Combined methotrexate--ultraviolet B therapy in the treatment of psoriasis

Twenty-six patients with extensive psoriasis were treated with a 3-week course of methotrexate followed by a combination of ultraviolet B (UVB) therapy and methotrexate. A plaque of psoriasis was shielded during UV therapy to serve as a control. When lesions cleared to less than 5% of body involvement, the methotrexate was stopped and UVB therapy alone was used as maintenance therapy. This protocol achieved clearance of disease in all twenty-six patients in a mean of 7 (+/- 1.5) weeks, with twelve (+/- 4.0) exposures to UVB therapy and a final UVB radiation dose at clearance of 320 (+/- 157) mjoules/cm2. The mean total dose of methotrexate was 112 mg (range, 75 mg-165 mg). At the time of clearing, the shielded area had a decrease in sealing and thickness in twenty-two patients but was free of psoriasis in only four patients. In a preliminary study we were unable to reproduce a methotrexate recall of UV-induced erythema. The combination therapy of methotrexate and UVB allows for clearing of psoriasis at relatively low doses of UVB and methotrexate, and thus may reduce the long-term cumulative toxicity of both agents.