Severe recalcitrant rheumatoid arthritis or polyarticular-course juvenile rheumatoid arthritis.
Initially 7.5mg once per week as a single dose, or a course of three 2.5mg doses at 12-hour intervals once per week; max 20mg/week. May give test dose first.
<2yrs: not recommended. ≥2yrs: initially 10mg/m2 once weekly; max 20mg/m2 per week.
DMARD (folic acid antagonist).
Immunodeficiency. Blood dyscrasias. Alcoholism. Chronic liver disease. Pregnancy (Cat.X). Nursing mothers.
Be fully familiar with this drug's toxicity before use. Discontinue if malignant lymphomas occur. Obtain baseline and monitor CBCs with differential, platelet counts, chest X-ray, and hepatic, renal and pulmonary function. During therapy monitor hematology monthly, renal and hepatic function every 1–2 months, more often if increasing dose or predisposed to toxicity (eg, dehydration). Discontinue immediately if blood counts drop significantly. Rule out pregnancy in women of childbearing potential; use effective contraception during therapy and for at least 1 ovulatory cycle afterwards for women and for at least 3 months afterwards for men. Interrupt therapy if vomiting, diarrhea, stomatitis, or pulmonary symptoms occur. Hepatic or renal impairment. Obesity. Diabetes. Peptic ulcer. Ulcerative colitis. Infection. Dehydration. Folate deficiency. Ascites, pleural effusions: evacuate fluid, monitor for toxicity and reduce dose or discontinue if needed. Elderly (use low doses and monitor closely). Debilitated.
Avoid other hepatotoxic drugs, live virus vaccines. Caution with nephrotoxic agents. Toxicity increased by NSAIDs, salicylates, phenytoin, sulfonylureas, sulfonamides, probenecid, penicillins (monitor), tetracyclines, chloramphenicol, non-absorbable broad spectrum antibiotics, folic acid antagonists. Impaired response to immunization. May potentiate theophylline. Antagonized by folic acid. Radiotherapy increases risk of soft tissue necrosis, osteonecrosis. Recall reactions after UV radiation.
Elevated liver enzymes, nausea, vomiting, stomatitis, thrombocytopenia, rash, pruritus, dermatitis, diarrhea, alopecia, leukopenia, pancytopenia, dizziness, hepatoxicity, bone marrow suppression, GI toxicity, fibrosis, cirrhosis, tumor lysis syndrome, fatal skin reactions, opportunistic infections, cough, chest lesions.
Tabs 2.5mg (4-card dose pack)—5mg/week, 7.5mg/week, 10mg/week, 12.5mg/week, 15mg/week