TECHNICAL FIELD

This disclosure relates to an autoinjector.

BACKGROUND

Administering an injection is a process which presents a number of risks and challenges for users and healthcare professionals, both mental and physical. Injection devices typically fall into two categories—manual devices and autoinjectors. In a conventional manual device, manual force is required to drive a medicament through a needle. This is typically done by some form of button/plunger that has to be continuously pressed during the injection. There are numerous disadvantages associated with this approach. For example, if the button/plunger is released prematurely, the injection will stop and may not deliver an intended dose. Further, the force required to push the button/plunger may be too high (e.g., if the user is elderly or a child). And, aligning the injection device, administering the injection and keeping the injection device still during the injection may require dexterity which some patients (e.g., elderly patients, children, arthritic patients, etc.) may not have.

Autoinjector devices aim to make self-injection easier for patients. A conventional autoinjector may provide the force for administering the injection by a spring, and trigger button or other mechanism may be used to activate the injection. Autoinjectors may be single-use or reusable devices.

There remains a need for an improved autoinjector.

SUMMARY

It is an object of the present invention to provide an improved autoinjector.

In an exemplary embodiment, an autoinjector according to some aspects of the present invention comprises a case adapted to hold a medicament container having a needle and the case including a rib, a needle shroud slidably disposed in the case and translatable between an extended position relative to the case in which the needle is covered and a retracted position relative to the case in which the needle (4) is exposed, and a plunger slidably disposed in the case. The plunger including a plunger boss adapted to abut the rib and the needle shroud when the needle shroud is in the extended position and disengage the rib when the needle shroud is in the retracted position to allow the plunger to translate axially relative to the case.

In an exemplary embodiment, a first shroud boss on the needle shroud abuts the plunger boss when the needle shroud is in the extended position. A second shroud boss on the needle shroud proximal of the first shroud boss abuts the plunger boss when the needle shroud is in the extended position. A resistance element is formed on the first shroud boss. The resistance element is adapted to engage the plunger boss as the needle shroud translates from the extended position to the retracted position. The resistance element includes at least one of a bump, a ramp, an abutment, a recess, a spring detent and a preloaded beam.

In an exemplary embodiment, a resilient shroud beam on the needle shroud is deflected by a resilient case backstop beam when the needle shroud translates from the retracted position to a second extended position distal relative to the case of the extended position. The resilient shroud beam abuts the resilient case backstop beam when the needle shroud is in the second extended position to prevent proximal movement of the needle shroud relative to the case. The resilient case backstop beam abuts the medicament container when the needle shroud is in the second extended position.

In an exemplary embodiment, the autoinjector further comprises a shroud spring biasing the needle shroud toward the extended position.

In an exemplary embodiment, the autoinjector further comprises a drive spring biasing the plunger relative to the case.

In an exemplary embodiment, the case includes a bayonet slot adapted to engage the plunger boss. The plunger boss partially disengages the bayonet slot when the plunger boss abuts the rib.

In an exemplary embodiment, the rib is angled with respect to a longitudinal axis of the case and imparts a rotational and an axial force on the plunger boss.

In an exemplary embodiment, the case includes a viewing window.

In an exemplary embodiment, the autoinjector further comprises a cap coupled to a protective needle sheath covering the needle.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

