Amoxicillin Dosage for Acute Otitis Media in a 57 kg Adult
For an adult weighing 57 kg with acute otitis media, the recommended dose of amoxicillin is 80-90 mg/kg/day, which equals 4560-5130 mg daily, divided into two doses. 1
Dosing Calculation and Rationale
The American Academy of Pediatrics (AAP) and American Academy of Family Physicians (AAFP) guidelines specifically recommend amoxicillin at a dosage of 80-90 mg/kg/day for acute otitis media 1. This higher dosage is designed to overcome resistant strains of Streptococcus pneumoniae, which is a common pathogen in otitis media.
For a 57 kg adult, this calculates to:
- 57 kg × 80 mg/kg = 4560 mg/day
- 57 kg × 90 mg/kg = 5130 mg/day
Administration Schedule
- Preferred regimen: Divide into two daily doses (every 12 hours)
- Morning dose: 2280-2565 mg
- Evening dose: 2280-2565 mg
This twice-daily regimen is supported by evidence showing comparable efficacy to three-times-daily dosing with significantly less diarrhea 2.
Practical Administration Options
Since standard amoxicillin tablets are typically available in 500 mg or 875 mg strengths, the following practical options exist:
Using 875 mg tablets:
- Take 3 tablets (2625 mg) twice daily
- This provides 5250 mg daily, which is slightly above the calculated range but clinically appropriate
Using 500 mg tablets:
- Take 5 tablets (2500 mg) twice daily
- This provides 5000 mg daily, which falls within the calculated range
Treatment Duration
The recommended duration of therapy for acute otitis media is 10 days 3.
Alternative Options
If the patient fails to respond to high-dose amoxicillin within 48-72 hours, consider switching to:
- Amoxicillin-clavulanate: 4 g/day of amoxicillin component with 250 mg of clavulanate 1
- Ceftriaxone: Intramuscular option for treatment failure 4
Monitoring and Follow-up
- Assess response to therapy within 48-72 hours
- If symptoms worsen or do not improve after 72 hours of treatment, reevaluate the diagnosis and consider changing antibiotics 1
- Monitor for adverse effects, particularly diarrhea, which is more common with higher doses
Important Considerations
- Resistance patterns: High-dose amoxicillin is recommended as first-line therapy in areas where drug-resistant S. pneumoniae is prevalent 5
- Viral co-infection: May reduce the efficacy of antibiotics; maintain the high-dose regimen 6
- Compliance: The twice-daily regimen improves compliance compared to more frequent dosing 7
Common Pitfalls to Avoid
Underdosing: Traditional adult amoxicillin dosing (1.5-1.75 g/day) is insufficient for treating acute otitis media, especially with resistant organisms 5
Inappropriate duration: Shorter courses may lead to treatment failure; complete the full 10-day course
Delayed switch to second-line therapy: If no improvement after 48-72 hours, promptly reassess and consider alternative antibiotics 1
Ignoring pain management: Address pain relief alongside antibiotic therapy, especially during the first 24 hours 1