Evaluation of Chemical Stability and Skin Irritation of Lawsone Methyl Ether in Oral Base

An antifungal naphthoquinone, lawsone methyl ether, was semisynthesized by methylation of lawsone. It exhibited low acute toxicity with a LD 50 of 70.7 mg/kg upon intraperitoneal administration in mice. An oral preparation of 0.5 % lawsone methyl ether in sodium carboxymethyl cellulose oral base appeared to be stable under a heating-cooling cycle test. Lawsone methyl ether in oral base did not cause any skin irritation under a primary skin irritation test and a cumulative skin irritation test. In contrast, the solution of lawsone methyl ether, potassium salt, produced erythema with some papulosquamous in the cumulative skin irritation test.