Patent ID: 8376993

Claim:
A medicament dispensing mechanism configured to eject successive doses of the medicament from a medicament chamber, comprising: a housing; a plunger rod configured for ejecting the doses of medicament from the chamber; and an actuation mechanism that comprises a trigger associated with the housing and having a ready position and a fired position with respect thereto, the trigger being configured for manipulation by a user for successive movement in: a dosing motion from the ready position to the fired position generally in axial translation in which the trigger is associated with the plunger rod to cause the plunger rod to eject one of the doses of a predetermined volume, and a resetting motion from the fired position to the ready position that comprises axial rotation, wherein the trigger is uncoupled from the plunger rod during the resetting motion; and an anti-retrograde mechanism associated with the actuation mechanism and configured to prevent movement of the actuation member in a direction opposite to an operational direction associated with each of the dosing motion and the resetting motion; wherein the anti-retrograde mechanism prevents the actuation mechanism from returning to the ready position associated with the dosing motion from the fired position associated with the dosing motion.