Studies on Skin Irritancy of Topical Agents “Second Report

Skin irritancy of topical agents was studied by 48 hours closed patch test. First of all, 69 topical agents were patch tested to 241 patients with dermatoses and evaluated according to the Japanese standards. From the results, the reaction patterns of the irritancy of topical agents were divided into 6 classes according to the degrees of the strongest reactions and time course changes of the reactions. The characteristics of the irritancy of topical agents seem to be clarified to some extent by our classification of reaction patterns. Secondly, 25 topical agents and their vehicles offered by some pharmaceutical companies were patch tested to 33 patients with dermatoses to study skin irritancy and interactions between active ingredients and their vehicles. The results showed that the topical agents including high concentrations of propylene glycol reacted stronger at 72 reading than 48 reading. The cause was assumed that irritant reactions of the vehicles became stronger at 72 reading, while the active ingredients or corticosteroids were rapidly absorbed percutaneously.