FORMULATION OF PROLONGED RELEASE LIPID MICROPELLETS BY EMULSION CONGEALING - OPTIMIZATION OF KETOPROFEN ENTRAPMENT AND RELEASE

An emulsion-congealing technique was used to prepare prolonged release lipid micropellets containing ketoprofen. The lipid matrix consisted of cottonseed oil/beeswax mixture and was emulsified at 70 degrees C i nto 0.1 N HC1 containing Tween 60 and gelatin. The studied formulation factors were the amounts of drug, Tween 60 and gelatin, in addition t o the matrix composition and rate of cooling. The optimization protoco l required preliminary formulation studies (11 batches) to help choose suitable levels for formulation factors, and a central composite desi gn (17 batches) to correlate simultaneously some of these factors to m easured variables, e.g., drug entrapment, particle size and dissolutio n parameters. The adopted optimization strategy led to formulation of micropellets of about 1.5 mm in diameter and 25% w/w drug loading with prolonged release characteristics. The study design offers adequate p rediction of micropellet characteristics and provides a basis for deve lopment of other micropellet systems.