Photochemotherapy: identification of a metabolite of 4, 5', 8-trimethylpsoralen

A compound, 4, 8-dimethyl, 5'-carboxypsoralen (DMeCP), has been identified in mouse urine as a major metabolite of the photoactive drug, 4, 5', 8-trimethylpsoralen (TMeP). This drug is widely used in the treatment of vitiligo and psoriasis. DMeCP is fluorescent, and nonphotosensitizing when tested on guinea pig skin. DMeCP also occurs in the urine of human patients receiving TMeP orally.