Pediatric Amoxicillin: Dose and Quantity Check
A 3-year-old boy, weight 15 kg, is diagnosed with acute otitis media at an urgent care clinic. The e-prescription reads: amoxicillin 400 mg/5 mL suspension, 5 mL PO twice daily for 10 days, dispense 100 mL. He has no allergies and normal renal function. He took amoxicillin 6 weeks ago for the same indication. The pharmacy has 400 mg/5 mL suspension in 50 mL, 75 mL, and 100 mL bottles. The prescription is otherwise complete and the prescriber is reachable. The parent asks whether the dose is correct because the child weighs more than his 4-year-old sibling.
1. Calculate the prescribed mg/kg/day and compare it with usual AOM dosing. What should you do?
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The concentration is 400 mg/5 mL = 80 mg/mL. A 5 mL dose contains 400 mg. Twice daily gives 800 mg/day. Divide by 15 kg: 800 ÷ 15 = 53.3 mg/kg/day. For acute otitis media, high-dose amoxicillin is commonly 80–90 mg/kg/day divided twice daily, especially with recent amoxicillin exposure or severe symptoms; standard dosing may be lower in selected cases. This prescription is below the high-dose range. Do not dispense until you clarify with the prescriber. A reasonable correction is 7.5 mL PO BID, which provides 600 mg/dose, 1200 mg/day, or 80 mg/kg/day. Document the calculation and the prescriber’s response.
2. If the prescriber changes to 7.5 mL BID x10 days, what quantity and bottle size should be dispensed?
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Total volume = 7.5 mL × 2 doses/day × 10 days = 150 mL. The pharmacy has 50 mL, 75 mL, and 100 mL bottles, so dispense two 75 mL bottles (or one 100 mL plus one 50 mL bottle) to provide 150 mL. Do not dispense only 100 mL, because that would be a 6.7-day supply and the patient would run out early. Label with the new dose, shake well, and assign a beyond-use date according to the manufacturer and pharmacy policy (commonly 14 days for reconstituted amoxicillin suspension).
3. What counseling points and documentation are needed?
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Counsel the parent to shake the suspension well before each dose, measure with an oral syringe rather than a household spoon, and complete the full 10-day course even if the child improves. Review common adverse effects (diarrhea, rash) and when to call (hives, facial swelling, severe diarrhea, persistent fever). Discuss storage and discard date. Document the original prescription, the dose calculation, the prescriber clarification, the new quantity, and the counseling. If the prescriber cannot be reached, do not dispense the unclarified dose; offer to hold the prescription and contact the parent when resolved.