Methotrexate for Psoriasis

Therapy of patients with severe psoriasis has been facilitated in recent years by the use of systemic methotrexate. Several common schedules for drug administration include small daily oral doses and weekly intramuscular or oral doses. These schedules were empirically designed and have had reasonably good results. A new schedule of methotrexate administration is recommended for the treatment of psoriasis, based on current knowledge concerning the epidermal cell proliferation kinetics of psoriasis and chemotherapy with cell-cycle specific drugs. Methotrexate was administered orally in small doses (2.5 to 7.5 mg) at 12-hour intervals for a total of three doses at weekly intervals. Of 26 patients with severe psoriasis, 20 attained 75% to 100% improvement with administration of methotrexate. Side effects were minimal. The pharmacologic rationale for this drug schedule and its value relative to other commonly used schedules is discussed. Consideration of potential long-term risks with methotrexate must still be considered when evaluating patients for therapy.