Methotrexate Ordered Daily Instead of Weekly
A 72-year-old woman with rheumatoid arthritis and normal renal function is seen by a new rheumatologist. She brings a new e-prescription to your pharmacy: methotrexate 2.5 mg tablets, take 1 tablet PO every morning for arthritis, quantity 30, 0 refills. She says her previous doctor told her to take methotrexate once a week, but she thinks the new label is different. She also takes folic acid 1 mg daily and ibuprofen 400 mg PRN. The prescription was transmitted through the e-prescribing system and appears authentic. The prescriber's office is closed for the weekend; an on-call covering physician is available by phone.
1. What is the problem and what should you do before dispensing?
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Methotrexate for rheumatoid arthritis is dosed weekly, not daily. Daily methotrexate is a well-known fatal medication error. Do not dispense the prescription as written. Call the on-call covering physician, explain the prescription says 'every morning,' and request clarification. If weekly dosing is confirmed, the prescriber must issue or authorize a corrected prescription; do not change the directions on your own. Counsel the patient not to take any dose from the new bottle until the schedule is confirmed. Document the conversation, the original directions, and the corrected directions.
2. If the prescriber confirms weekly dosing, how should the label and counseling be managed?
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Label the prescription with a specific weekly day, e.g., 'Take 1 tablet (2.5 mg) by mouth once weekly on Sunday,' not merely 'once weekly.' Quantity 30 is a 30-week supply. Provide a written calendar and ask the patient to repeat back the schedule. Warn that the dose is weekly, not daily, and that folic acid is taken daily. Review signs of toxicity: mouth sores, fever, bruising, shortness of breath, nausea, and dark urine. Advise avoiding alcohol and new NSAIDs without checking, and confirm monitoring of CBC, liver enzymes, and renal function. Document the counseling.
3. What system safeguards should the pharmacy implement?
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Build a hard stop or hard warning in the pharmacy system for methotrexate directions containing 'daily,' 'BID,' or 'TID,' and default the sig to weekly. Add an auxiliary label stating 'WEEKLY-NOT DAILY' and store methotrexate with high-alert medications. Require an independent double-check of the directions at final verification. Educate staff and prescribers about the error, and report it through the ISMP Medication Errors Reporting Program. At the patient level, use teach-back and a day-of-week chart. Audit methotrexate prescriptions monthly to confirm that directions are weekly and that the quantity matches the intended duration.