Methotrexate

Abstract

Methotrexate is the most widely used antipsoriatic therapy since 1951 because of the effectiveness and the inexpensive cost. Methotrexate is indicated in moderate to severe psoriasis and is administered either by single oral or single intramuscular weekly dose or as intermittent oral schedule of three divided doses over a 36 hour period once a week. The doses are 7.5-25 mg per week. The common acute side effects are GI upset, malaise, headache, oral ulceration and myelosuppression. Overdosage is seen in patients with decreased renal function. The most serious long-term side effect is liver cirrhosis. Liver enzyme may be elevated during taking methotrexate but may be not totally reflective the developing of liver pathology.

Liver biopsy is the most definite monitoring procedure to be performed after 1.5 gm accumulative doses have been reached. But in Thailand, the liver biopsy is rarely done because both patient and physician do not want to take the complication risks. Methotrexate is still the essential drug for psoriasis in the developing country. Low incidence of liver cirrhosis is reported may be due to the difference in genetic background and less alcohol consumption in Thai psoriatic patients.