[Methotrexate in rheumatoid arthritis].

Methotrexate may be effective in patients with rheumatoid arthritis refractory to other treatments (gold salts, d-penicillamine and antimalarial drugs). Success rates from 39 to 88% have been reported. The mechanism of action is unknown, but is supposedly related to anti-inflammatory and immunosuppressive effects. Frequent side effects are observed on prolonged treatment. Most of these are mild and disappear with dose reduction. An exception is pneumonitis, a hypersensitivity reaction that may appear early and at low doses. Hepatotoxic effects are milder than those observed in patients with psoriasis. Intraarticular administration is not effective. No carcinogenic effects have been observed in humans. The drug should be administered with caution in fertile males and females due to possible teratogenic effects. New studies involving larger number of patients may help establish a significant role for methotrexate in the treatment of rheumatoid arthritis.