Case Study 4: A Methotrexate Dispensing Error Discovered After Harm
A 72-year-old woman with rheumatoid arthritis brings a repeat prescription to a busy pharmacy in Kwun Tong. The prescription is for methotrexate 2.5 mg tablets, 'take ONE tablet WEEKLY', with folic acid 5 mg on the other six days. The pharmacist, distracted by a queue, enters the directions as 'take ONE tablet DAILY' and dispenses 28 tablets with a printed label saying daily. The patient takes one tablet daily for five days. She returns on day 6 with mouth ulcers, bruising on both forearms and a temperature of 37.8 °C. The pharmacist realises the error when checking the repeat. The patient lives alone and her daughter is away. The pharmacy has no written error-reporting policy.
1. What immediate clinical and professional actions should the pharmacist take?
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The pharmacist must put the patient's safety first and act immediately.
- Stop the methotrexate. Tell the patient clearly not to take any more tablets.
- Arrange same-day urgent medical assessment, such as the nearest accident and emergency department, because daily methotrexate can cause serious toxicity. Mouth ulcers, bruising and fever are warning signs.
- Contact the prescriber or the patient's usual doctor and explain the error, the dose taken and the patient's symptoms.
- Give the patient a written summary of what happened, the medicine and directions, and where she is being referred.
- Do not leave the patient to arrange transport alone if she is unwell; help her contact a family member or arrange safe transport.
- Be honest and apologise for the error. Do not minimise it or blame the patient.
- Follow up to find out the clinical outcome.
2. What legal issues arise under Cap. 138 and the labelling requirements?
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Methotrexate is a Part 1 poison with a narrow therapeutic index. Several legal issues arise:
- The medicine was supplied on a prescription but not in accordance with the prescriber's directions. The label said daily instead of weekly.
- The labelling requirements for poisons require the label to correspond accurately to the prescription and to include the required particulars and warnings. A mislabelled poison is a serious contravention.
- The supply was made by a registered pharmacist in a registered pharmacy, but the dispensing process failed. Registration does not excuse a dispensing error.
- The pharmacist should preserve the prescription, the dispensed label, the stock and the patient's returned medicines as evidence for review. Do not alter the label retrospectively.
- The pharmacist should seek advice on whether the error is notifiable to the Pharmacy and Poisons Board or other authorities. Even if reporting is not mandatory in every case, concealment would be professionally worse.
3. How should the error be documented and reported?
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Document the following in a factual incident report:
- patient details, prescriber and prescription;
- the medicine, strength, quantity and the incorrect directions printed;
- the date and time of dispensing and the dates the patient took the medicine;
- symptoms reported and actions taken, including referral and prescriber contact;
- who was involved and what was said to the patient;
- immediate corrective action and follow-up.
Report internally to the pharmacy owner or superintendent. Review the workflow that allowed the error: queue distraction, lack of a second check, ambiguous directions and absence of an error-reporting policy. Introduce a repeat-prescription check, a 'weekly' alert for methotrexate, and a no-blame reporting culture. The patient should receive a copy of the incident summary if appropriate, and the prescriber should be informed.