Weekly methotrexate is considered the cornerstone of therapy for rheumatoid arthritis. Methotrexate is also used as a steroid-sparing agent in a variety of other rheumatic diseases. It improves all clinical parameters of RA, including joint pain, swelling and function. It also slows the rate of radiographic progression of the disease.
What toxicities are associated with methotrexate use? How are patients monitored for methotrexate toxicity?
Side effects of methotrexate include fatigue, oral ulcers, nausea, vomiting, anorexia. Methotrexate is hepatotoxic and can cause myelosuppression. It is a teratogen. Pneumonitis and alopecia are rare complications of methotrexate use. Use of folic acid supplements reduces toxicity.
Before starting methotrexate, a baseline CBC, creatinine and liver enzymes should be performed. A chest x-ray along with hepatitis B and C serology should also be done. In women of child-bearing age, it is prudent to perform a B-HCG. Patients on methotrexate are monitored with liver enzymes and a CBC every 1 to 2 months.
What are the contraindications to methotrexate use?
Contraindications to methotrexate use include chronic liver disease and alcoholism. It can be used with caution and dose adjustment in patients with renal dysfunction. Relative contraindications include parenchymal lung disease and cytopenias.
Women of childbearing age should use effective contraception. Methotrexate should be held (in men as well as women) three months prior to attempting conception. Methotrexate is not used in nursing mothers.