Résumé
Multiple emulsions have been proposed to have numerous uses including their use for enhancement of bioavailability or as a prolonged drug delivery system. But the inherent instability of this system needs to be overcome before they find potential application in pharmaceuticals. Multiple emulsions are often stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of these surfactants is important in achieving stable multiple emulsions. Atorvastatin was selected as a model drug to study the potential of multiple emulsion to improve bioavailability with the hypothesis that improvement of drug release profile will reflect the enhancement of bioavailability of the drug. The objective of this study was to prepare multiple emulsion of Atorvastatin by two step emulsification using nonionic surfactants, and evaluate for stability, percentage drug entrapment, in-vitro & ex-vivo drug release. Different formulation variables like type & proportion of primary & secondary emulsifier and phase volume ration of internal phase:external phase; and process variables like speed & time of stirring during primary & secondary emulsification were optimized to get stable multiple emulsion with high entrapment efficiency. The study concluded that stable multiple emulsion with high entrapment efficiency can be prepared by two step emulsification method using Span60 as primary and Tween80 as secondary emulsifier at 30:70 phase volume ratio of internal phase:external phase with optimized speed of stirring at 5000 r/min for 10 mins for primary emulsification and 1500 r/min for 7 mins for secondary emulsification.