Auto-injector

Abstract

The invention refers to an auto-injector (1) for administering a dose of a liquid medicament (M), comprising: - a tubular chassis (2) telescopable in a tubular case (12), - a carrier subassembly comprising a tubular carrier (7) slidably arranged relative to the chassis (2) inside the case (12), the carrier (7) adapted to contain a syringe (3) with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3), wherein the syringe (3) is lockable for joint axial translation with the carrier (7), - a trigger button (13) arranged distally or laterally in or on the case (12), - a control spring (19) arranged around the carrier (7), - a needle extension control mechanism (24) for coupling a proximal end of the control spring (19) to either the carrier (7); for advancing it for needle extension or to the chassis (2) for needle retraction depending on the relative axial position of the carrier (7) and the chassis (2), - a plunger release mechanism (27) arranged for releasing the plunger (9) for injection when the carrier (7) has at least almost reached an extended proximal position, - a detent mechanism (18) arranged for coupling the chassis (2) to the carrier (7) for joint axial translation relative to the case (12), wherein the detent mechanism (18) is arranged to decouple the chassis (2) from the carrier (7) upon actuation of the trigger button (13), thus allowing the carrier (7) to move relative to the chassis (2) so as to cause the needle extension control mechanism (24) to switch the proximal end of the control spring (19) to the carrier (7) for needle extension, and a syringe retraction control mechanism (25) arranged for coupling a distal end of the control spring (19) to either the carrier (7) for needle retraction or to the case (12) otherwise.

Description

technical field [0001] The invention relates to an automatic injection device for administering doses of liquid medicaments according to the preamble of claim 1 . Background technique [0002] Administering injectables presents many risks and challenges, both psychologically and physically, for users and healthcare professionals. [0003] Injection devices (ie devices capable of delivering medicament from a medicament container) typically fall into two types - manual devices and automatic injection devices. [0004] In manual devices, the user must provide mechanical energy to drive fluid through the needle. This is typically done with some form of button / plunger which the user must continuously depress during an injection. This solution has a number of drawbacks for the user. If the user stops pressing the button / plunger, the injection will also stop. This means that if the device is not used properly (ie the plunger is not fully depressed to its end position), the user...

AI Technical Summary

Problems solved by technology

This can cause the user to feel a strong impact when the needle is inserted into the skin, and a strong force when the injection is triggered

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