ABSTRACT:
Osmotically controlled drug delivery systems (OCDDS) are most promising systems for controlled drug delivery. Osmotically controlled drug delivery systems utilize osmotic pressure for controlled delivery of active agents. Various patents are available for osmotic drug delivery system like Rose and Nelson pump, Higuchi Leeper pump, Higuchi Theeuwes pump, Elementary osmotic pump etc. Various techniques available for preparation of OCDDS include push pull osmotic pump, Osmotic bursting osmotic pump, Liquid OROS, Telescopic capsule for delayed release, OROS-CT (colon targeting), and Sandwiched osmotic tablet system. These systems can be used for systemic as well as targeted delivery of drugs. Drug delivery from these systems, to a large extent, is independent of physiological factors of GI tract. Release of drug from formulation is depends on various formulation factors such as solubility of drug, osmotic pressure generated in the system, size of the drug delivery orifice, nature and thickness of rate controlling membrane. The present review article mainly focus on the basic components of osmotically controlled drug delivery system, various factors governing drug release from these systems and types of osmotically controlled drug delivery systems. Osmotic drug delivery systems differ from diffusion based systems in that the delivery of the active agents is driven by an osmotic gradient rather than the concentration of drug in the device.