Bioavailability of clobetasol propionate - Quantification of drug concentrations in the stratum corneum by dermatopharmacokinetics using tape stripping

The concentration of clobetasol propionate in the stratum corneum after app lication of three different formulations was determined, quantifying the in fluence of the formulations on the bioavailability of the drug. The stratum corneum was sampled by tape stripping. The concentrations of clobetasol pr opionate were determined quantitatively by HPLC. After application of Clobe tasol Propionate Cream USP, 0.05%, and Temovate Cream, 0.05%, identical amo unts of the drug were found in the stratum corneum, whereas after applicati on of Temovate epsilon Emollient 0.05%, the quantity was clearly decreased. From results obtained measuring the drug concentration in the adjacent sit es of the skin where the creams had not been applied, it became clear that clobetasol propionate in Temovate epsilon Emollient, migrated to a large ex tent in the lateral direction. This explains the lower concentration measur ed for this formulation in the skin areas where the cream had been applied. In general, a lateral distribution of the applied drug must be taken into account when positioning the application areas on the forearm.