Osmotically controlled oral drug delivery

It is advantageous to deliver some drugs with short half-life, and which ar e to be given frequently for chronic ailments, in the form of controled-rel ease (CR) formulations. The orally administered drugs, in the form of conve ntional matrix or reservoir type formulations, pose problems of bioavailabi lity fluctuations due to gastric pH variations. Moreover, the release of dr ug(s) from these systems is affected by the hydrodynamic conditions of the body. Osmotically controlled drug delivery systems utilize the principles o f osmotic pressure for the controlled delivery of active agent(s). The rele ase rate of drug(s) from these systems is independent of the physiological factors of the gastrointestinal (GI) tract to a large extent. In the presen t review, theory underlying the delivery of drugs from osmotic systems is p resented. Different types of oral osmotic systems, their advantages over co nventional matrix and reservoir types of systems, and their applications ar e also discussed. Finally, some of the limitations, adverse effects, and pa tent and market status of these systems are reviewed. These systems form a major segment of drug delivery products. Because of their advantages and st rong market potential, it appears that the future of osmotic systems in rat e-controlled oral drug deliver is promising.