A new type of therapeutic system, the precision release osmotic form, has recently been developed. This new dosage form has been referred to in other publications as the gastro-intestinal therapeutic system (GITS). Its action is based on the principles of osmosis as a means of delivering precise amounts of drug over prolonged periods of time. The precision release form has evolved from a prototype design through a simplification and miniaturization process into the elementary osmotic pump, a simple, elegant delivery form that permits controlled drug release by osmosis. Sodium indomethacin trihydrate is the first drug to be incorporated into this precision release form ('Osmosin'). Comparisons with conventional drug forms have shown 'Osmosin' to produce more sustained and constant drug release profiles, thus aiming to improve the therapeutic applicability of a drug through a reduction in dose-related side-effects and allowing once-daily dosing.