end of the aperture. When the reset rod <NUM> is moved in the distal direction by the actuator moving towards the distal position, camming between the second hook <NUM> and the distal end of the aperture overcomes the resilient biasing, allowing the second hook <NUM> to disengage the aperture <NUM> as the actuator is moved distally.

Referring to <FIG>, the injection device trainer <NUM> comprises a latch <NUM> that is configured to attach to the inner piece <NUM> of the actuator <NUM>. In this example, the latch <NUM> comprises a piece of resilient wire formed in a loop <NUM> that is arranged to be placed around a circular protrusion <NUM> on the inner piece <NUM>. Since the latch <NUM> is resilient, the diameter of the loop <NUM> can be expanded to place it around the circular protrusion. Then, the loop can be released at which point the diameter of the loop <NUM> contracts so that the latch holds the circular protrusion <NUM>. The latch <NUM> also comprises a first extension <NUM> that is configured to be located between a pair of holders <NUM> that hold the latch <NUM> in place.

The latch <NUM> further comprises a second extension <NUM> that in this example is longer than the first extension <NUM>. The second extension <NUM> comprises a first portion <NUM> that extends in the distal direction and a second portion <NUM> that is angled with respect to the first portion <NUM>. The second portion <NUM> forms a deflection portion on its distal side and gripping element on its proximal side. After the actuator <NUM> has moved a certain distance from the proximal position to the distal position, the second portion <NUM> comes into contact with a body protrusion <NUM> on the main portion <NUM> of the body portion <NUM>.

As the actuator <NUM> moves distally, this causes the resilient latch <NUM> to bend outwardly away from the longitudinal axis of the trainer <NUM> and over the body protrusion <NUM>. Once the actuator <NUM> has moved into the distal position, the latch <NUM> returns to its resting position. In this state, the angled surface of the latch <NUM>, which represents the gripping element, couples the latch <NUM> to the body protrusion <NUM>. This holds the actuator <NUM> in the distal position relative to the body portion <NUM>.

When the actuator <NUM> is moved from the distal position to the proximal position, the body protrusion <NUM> exerts force on the latch <NUM>. When this force exceeds a threshold, the gripping element of the second portion <NUM> bends in a direction that is perpendicular to the direction that extends away from the longitudinal axis of the trainer <NUM>. Thus, the gripping element passes by the body protrusion <NUM>, so that the actuator <NUM> can be released from distal position. The threshold force required to bend the latch ensures that the actuator <NUM> is held securely in the distal position. However, the threshold force also permits the actuator <NUM> to snap back into the proximal position, once the gripping element releases the body protrusion.

Referring to <FIG>, the damping element <NUM> described briefly with reference to <FIG> is described in more detail below.

In the trainer <NUM>, the plunger <NUM> of the actuator <NUM> has a thread which is coupled with a rotor <NUM>. The rotor <NUM> may include an internal thread <NUM>, configured to engage the thread of plunger <NUM> to facilitate coupling of the plunger <NUM> and rotor <NUM>. The plunger <NUM> is fixed to the inner piece <NUM> of the actuator <NUM> such that the plunger does not rotate relative to the actuator <NUM>. The rotor <NUM> interfaces with the thread, and therefore the plunger <NUM> causes the rotor <NUM> to rotate in the second rotational direction <NUM> as the plunger <NUM> moves distally with the actuator <NUM>. The rotor <NUM> is coupled with damping element <NUM>, which in this example is a torsion spring <NUM> that is biased towards a coiled state. As the rotor <NUM> rotates, the rotor <NUM> uncoils the torsion spring <NUM> which damps rotation of the rotor <NUM> and thus damps progression of the actuator <NUM> towards the distal position. The properties of the spring <NUM> may be selected according to the resistance desired. For example, if high resistance is desired, a spring <NUM> having a high spring constant may be selected.

The damping element <NUM> also comprises a ratchet <NUM> that comprises a plurality of angled teeth which interface with angled teeth <NUM> on the rotor <NUM>. Once the actuator <NUM> is moved by a distance towards the distal position, the angled teeth of the rotor <NUM> are moved into engagement with the angled teeth of the ratchet <NUM>. The rotor <NUM> and ratchet <NUM> form an anti-rotation mechanism that permits the rotor <NUM> to rotate in the second rotational direction <NUM>, but resists movement of the rotor in the first rotational direction <NUM>. In this way, the tension in the torsion spring <NUM> is maintained as the rotor <NUM> uncoils the spring <NUM>, since the torsion spring <NUM> is prevented from moving back to its coiled state.

The angled teeth <NUM> of the rotor <NUM> may each include an angled edge <NUM> (e.g. angled with respect to the longitudinal axis of the trainer) and a straight edge <NUM> (e.g. substantially parallel with respect to the longitudinal axis of the trainer). The rotor <NUM> may be configured such that the angled edge of each tooth faces in the second rotational direction <NUM>. In other words, the angled edge of each angled tooth leads when the rotor <NUM> is caused to rotate as the plunger <NUM> moves distally with the actuator <NUM>. The angled teeth of the ratchet <NUM> approximately tessellate with the angled teeth of the rotor <NUM>. In other words, the straight edges of each tooth of the ratchet <NUM> face in the second rotational direction <NUM>, such that the straight edges of the teeth of the rotor <NUM> abut a respective straight edge of the teeth of the ratchet <NUM> to resist movement of the rotor in the first rotational direction <NUM>. The ratchet <NUM> may be rotationally fixed relative to the actuator <NUM>.

