METHOTREXATE REVISITED - EFFECTS OF LONG-TERM TREATMENT IN PSORIASIS

In the past 22 years, 113 patients with severe psoriasis have been tre ated with low-dose methotrexate (MTX) in our department. The maximum w eekly dosage was 15 mg (Weinstein schedule), the estimated mean cumula tive dose was 4803 mg, and the estimated mean duration of therapy was 8 years and 11 months. In 81% of the patients, prolonged clearance or near clearance was achieved, indicating the potent and sustained poten tial of MTX in the treatment of both the pustular and erythematosquamo us variants of psoriasis. Eighty-three patients (73%) had side-effects , most frequently abnormal liver function tests, nausea and gastric co mplaints. Apart from hair loss in seven patients, there were no mucocu taneous side-effects, probably because of the low-dose treatment sched ule. In 71 patients MTX therapy was discontinued; in 33 patients becau se of side-effects. In 55 patients one or more liver biopsies were per formed. Fibrosis was seen in seven of these patients (13%) and cirrhos is in two (4%). There was no relation between liver biopsy classificat ion and cumulative dosage or duration of MTX therapy, nor was there an y relation between liver histology and abnormal liver function tests. During this 22-year period, there were no deaths or life-threatening s ide-effects attributable to MTX treatment. We conclude that low-dose M TX(less than or equal to 15 mg/week) is a relatively safe therapy for severe psoriasis, if patients are carefully selected beforehand, and r egular monitoring for side-effects and drug interactions is performed during therapy. A liver biopsy during the first 3 months of treatment, and subsequently after each 1.5 g of MTX, should be part of the treat ment protocol, until equally reliable non-invasive screening methods f or liver damage are developed.