Osmotic drug delivery systems: basics and design approaches

Osmotic drug delivery system utilizes the principles of osmotic pressure for the controlled delivery of active pharmaceutical ingredient at a predetermined zero order rate. An appropriately designed osmotic drug delivery is not influenced by different physiologic factors but affected by pharmaceutical factors, which play a pivotal role in modulating the release of drug. The present review critically discussed about the factors affecting drug release from the delivery system such as solubility, osmotic pressure, size of delivery orifice and membrane characteristics. The major arena of this review is to highlight about the different types of osmotic drug delivery systems such as implantable, single chamber, multi chamber osmotic pumps and several specialized type of osmotic pumps. Apart from that this system is a versatile technology useful for delivery of drugs with varying solubility. The additional properties of this delivery system can also exhibit pulsatile release, burst release and colon targeting of drug. Because of its versatility, this above system seems to have promising approach which can result in improved safety profile, stable drug concentrations, uniform drug effects and dosing frequency. Current review also briefly discussed about the patents related to delivery of drugs by the principle osmotic pressure.