Methotrexate therapy in connective tissue diseases: a review of the literature.

Low dose methotrexate (MTX) therapy is now widely used with considerable success in refractory rheumatoid arthritis. Experience with the drug in other connective tissue diseases and vasculitis has been limited. This article reviews hypotheses about the mode of action of MTX, pharmacology and pharmacokinetics, reasons to use cytotoxic agents in the different diseases, and results of MTX therapy. Risk factors, adverse reactions and drug interactions of MTX with other drugs are mentioned. Although based on a small number of patients, data about remarkable clinical improvement in polymyositis, systemic lupus erythematosus and vasculitis suggest that MTX is a potent and effective drug in connective tissue diseases other than rheumatoid arthritis. However, controlled trials are needed to assess the exact value of the drug in these diseases.