Minimally compliant, volume-efficient piston for osmotic drug delivery systems

An osmotic delivery system comprising:

• a piston having a length to overall diameter ratio not greater than about 1.1:1 and a core diameter to overall diameter ratio not greater than about 0.9:1;
• an osmotic agent;
• and
• an enclosure having an interior holding the piston and the osmotic agent, the piston being movable with respect to the enclosure.

An osmotic delivery system comprising:

• a capsule having a tubular interior, the tubular interior having an interior surface;
• a semipermeable body located at least partially within the tubular interior;
• an osmotic agent located between the semipermeable body and a piston;
• a beneficial agent located within the tubular interior;
• and
• a piston located within the tubular interior, the piston having a length to overall diameter ratio less than about 1.1:1 and a core diameter to overall diameter ratio less than about 0.9:1, the piston separating the beneficial agent from the osmotic agent, and being movable with respect to the interior surface of the tubular interior and with respect to the semipermeable body.