A 3-year-old child, weighing 15 kg, is prescribed acetaminophen 160 mg PO every 4-6 hours PRN for fever. The pharmacy has 160 mg/5 mL acetaminophen suspension available. The maximum recommended daily dose for acetaminophen in children is 75 mg/kg/day. The parent asks the pharmacist, "How much should I give, and how often?" What is the maximum volume per dose and the maximum number of doses per day the pharmacist should recommend, adhering to safety guidelines and the prescription?

Question: A 3-year-old child, weighing 15 kg, is prescribed acetaminophen 160 mg PO every 4-6 hours PRN for fever. The pharmacy has 160 mg/5 mL acetaminophen suspension available. The maximum recommended daily dose for acetaminophen in children is 75 mg/kg/day. The parent asks the pharmacist, "How much should I give, and how often?" What is the maximum volume per dose and the maximum number of doses per day the pharmacist should recommend, adhering to safety guidelines and the prescription?

Answer options:

• 5 mL every 4 hours, maximum 6 doses per day.
• 2.5 mL every 4 hours, maximum 5 doses per day. ✅ 5 mL every 6 hours, maximum 4 doses per day.
• 3.5 mL every 4 hours, maximum 4 doses per day.

Correct answer: 5 mL every 6 hours, maximum 4 doses per day.

Explanation: Each '160 mg' dose is 5 mL. At 160 mg/dose, 6 doses would exceed the maximum daily dose (160 mg x 6 = 960 mg). The maximum daily dose for a 15 kg child is 75 mg/kg x 15 kg = 1125 mg. However, a common recommendation for acetaminophen is a maximum of 4 doses in 24 hours to avoid exceeding limits and ensure appropriate spacing, consistent with the 'every 4-6 hours' PRN instructions. Giving 5 mL (160 mg) every 6 hours (total 640 mg/day) safely falls within the prescribed 'PRN every 4-6 hours' and below the maximum daily dose.