HPLC determination of the stability of tretinoin in tretinoin–minoxidil solution

Abstract

A new formulation of topical tretinoin–minoxidil solution was prepared and the chemical stability of tretinoin was studied for 6 months at 4°C. A reversed phase high performance liquid chromatography (HPLC) method was developed for determination of tretinoin using cyanocobalamine as an internal standard. Tretinoin was shown that to be stable for at least 6 months used refrigerated storage conditions.