Effect of vehicle on topical liposomal drug delivery: Petrolatum bases

Liposomes used for topical applications are often incorporated into a vehicle to achieve suitable viscosity and application properties. The effect of incorporation of liposomes into white petrolatum as a possible dermatological base was investigated. A number of formulae mere developed to determine the type of petrolatum base that would be compatible with the liposomes. The physical appearance and stability of the vaseline-liposome (VL) preparations were determined by organoleptic analysis and microscopy. The effect of petrolatum base on the drug release from the liposomes was determined in a flow-through diffusion cell system using a model silastic polymer membrane as barrier. A base containing white petrolatum 46.7% (w/w), stearyl alcohol 6.7% (w/w), cholesterol 13.3 (w/w), Tween 80 16.7% (w/w) and Span 16.7% (w/w) was selected for diffusion studies, since the mixture of this base and liposome preparation, at 1:1.9(w/w) ratios, provided a stable, dermatologically acceptable dosage form, in which the liposomes were uniformly distributed and their structures were preserved. Diffusion studies showed that the drug release rate decreases 2.5 x when the liposomes are incorporated into the vaseline base; however, after a temporary decrease they seem to extend the duration of release beyond that of the original liposomal formula. These studies revealed a possibility of using white petrolatum in the topical application of liposomes.