A family physician's guide to monitoring methotrexate

Methotrexate has a long history of use in the treatment of various immunolo gic diseases, including rheumatoid arthritis and psoriasis, Although the dr ug is usually prescribed by a subspecialist, a family physician may assume responsibility for monitoring methotrexate therapy. Major toxic effects, su ch as hepatic. pulmonary. renal and bone marrow abnormalities, require care ful monitoring. Minor toxic effects, such as stomatitis, malaise, nausea, d iarrhea. headaches and mild alopecia, are common but respond to folate supp lementation. Methotrexate is administered once weekly as a single dose or i n divided doses given over a 24-hour period. To reduce the incidence of maj or toxic: effects, methotrexate should never be given in daily doses. Relat ive contraindications include renal dysfunction, liver disease, active infe ctious disease and excessive alcohol consumption. Both women and men of rep roductive age should use birth control during methotrexate therapy. Potenti al drug interactions include salicylates and nonsteroidal anti-inflammatory drugs, which are both commonly used in patients with rheumatoid arthritis or psoriasis, A premethotrexate evaluation is important to ensure proper pa tient selection for this effective but potentially toxic drug.