methoxsalen /methok″sələn/ , a pigmentation agent. Also called 8-MOP. ▪ INDICATIONS: It is used topically for unresponsive psoriasis and enhancement of pigmentation or for repigmentation in vitiligo and is administered orally before long-wave ultraviolet irradiation of severe recalcitrant psoriasis. ▪ CONTRAINDICATIONS: Liver impairment, cataracts, age under 12 years, any disease or concomitant use of a drug that may cause photosensitization, squamous cell carcinoma, or known hypersensitivity to this drug prohibits its use. ▪ ADVERSE EFFECTS: Among the most serious adverse reactions are central nervous system effects and burns. Gastrointestinal discomfort and allergic reactions also may occur.