Photochemotherapy for psoriasis with orally administered methoxsalen.

Photochemotherapy denotes a therapeutic approach that is based on the interaction of light and a photoactive drug. This study describes the efficacy of photochemotherapy, using orally administered methoxsalen and long-wave ultraviolet light in 91 patients with severe, generalized psoriasis. Oral administration of methoxsalen was followed by exposure to a high-intensity long-wave ultraviolet light source, emitting a continuous spectrum between 320 and 390 nm (peak, 365 nm) and an energy of 5.6 to 7.5 mw/sq cm at 15 cm. There was complete clearing of 82 patients (90%), a 90% to 100% clearing in seven (8%), and a satisfactory improvement in two (2%). A paired comparison study in 54 patients showed photochemotherapy to be far more effective than ultraviolet light emitted by fluorescent bulbs or a xenon source. Eighty-five percent of the patients receiving outpatient maintenance treatment have remained in remission for periods up to 400 days.