Counting Errors in a Busy Dispensary
You are checking a dispensing tray prepared by a junior colleague at a hospital outpatient pharmacy. The prescription is for a 65-year-old woman: 'Prednisolone 5 mg tablets - 40 mg daily for 5 days, then reduce by 5 mg every 3 days until stopped.' The tray contains 5 mg tablets. The colleague has calculated the total quantity as 60 tablets and written on the label 'take 8 tablets daily'. You also notice the patient's other prescription is for warfarin, and she has a documented peptic ulcer. The dispensary is short-staffed and there are 12 patients waiting.
1. Verify the total quantity of 5 mg prednisolone tablets required for the tapering course, showing the full calculation.
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The regimen is a step-down taper. Work through each step:
- 40 mg/day for 5 days = 8 tablets/day × 5 = 40 tablets
- 35 mg/day for 3 days = 7 × 3 = 21
- 30 mg/day for 3 days = 6 × 3 = 18
- 25 mg/day for 3 days = 5 × 3 = 15
- 20 mg/day for 3 days = 4 × 3 = 12
- 15 mg/day for 3 days = 3 × 3 = 9
- 10 mg/day for 3 days = 2 × 3 = 6
- 5 mg/day for 3 days = 1 × 3 = 3 Total = 40 + 21 + 18 + 15 + 12 + 9 + 6 + 3 = 124 tablets. The colleague's figure of 60 is wrong - it appears to have counted only the first phase plus a rough guess. The label 'take 8 tablets daily' is also wrong because it describes only the first step and would be dangerous if followed for the whole course. The label must state the full tapering schedule in words and figures, with dates or day ranges, and the patient must be counselled on it.
2. Beyond the arithmetic, what clinical safety issues does this patient raise, and how do you act with 12 patients waiting?
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Clinical issues:
- Warfarin interaction. Prednisolone can alter anticoagulant effect and increase gastrointestinal bleeding risk; the combination with a documented peptic ulcer is a significant concern. The pharmacist must review and the prescriber may need to adjust monitoring (INR) or add gastroprotection.
- Peptic ulcer. Systemic corticosteroids increase the risk of ulceration and bleeding, especially with an anticoagulant and in an older patient. Gastroprotection (e.g. a proton-pump inhibitor) should be considered by the prescriber.
- Taper labelling. A taper that is mislabelled is a genuine patient-safety event; abrupt cessation or wrong tapering can cause adrenal insufficiency. How to act under pressure: stop the tray from leaving the pharmacy. Correct the quantity and rewrite the label with the full schedule. Escalate to the pharmacist for the interaction review and, if needed, a call to the prescriber before the patient leaves. Tell the waiting patients honestly that there is a short delay. Speed must never override the final check - a 'near miss' caught at the checking bench is a success, not a failure. Record the near miss so the cause (calculation and labelling of tapers) can be addressed with training.