Administration assembly for a medicament delivery device and a medicament delivery device comprising the same

Abstract

The present disclosure relates to an administration assembly (10) for a medicament delivery device (1), comprising: a plunger rod (15), a first resilient member (17) configured to bias the plunger rod(15) in the proximal direction, an elongated plunger rod holder (21) configured to receive the plunger rod (15), an activation sleeve (23) configured to receive a portion of the plunger rod holder (21), and configured to move axially from a first position relative to the plunger rod holder (21) to a second position, wherein the activation sleeve (23) is configured to be biased towards the first position, wherein the plunger rod holder (21) has a first hold and release structure (21a) and the plunger rod (15) has a second hold and release structure (15a), wherein in the first position the activation sleeve (23) is configured to maintain the first hold and release structure (21a) in an axially locking contact position with the second hold and release structure (15a) in which the second holdand release structure (15a) is prevented from movement relative to the first hold and release structure (21a), thereby locking the plunger rod (15) axially relative to the plunger rod holder (21), wherein in the second position the activation sleeve (23) is configured to allow the first hold and release structure (21a) to move from the axially locking contact position, whereby biasing of the plunger rod provided by the first resilient member (17) causes the second hold and release structure (15a) to act with a proximally directed force on the first hold and release structure (21a), moving thefirst hold and release structure (21a) tangentially from the axially locking contact position to thereby release the plunger rod (15) from the plunger rod holder (21).

Description

technical field [0001] The present disclosure relates generally to medical devices. In particular, the present disclosure relates to a drug delivery assembly of a drug delivery device, and a drug delivery device comprising the same. Background technique [0002] Drug delivery devices, especially automatic drug delivery devices such as autoinjectors, are usually spring biased. Activation of such a device may eg be achieved by pushing the device towards the injection site, thereby moving the delivery member shield further into the housing in the proximal direction, or by means of an external button or slider. [0003] WO2011043714 discloses a medicament delivery device comprising a housing, a first activation member, a second activation member, a drive mechanism comprising a plunger rod and a first compression spring, and a needle shield cannula. The second activation member includes a proximally extending flexible tongue configured to engage the plunger rod to retain the pl...

AI Technical Summary

Problems solved by technology

[0004] Thus, prior to use, the flexible tongue is subjected to a forward bias provided somehow by the first compression spring, causing the flexible tongue to weaken over time

This mechanical weakening is the result of the cross-sectional dimension of the flexible tongue decreasing over time

Therefore, in the case of storing the medicament delivery device for a long period of time (for example several years), the plastic structure of the flexible tongue may weaken significantly

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