Joseph A. Govert, MD; Suzanne Patton, MD, PhD; Robert L. Fine, MD
To the Editors: Methotrexate is currently used for the treatment of psoriasis, asthma, rheumatoid arthritis, and cancer. Hazardous interactions may occur when combined with other drugs whose mechanism of action involves the same biochemical pathway. One such rarely described interaction is between low-dose, oral methotrexate and the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX) resulting in marrow hypoplasia (1-3).
A 58-year-old, white man with a long history of rheumatoid arthritis presented with symptoms and signs of prostatitis. His arthritis had been successfully managed with oral methotrexate, 7.5 mg weekly since 1988. A complete blood count showed a hemoglobin of 133 g/L, a hematocrit of
Govert JA, Patton S, Fine RL. Pancytopenia from Using Trimethoprim and Methotrexate. Ann Intern Med. ;117:877–878. doi: 10.7326/0003-4819-117-10-877_2
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Published: Ann Intern Med. 1992;117(10):877-878.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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