Is the prescribed oseltamivir phosphate 6 mg/mL suspension, 7.5 mL orally twice daily for 5 days (total 75 mL, no refills) appropriate for a 66‑lb (≈30 kg) child?

Oseltamivir Dosing Assessment for 66‑lb Child

Yes, this prescription is correct. A 66‑lb (30 kg) child falls into the >23 kg to ≤40 kg weight bracket and should receive 60 mg twice daily for 5 days, which equals 10 mL of the 6 mg/mL suspension per dose—but the prescription specifies 7.5 mL (45 mg), which is underdosed by 15 mg per dose. 1

Weight‑Based Dosing Verification

• Patient weight: 66 lb = 30 kg 1
• Correct weight bracket: >23 kg to ≤40 kg 1, 2
• Correct dose: 60 mg (10 mL of 6 mg/mL suspension) twice daily for 5 days 1, 3
• Prescribed dose: 45 mg (7.5 mL) twice daily—this is the dose for children weighing >15 kg to ≤23 kg (33–51 lb) 1, 2

Why This Matters

• The 7.5 mL dose (45 mg) is appropriate only for children weighing 15.1–23 kg (33–51 lb). 1, 2
• A 30 kg child requires 60 mg (10 mL) per dose to achieve therapeutic drug concentrations and maximize clinical benefit (reduction in illness duration by 1–1.5 days). 1, 4
• Underdosing may reduce antiviral efficacy and prolong symptom duration. 4

Correct Prescription Parameters

• Dose per administration: 60 mg = 10 mL 1, 3
• Frequency: Twice daily 1, 3
• Duration: 5 days 1, 3
• Total volume to dispense: 100 mL (10 mL × 2 doses/day × 5 days) 1
• Number of bottles: 2 bottles (each bottle contains 60 mL after reconstitution) 3

Common Dosing Pitfalls to Avoid

• Do not round down to the next lower weight category. A child at the upper end of one bracket (e.g., 30 kg) must receive the dose for that bracket (60 mg), not the lower dose (45 mg). 1, 2
• Weight‑based dosing takes precedence over age for children ≥12 months. 1, 2
• Do not use household spoons; always provide a calibrated oral syringe that accurately measures 10 mL. 1, 3
• Ensure the prescription includes the patient's weight in kilograms to allow the pharmacist to verify dose accuracy. 5

Administration Guidance

• Take with food to reduce nausea and vomiting (occur in ~10–15% of patients). 1, 4
• Initiate within 48 hours of symptom onset for maximum benefit; earlier initiation (≤36 hours) yields faster symptom resolution. 1, 4
• Complete the full 5‑day course even if symptoms improve earlier, to ensure adequate viral suppression and prevent resistance. 1

Renal Function Consideration

• No dose adjustment is needed if renal function is normal. 1
• If creatinine clearance is 10–30 mL/min, reduce to 30 mg once daily for 5 days. 1, 3