Reported medication errors associated with methotrexate

Purpose. Medication errors reported to FDA as adverse events in which methotrexate was identified as a possible contributor were studied. Methods. All adverse-event reports submitted to FDA between November 1997 and December 2001 indicating potential medication errors involving methotrexate were analyzed to determine the indication for use, the type of error, and the point in the medication-use process where the error occurred. Results. A total of 106 cases of reported medication errors associated with methotrexate were identified, including errors resulting in 25 deaths (24%) and 48 other serious outcomes (45%). The most common types of errors involved confusion about the once-weekly dosage schedule (30%) and other dosage errors (22%). The most frequently involved indication for use was rheumatoid arthritis (42%). Of the errors, 39 (37%) were attributable to the prescriber, 21 (20%) to the patient, 20 (19%) to dispensing, and 18 (17%) to administration by a health care professional. Conclusion. A review of medication errors involving methotrexate revealed that errors occurred during all phases of use, often resulted from confusion about dosage, and often caused death or other serious adverse effects.