The damping element <NUM> and rotor <NUM> may be configured according to the point at which, during depression of the actuator, engagement of the rotor <NUM> and ratchet <NUM>, and therefore formation of the anti-rotation mechanism, is desired. For example, in embodiments in which a spring <NUM> of high spring constant is used, it may be desirable for the anti-rotation mechanism to engage earlier in depression of actuator <NUM>, to assist a user in resisting the biasing of spring <NUM> back to its coiled state. Earlier engagement of the anti-rotation mechanism earlier may be achieved, for example, by providing angled teeth of the ratchet <NUM> having a greater height along the longitudinal axis of the trainer <NUM>.

When the actuator <NUM> is pulled rather than being pushed, or in other words when the actuator <NUM> is moved proximally, the plunger <NUM> moves the angled teeth of the rotor <NUM> out of engagement with the angled teeth of the ratchet <NUM>. This permits the rotor to move in the first rotational direction <NUM> when the plunger <NUM> moves proximally which moves the spring back to the coiled state. The decoupling distance - the distance by which the actuator <NUM>, plunger <NUM>, and rotor <NUM> are moved proximally in order to move the angled teeth of the rotor <NUM> out of engagement with the angled teeth of the ratchet <NUM> - is a distance greater than the height, along the longitudinal axis of the trainer <NUM>, of the angled teeth of the ratchet. In some embodiments, the decoupling distance may be approximately <NUM>.

The damping element may be implemented in the trainer <NUM> in order to simulate a large volume and/or high viscosity dose. The damping element may also be utilised in injection devices, to force a user to depress the actuator <NUM> slowly when delivering a large dose or a substance of low viscosity (which, itself, may offer little resistance to depression) to mitigate harmful side effects of injecting a substance too quickly, such as excessive bruising, pain, pooling of the injected substance within the patient, etc..

In an alternative embodiment of the damping element, the torsion spring may be coupled to the ratchet. As in the previous embodiment, the rotor interfaces with the thread of the plunger, and therefore the plunger causes the rotor to rotate in the second rotational direction as the plunger moves distally with the actuator. In this embodiment, the rotor is configured such that the straight edges of each tooth face in the second rotational direction. In other words, the straight edge of each angled tooth leads when the rotor is caused to rotate as the plunger moves distally with the actuator. The initial rotation of the rotor in this embodiment does not cause uncoiling of the torsion spring. Hence, initial progression of the actuator towards the distal position is met by little, or no, resistance.

The alternative damping element comprises a ratchet coupled with the torsion spring that is biased towards a coiled state. The ratchet comprises a plurality of angled teeth which interface with angled teeth on the rotor. Once the actuator is moved by a distance towards the distal position, the angled teeth of the rotor are moved into engagement with the angled teeth of the ratchet, such that the straight edges of the teeth of the rotor rotate into abutment with a respective straight edge of the teeth of the ratchet. In this embodiment, once the rotor and ratchet have moved into engagement with one another, continued rotation of the rotor causes the ratchet to rotate. Rotation of the ratchet uncoils the torsion spring, which damps rotation of the ratchet and rotor and thus damps further progression of the actuator towards the distal position. Again, the configuration of the damping element and rotor, for example the spring properties and teeth height, may be selected according to the desired resistance profile.

In some embodiments, the rotor <NUM> and/or damping element <NUM> may be replaceable parts of a trainer or injection device. For example, the device may be configured such that torsion spring <NUM> may be replaced with another spring, of higher or lower spring constant. This facilitates, for example, a single trainer device to be used to train a user in delivering substances of various different viscosities.

An injection device in the context of this application may be an automatic injection device (an auto-injector). In such injection devices, the actuator <NUM> is operated by, or replaced by, an automated actuator such as a drive spring, a pneumatic piston operated by a compressed gas canister, or a solenoid, in an electrically powered automatic injection device.

In such auto-injector devices, the damping element <NUM> may be utilised to damp, slow or control the force applied by the actuator to a container which contains the substance to be injected and/or a delivery mechanism, e.g. a plunger on the drug container, such as a syringe. The damping element may be useful in tuning the speed of an injection by an auto-injector, without requiring alteration of the automated actuator.

The damping element may be configured to operate during any portion of the actuation sequence. For example, the damping element may be configured such that progression of an actuator towards the distal position is damped for the entire duration of the progression, or for only a select portion. In some embodiments, the injection device may be configured such that damping of progression of the actuator begins at the point of full extension of a needle on the drug container, for example to ensure full delivery of the injection substance by an auto-injector.

Unless otherwise indicated each embodiment as described herein may be combined with another embodiment as described herein.

Any reference to "an" item refers to one or more of those items.

References herein to "element" can additionally correspond to "means" for the element performing a particular function as stated herein.

Claim 1:
An injection device (<NUM>) trainer for training a user to use an injection device, the injection device trainer comprising:
a body portion (<NUM>); and
an actuator (<NUM>) positioned towards a proximal end of the body portion, the actuator moveable from a proximal position to a distal position;
wherein the body portion comprises a body protrusion (<NUM>) and the actuator comprises a latch (<NUM>) that is arranged to couple with the body protrusion when the actuator is in the distal position, thus holding the actuator in the distal position,
wherein the latch comprises a resilient member,
wherein the latch is moveable between an uncoupled state in which the latch is not coupled with the body protrusion and a coupled state in which the latch is coupled with the body protrusion,
and characterised in that the resilient member is arranged to move from the coupled state to the uncoupled state when a force above a threshold is applied to the actuator in moving the actuator from the distal position to the proximal position to return the trainer to its initial configuration.