Polymyositis and Dermatomyositis: Combined Methotrexate and Corticosteroid Therapy

Twenty-two patients with polymyositis and dermatomyositis were treated with combined prednisone and intravenous methotrexate when moderate to high-dose cortisone alone was ineffective in controlling disease activity. Definite clinical improvement was noted in 17 or 77% of the patients. Those patients responding to therapy normalized their muscle enzymes (creatine Phosphokinase, CPK) after a mean period of 10 weeks; moreover, the onset of muscle strength improvement was noted at an average of 13 weeks. A "steroid-sparing" effect was noted in that the prednisone dose has been decreased from 47 mg/day (premethotrexate) to 12 mg/day at 15 months follow-up. Toxicity to methotrexate was minor and reversible. After an average treatment period of more than 1 year, and a total average dose of over 1 g methotrexate, clinical and laboratory hepatotoxicity was not found. Intravenous methotrexate is an important treatment for polymyositis and dermatomyositis.