An article in the July issue of the Archives of Dermatology reports that Melanotan-1, a synthetic agent similar to the body's hormone that regulates skin pigmentation, can be combined with UV-B light or sunlight, and appears to act synergistically in the tanning response to light.
Melanotan-1 (MT-1) is a synthetic super-potent derivative of its natural counterpart, alpha-melanocyte-stimulating hormone, one of a family of hormones that induce pigmentation in the body. According to information in the article, the authors previously demonstrated that MT-1 can induce tanning in human volunteers who are known to tan easily in response to sunlight. All previously reported clinical trials with MT-1 were performed with volunteers who were instructed to avoid sunlight and use sunscreens with a sun-protective factor rating of 30 on all skin sites exposed to the sun. The effect of MT-1 when combined with either sunlight or simulated UV-B radiation had not been tested.
Robert T. Dorr, Ph.D., of the University of Arizona, Tucson, and colleagues performed three phase one clinical trials to demonstrate safety for MT-1 therapy combined with UV-B light or sunlight. In the first study, four subjects were randomized to 0.08 milligrams per kilogram of MT-1 per day administered by injection, and four others received injections of isotonic sodium chloride solution (solution containing the same concentration of salt as normal body fluids) for ten days. It was followed by neck irradiation with UV-B light.
In the second study, 12 subjects received MT-1. The dosage was increased to 0.16 milligrams per kilogram per day for ten days, with UV-B radiation given to a buttock site for five days during or after MT-1 administration. The final study randomized eight subjects to three to five days of sunlight to half of the back, or to sunlight plus 0.16 milligrams per kilogram of MT-1, for five days per week for four weeks.