What is the recommended dosage of amoxicillin (amoxicillin) for acute otitis media in a patient weighing 51.5kg?

Amoxicillin Dosing for Acute Otitis Media in a 51.5kg Patient

For a patient weighing 51.5kg with acute otitis media, prescribe amoxicillin 500 mg three times daily (1,500 mg total daily dose) for 10 days. 1

Weight-Based Dosing Considerations

• Adults and adolescents weighing ≥45.5 kg should receive 500 mg three times daily, which is the standard adult dosing regimen for acute otitis media 1
• This patient at 51.5 kg exceeds the 45.5 kg threshold where pediatric weight-based dosing transitions to fixed adult dosing 1
• The high-dose pediatric regimen of 80-90 mg/kg/day is specifically designed for children and would result in an unnecessarily high dose (4,120-4,635 mg/day) that exceeds standard adult recommendations 2, 3

Rationale for Standard Adult Dosing

• The 500 mg three times daily regimen (1,500 mg/day total) is appropriate for uncomplicated acute otitis media in patients of this weight 1
• This dosing provides adequate coverage against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, the primary pathogens in acute otitis media 4
• Penicillin has never demonstrated resistance among S. pneumoniae strains, supporting its continued use as first-line therapy 1

Alternative Dosing for Higher Risk Scenarios

• If the patient has received antibiotics within the past 30 days, has severe illness, or lives in an area with >10% penicillin-nonsusceptible S. pneumoniae, consider high-dose amoxicillin-clavulanate (875 mg/125 mg twice daily) instead 1
• Risk factors warranting broader coverage include recent antimicrobial exposure within 4-6 weeks, moderate-to-severe disease presentation, or treatment failure at 72 hours 1, 3

Treatment Duration and Monitoring

• Complete a full 10-day course of therapy, even if symptoms resolve earlier 1
• The patient becomes non-contagious after 24 hours of antibiotic therapy 1
• Reassess if symptoms worsen or fail to improve within 48-72 hours, which may indicate treatment failure requiring a switch to amoxicillin-clavulanate or alternative agent 1, 3

Common Pitfalls to Avoid

• Do not apply pediatric high-dose calculations (80-90 mg/kg/day) to patients weighing >45.5 kg, as this results in excessive dosing beyond established adult regimens 1, 2
• Avoid using amoxicillin-clavulanate as first-line therapy unless specific risk factors are present, as unnecessary clavulanate increases adverse effects without added benefit in uncomplicated cases 3
• Do not prescribe twice-daily dosing for standard amoxicillin in acute otitis media; the established regimen is three times daily 1