US Patent 6997922 Osmotic delivery system having space efficient piston

An osmotic delivery system having a space-efficient piston is provided. The enclosure has an interior holding the piston, a beneficial agent, and an osmopolymer including a tablet. The piston is movable with respect to an interior surface of the capsule, and defines a movable seal with the interior surface of the capsule. The movable seal separates the osmopolymer from the beneficial agent. The piston has a recess that receives at least a portion of the osmopolymer. The osmopolymer imbibes liquid from a surrounding environment through a semipermeable body to cause the piston to move and, in turn, cause delivery of the beneficial agent from the capsule.