What is the recommended dose of Augmentin (amoxicillin-clavulanate) for an adult patient with acute bacterial sinusitis?

Augmentin Dosing for Acute Bacterial Sinusitis in Adults

For adults with acute bacterial sinusitis, prescribe Augmentin 875 mg/125 mg twice daily for 5-10 days as the standard dose, or escalate to high-dose Augmentin 2000 mg/125 mg twice daily if risk factors for resistant organisms are present. 1, 2

Standard Dosing Algorithm

For uncomplicated cases without risk factors:

• Augmentin 875 mg/125 mg twice daily for 5-10 days 1, 3, 2
• The FDA label confirms this as the standard dose for respiratory tract infections 2
• Treatment duration of 5-7 days is as effective as 10 days in most cases 4
• Continue antibiotics until symptom-free for 7 days 1, 3

For cases with risk factors requiring high-dose therapy:

• Augmentin 2000 mg/125 mg (extended-release) twice daily 1, 4
• This provides 90-92% predicted clinical efficacy versus 83-88% for standard dosing 1, 4

Risk Factors Requiring High-Dose Therapy

Escalate to high-dose formulation when any of the following are present:

• Recent antibiotic use within the past 4-6 weeks 1, 4
• Moderate-to-severe disease presentation 1, 4
• Previous treatment failure with amoxicillin alone 1, 3
• Geographic areas with >10% prevalence of penicillin-resistant Streptococcus pneumoniae 1, 4
• High prevalence of β-lactamase-producing Haemophilus influenzae 1, 3
• Frontal or sphenoidal sinusitis 4
• Age over 65 years 4
• Immunocompromised status or significant comorbidities 4

Treatment Response Assessment

Evaluate clinical response at 72 hours (3 days):

• If no improvement or worsening occurs, switch to an alternative antibiotic or reevaluate the diagnosis 1, 4
• Consider imaging (CT scan), cultures, or endoscopy for complicated cases 4, 3
• Reassess to confirm bacterial sinusitis, exclude other causes, and detect complications 3

Evidence Quality Considerations

The recommendation for standard dosing is strongly supported by FDA labeling 2 and multiple guideline organizations 1, 4, 3. However, the evidence for high-dose therapy is mixed: one randomized trial found that immediate-release high-dose amoxicillin (1750 mg twice daily) provided 18% greater improvement at day 3 compared to standard dose (52.4% vs 34.4%, P=0.04) 5, but a subsequent larger trial found no benefit of high-dose therapy (36.4% vs 44.3% improvement, P=0.35) and was stopped for futility 6. Despite this conflicting research evidence, guidelines consistently recommend high-dose therapy for patients with risk factors 1, 4, likely based on pharmacokinetic/pharmacodynamic modeling showing superior coverage of resistant organisms 1, 7.

Alternatives for Penicillin-Allergic Patients

If penicillin allergy is present:

• Doxycycline or respiratory fluoroquinolones (levofloxacin, moxifloxacin) for severe cases 1, 3
• These alternatives have 20-25% bacteriologic failure rates 1
• Reserve fluoroquinolones for situations where major complications are likely or after first-line therapy failure 3

Critical Pitfalls to Avoid

Do not prescribe antibiotics for viral sinusitis:

• Antibiotics provide no benefit for post-viral acute rhinosinusitis and cause more adverse events 1, 8
• Only prescribe for true bacterial sinusitis meeting IDSA diagnostic criteria 1, 3

Adverse effects increase with high-dose therapy:

• Severe diarrhea occurs in 7-16% of patients on high-dose versus 5-7% on standard dose 5, 6
• Any diarrhea is reported in 40-43% of patients 6
• Gastrointestinal disturbances are the most common side effect 8, 9