Cyclosporin A in skin samples from in vitro penetration studies may be assayed by a simple HPLC method

Abstract

A simple High Performance Liquid Chromatographic method with UV detection was developed for quantification of Cyclosporin A (CysA) in skin samples after in vitro penetration studies. The peptide was recovered from two different layers of skin, the stratum corneum and the epidermis plus dermis ([E+D]), by vortex homogenization and bath sonication in an organic solvent (methanol). Recovery of CysA from skin was about 85%, and CysA was estimated by HPLC using a RP-18 column, UV detection at 210 nm and acetonitrile:water (67:33 v/v) as the mobile phase. The quantification limit was 150ng/mL. The assay was linear from 0.15-500 mg/muL. The within-day and between-day assay precision and accuracy were studied at three concentration levels (1, 10 and 20 mug/mL). The coefficients of variation and deviation from the theoretical values were lower than 5%. The method described has a potential application to in vitro penetration studies of CysA using porcine skin as a biological membrane model.