Patent ID: 7517334
Filing Date: 2009-04-14
Classification: A61M

Abstract:
1. A medication dispensing apparatus comprising: a housing; a drive member within said housing and movable in a distal direction; a fluid container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end, said piston engageable by said drive member to be advanced toward said outlet a distance equal to a distal movement of said drive member when said drive member is moved distally; a plunger element; a gear set including first and second pinions, said gear set pivotal on said plunger element and shiftable proximally and distally with the plunger element; a first rack engaged with said first pinion and axially stationary within said housing; a second rack engaged with said second pinion and movable within said housing on a piece clutchably connected to said drive member; a latching element including a latching lip and a skid; said drive member including an axially extending, skid-engaging surface along which said skid is slidable as said drive member passes distally during advancement during plunger element shifting in the distal direction, said skid-engaging surface having an axial length and a proximal end, said drive member along said axial length structured and arranged with said skid so as to maintain said latching lip against a spring force in a first position free of a latchable element disposed on said plunger element during dose preparing and injecting prior to a final dose administration; and wherein said skid-engaging surface shifts distally of said skid such that said skid passes beyond the proximal end upon administration of a final dose allowing said latching lip to be urged by said spring force from said first position to a second position for engagement with said latchable element to physically lock said plunger element to prevent further dose preparing and injecting.