Topical delivery of liposomally encapsulated interferon evaluated by in vitro diffusion studies.

The topical delivery of several liposomal interferon formulations was evaluated by in vitro diffusion experiments in an effort to understand the effects of liposomal composition and method of preparation on the deposition of interferon into the stratum corneum and deeper strata of the skin. Application of liposomes prepared from lipids with a composition similar to that of the stratum corneum resulted in almost twice the amount of interferon being deposited in the deeper skin layers than did application of liposomes prepared from phospholipids. Topical application of "skin lipid" liposomes prepared by the dehydration-rehydration method was twice as effective as was topical application of liposomes prepared by the reverse-phase evaporation method with respect to their ability to deposit interferon into the skin strata where the basal cell layers reside. These results are consistent with the effects of liposomal composition and method of preparation on the ability of the formulation to reduce lesion scores in the cutaneous herpes simplex virus type 1 guinea pig model.