Melanizing Agents

MELANIZING AGENTS          

Melanizing agents are drugs that increase sensitivity to solar radiation and promote re-pigmentation of vitiliginous areas of skin. Psoralens are furocoumarins which on photoactivation stimulate melanocytes and induce their proliferation.

Psoralen It is  obtained from fruit of Ammi majus.

MANADERM 10 mg tablet, 1% ointment, PSORLINE 5 mg tablet, 0.25% solution and ointment.

Methoxsalen (MACSORALEN 10 mg tab, 1% solution, MALANOCYL 10 mg tab, 0.75% soln.) and

Trioxsalen   (0.2% lotion) are synthetic psoralens.

They sensitize the skin to sunlight which then induces erythema, inflammation and pigmentation. They are applied topically as well as given orally. Methoxsalen is absorbed better, undergoes less first pass metabolism and is more effective than trioxsalen. Their plasma t½ is short (~ 1 hr); sensitization of skin is maximal at 1–2 hours, but lasts for 8 hours or more.

Topical Therapy

The solution/ointment is carefully painted on the small well defined vitiliginous lesion—which is then exposed to sunlight for 1 minute and then occluded by bandage or sun screen ointment. Weekly treatment with longer exposures is given. Pigmentation usually begins to appear after a few weeks; months are needed for satisfactory results. Then periodic maintenance treatment may be needed. This therapy should be undertaken only under direct supervision of physician because longer exposure causes burning and blistering.

Oral Therapy

On alternate days after 2 hours of a 0.3–0.6 mg/kg (usually 20 mg) oral dose of a psoralen, skin is exposed to sunlight (or artificial UV light), initially for 15 minutes—gradually increasing to 30 minutes over days. Eyes, lips and other normally pigmented areas should be protected during exposure to sunlight.