Optimizing Dermatological Formulations of Retinoic Acid

Formulations of retinoic acid for the topical treatment of ichthyosiform and seborrheic dermatoses were developed. They were evaluated for their skin irritation potential on rabbits, as a measure of pharmacological „activity,” by studying erythema and scab-formation times. Different types of vehicles and varying concentrations of retinoic acid were studied. It was found that relatively high concentrations of retinoic acid (0.1-0.2%) were necessary in lipophilic vehicles (in which retinoic acid is relatively insoluble) to achieve a desirable irritation level. Such formulations should be useful for treating ichthyosiform dermatoses. Conversely, it was found that relatively low concentrations of retinoic acid (0.001-0.050%) were preferable in hydrophilic vehicles (in which retinoic acid is relatively soluble) to achieve a desirable irritation level. Such formulations should be useful for treating seborrheic dermatoses.