The Pediatric Antibiotic and the Wrong Concentration
A pharmacist receives an electronic prescription for amoxicillin 400 mg/5 mL suspension, 5 mL by mouth three times daily for 10 days, for a 4-year-old child weighing 16 kg. The prescription is for 150 mL. The pharmacy stocks amoxicillin 250 mg/5 mL suspension. The pharmacist calculates the dose: 400 mg/5 mL × 5 mL = 400 mg per dose, three times daily = 1200 mg/day, or 75 mg/kg/day. The recommended dose for this indication is 80–90 mg/kg/day divided twice daily. The prescriber is unavailable, and the parent is waiting.
1. Is the prescribed dose appropriate, and what should the pharmacist do?
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The prescribed dose is 75 mg/kg/day divided three times daily. The recommended dose for this indication is 80–90 mg/kg/day divided twice daily, so the prescribed dose is below the recommended range and the dosing interval is not the recommended one. The pharmacist should not simply dispense. The pharmacist should attempt to reach the prescriber to clarify the dose and interval. If the prescriber cannot be reached, the pharmacist should consider whether the prescription is safe and effective as written. Because the dose is below the recommended range, the pharmacist should not substitute a different concentration without prescriber authorization.
2. The pharmacy only stocks 250 mg/5 mL. Can the pharmacist substitute that concentration?
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No. Substituting a different concentration changes the volume the patient must measure and can lead to dosing errors. The pharmacist may not change the concentration without prescriber authorization. If the pharmacist cannot reach the prescriber, the pharmacist should not dispense a different concentration. The pharmacist could contact another pharmacy to obtain the prescribed concentration, or ask the parent to wait while the prescriber is contacted. The pharmacist should document the attempt and the decision.
3. What counseling points are essential when the correct product is dispensed?
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The pharmacist should counsel the parent on: the correct volume per dose using the dosing device provided (not a kitchen spoon); the frequency and duration; shaking the suspension well; refrigerating the suspension (if required by the product) and discarding after the labeled period; completing the full course; recognizing adverse effects (diarrhea, rash, allergic reaction); and when to call the prescriber. The pharmacist should also verify the child's weight and confirm the dose calculation with the parent, and document the counseling.