To the Editor.
—We have systematically evaluated prescribing errors for the past 6 years.1 Recently, we have observed recurrent prescribing errors involving methotrexate for rheumatoid arthritis. Treatment with methotrexate for rheumatoid arthritis usually involves a regimen of onceweekly administration of doses ranging from 2.5 to 35 mg.2,3 Daily administration of methotrexate greatly increases the potential for toxic effects from a given dose, as it does not allow an interval for the cellular recovery from methotrexate depletion of tetrahydrofolate.4 Significant toxic effects have been reported following daily administration of methotrexate (for as little as 4 days) because of medication errors.4,5In the past year we observed five patients (three inpatients and two outpatients) for whom methotrexate prescribing errors occurred. Inpatient 1 was admitted acutely for unstable angina and eventually underwent coronary bypass grafting. His preadmission medications included 7.5 mg of methotrexate once weekly. During his hospitalization, he was
Lomaestro BM, Lesar TS, Hager TP. Errors in Prescribing Methotrexate. JAMA. 1992;268(15):2031–2032. doi:10.1001/jama.1992.03490150083021