Microencapsulation of drugs by pan and air suspension techniques

This review examines recent advances in the commercial production of microencapsulated drug products. Factors influencing drug selection are considered with particular reference to the design of controlled drug delivery systems. The formulation of both aqueous and nonaqueous coating materials is discussed with examples of common problems encountered in applied coatings and ways to overcome same. Methods of core production are considered with emphasis on spheronization procedures. Pan and air suspension techniques, together with modification thereof, are discussed. Certain newer in vitro procedures such as scanning electron microscopy with energy dispersive analysis or topographical plots of dissolution data for complex microencapsulated systems are presented. Finally aspects of the stability and in vivo testing of microencapsulated products are considered in the context of requirements for regulatory approval.