SELECTED DOSE PHARMACEUTICAL DISPENSER

摘要

A dispenser (2) includes a body (4), a needle (110) and one or more hollow cylinders (28) and pistons (144). The needle is movable between a predelivery position and a delivery position, at which the inner needle end (112) opens a ball check valve (142) to permit free fluid flow from the cylinder, along a flow path (46) and through the needle. A threaded dose adjuster (164, 166) is mounted within the body and engages a threaded stem (150). The stem is prevented from rotating so that a rotation of the dose adjuster in one direction causes the dose adjuster to move axially away from the piston to compress a drive spring (176) and preload the stem. Moving the needle assembly to the delivery position causes the dose of pressurized pharmaceutical to be automatically driven from the cylinder and through the needle. The cylinder can be refilled by the user through the needle by opening (88, 92, 94) a supplemental pathway (54, 52) and rotating the dose adjuster in the opposite direction.