CLINICAL AND EXPERIMENTAL STUDIES WITH 8-METHOXYPSORALEN IN VITILIGO

[摘要] Oral admn. of 8-methoxypsoralen (xanthotoxin, ammoidin), together with exposure of areas of vitiligo to u.-v. light, is effective treatment for some cases of vitiligo. Oral use of this drug decreases the erythema response of patients to u.-v. light, whereas local appln. increases this response. In appropriate doses 8-methoxypsoralen is well tolerated by patients. Complete blood studies, urinalyses, examinations for urinary porphyrins, prothrombin times, and liver function tests, except the cephalin cholesterol flocculation test, were within normal limits. Some patients had weakly positive cephalin cholesterol flocculation tests after 2 mos. therapy. It is suggested that this test be done monthly for 3 mos., and then at less frequent intervals, on patients receiving the drug. The LD50 for adult mice and rats is approx, 400-600 mg./kg. The molecular extinction coefficient for 8-methoxypsoralen and 8-isoamylenepsoralen is given. Solns. of 8-methoxypsoralen before and after exposure to u.-v. light have no effect on the tyrosine, dopa-, or glutathione inhibited-tyrosinase systems, or on the histochemical skin tests for tyrosinase activity. The solns. also did not affect the melanocytes of isolated frog skin. The effect of u.-v. light on the optical density of solns. of 8-methoxypsoralen is shown.