Preliminary report of higher dose methotrexate treatment in juvenile rheumatoid arthritis.

Methotrexate (MTX) is widely used to treat juvenile rheumatoid arthritis (JRA). Although most patients respond to lower doses (0.15-0.5 mg/kg/wk), some patients have required higher doses of MTX to control their arthritis. Thirteen children were treated with MTX 0.82-1.1 mg/kg/wk for 2-26 months. Although all children initially responded (> 50% improvement in joint index, erythrocyte sedimentation rate, morning stiffness and global evaluation), 4 patients discontinued treatment because of side effects or lack of prolonged efficacy. Five patients have continued taking higher dose MTX for 4-26 months, while 4 other patients have been able to decrease their MTX dose and maintain improvement. Twenty-four hour MTX levels were done on all patients at initiation of higher dose MTX and all cleared MTX well. Our report suggests that MTX in doses of 0.82-1.1 mg/kg/wk can successfully treat active synovitis in some children with severe JRA with few short term toxicities. Longterm use at these doses has not been studied and thus its safety is not known.