Topical delivery of ciclosporin: evaluation of various formulations using in vitro diffusion studies in hairless mouse skin.

The kinetics and extent of uptake of ciclosporin in various strata of hairless mouse skin upon topical application of several ciclosporin formulations were determined by in vitro diffusion cell experiments. The ciclosporin formulations tested included a hydroalcoholic solution, an oil-in-water emulsion and two liposomal systems. The accumulation of drug in stratum corneum is in the order: 'skin lipid' liposomes greater than 'phospholipid' liposomes greater than emulsion greater than hydroalcoholic solution. The total combined amount of drug in the deeper skin strata and the receiver compartment followed the order: hydroalcoholic solution much greater than 'phospholipid' liposomes greater than 'skin lipid' liposomes greater than emulsion. The results suggest that topically applied liposomes, particularly those prepared from lipid mixtures having compositions similar to the stratum corneum, may provide sustained, enhanced levels of ciclosporin in the stratum corneum (the reservoir) while minimizing high levels in strata associated with blood and lymph supplies.