Patent ID: 7704237

Claim:
A medication dispensing apparatus comprising: a housing; a fluid container mounted to said housing, said container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end; a drive screw with external threading, said drive screw axially extending within said housing and movable distally to advance said movable piston toward said outlet; at least one anti-rotation member operably engaging said drive screw to prevent rotation of said drive screw within said housing; a priming driver axially retained relative to said housing and having a first portion and a second portion, said first portion internal to said housing and in threaded engagement with said drive screw, said second portion external to said housing to be manually rotatable, whereby rotation of said second portion rotates said first portion to force said drive screw to translate distally; a follower axially movable relative to said priming driver and rotatably fixed thereto, said follower including a portion internal to said housing and in threaded engagement with said drive screw; a plunger axially movable relative to said housing between a distal position and a proximal position, said plunger including a manually graspable grip portion which is pullable proximally to move said plunger from said distal position to said proximal position, said plunger connected to said follower to allow relative rotation therebetween and to shift said follower axially when said plunger moves back and forth between said distal and proximal positions; and wherein each of said follower portion and said priming driver first portion comprises a resilient construction, whereby when said plunger is pulled from said distal position to said proximal position to shift said follower proximally, said follower portion slides over said threading of said drive screw that is being axially retained by engagement with said priming driver first portion, and whereby when said plunger is pushed from said proximal position to said distal position to shift said follower distally, said priming driver first portion slides over said threading of said drive screw that is being axially advanced by engagement with said follower portion; and wherein said priming driver first portion comprises a plurality of axially extending fingers angularly spaced around a circumference of said drive screw.