DETERMINATION OF ADAPALENE (CD271 DIFFERIN(R)) AND RETINOL IN PLASMA AND TISSUE BY ONLINE SOLID-PHASE EXTRACTION AND HPLC ANALYSIS/

Adapalene, the active constituent of Differin(R), is a novel potent re tinoid (vitamin A analogue) for the topical treatment of acne vulgaris . The clinical usefulness of retinoids is limited by a number of side effects, such as teratogenicity and skin irritation. A method has been developed for simultaneous determination of adapalene and retinol in plasma and tissue in in vivo and in vitro studies for the determinatio n of the pharmacokinetic profile and the influence of adapalene on the endogenous retinol level. The new method was developed by coupling an autosampler to an automated solid-phase extraction unit on-line with a gradient HPLC system using UV and fluorescence detection. The low de tection limit (0.25 ng mL(-1) for adapalene), the small sample weight (50 mg) and the high degree of automation make this method convenient for analysis of biological samples in animal and human studies.