CA2557897C — Medication dispensing apparatus with spring-driven locking feature enabled by administration of final dose

USPTO Abstract

A medication dispensing apparatus with a spring-driven locking feature includes a drive member movable in a distal direction within a housing, and a fluid container with a piston that is advanceable by the drive member (60) when such drive member is moved distally by a driving means. The apparatus includes a latching element (180) having a skid (190) that is slidable along a surface of the drive member as the drive member passes distally during advancement. The drive member is arranged with the skid so as to maintain a latching lip of the latching element against a spring force in a first position free of the driving means during dose preparing and injecting prior to a final dose administration. The skid-engaging surface shifts distally of the skid such that the skid passes beyond a proximal end of that surface upon administration of a final dose, whereby the latching lip is urged by the spring force from the first position to a second position to physically lock the driving means to prevent further dose preparing and injecting.