What is the dosage of Augmentin (amoxicillin-clavulanate) liquid form for acute bacterial rhinosinusitis in a patient who has failed amoxicillin treatment?

High-Dose Augmentin Liquid for Failed Amoxicillin in Acute Bacterial Rhinosinusitis

For adults who have failed amoxicillin treatment for acute bacterial rhinosinusitis, prescribe high-dose Augmentin liquid: 2000 mg amoxicillin/125 mg clavulanate twice daily for 5-7 days. 1

Rationale for High-Dose Therapy

Amoxicillin failure indicates likely resistant pathogens, particularly beta-lactamase-producing organisms or penicillin-resistant Streptococcus pneumoniae, which require the high-dose formulation. 1 The high-dose regimen achieves 90-92% predicted clinical efficacy compared to only 83-88% for standard-dose therapy. 1

Recent antibiotic exposure (within 4-6 weeks) is a major risk factor for antimicrobial-resistant strains, making high-dose therapy essential in treatment failures. 1

Specific Liquid Dosing Instructions

Adults

• Amoxicillin component: 2000 mg (total) twice daily
• Clavulanate component: 125 mg twice daily
• Duration: 5-7 days 1

The liquid formulation must deliver these exact amounts - do not substitute two 250 mg doses for one 500 mg dose, as this results in excessive clavulanate and increased gastrointestinal side effects. 2

Pediatric Dosing (if applicable)

• High-dose: 90 mg/kg/day amoxicillin with 6.4 mg/kg/day clavulanate, divided into 2 doses
• Maximum: 4000 mg amoxicillin per day 1

Critical Reassessment Timeline

Evaluate clinical response at 72 hours. 1 If no improvement or worsening occurs:

• Switch to a respiratory fluoroquinolone (levofloxacin or moxifloxacin) 1
• Consider alternative diagnoses with imaging (CT scan) or cultures 1, 3
• Evaluate for complications requiring specialist referral 1

Alternative Options for High-Dose Failures

If high-dose Augmentin fails after 72 hours, consider:

• Respiratory fluoroquinolones (gatifloxacin, levofloxacin, moxifloxacin) - 90-92% predicted efficacy 1
• Ceftriaxone 1-2 g IV/IM daily for 5 days for patients unable to tolerate oral therapy 1

Common Pitfalls to Avoid

Do not use standard-dose Augmentin (875/125 mg or 500/125 mg) for amoxicillin failures - this provides inadequate coverage for resistant pathogens and perpetuates treatment failure. 1

Do not extend treatment beyond 7 days initially - if symptoms persist at day 7, this represents treatment failure requiring alternative antibiotics, not longer duration of the same agent. 1

Monitor for diarrhea - occurs in 40-44% of patients on Augmentin, with severe diarrhea in approximately 7-8%. 4 The high-dose formulation uses a 14:1 ratio of amoxicillin to clavulanate, which minimizes this risk compared to other formulations. 3

Renal Dosing Adjustments

For patients with severe renal impairment (GFR <30 mL/min):

• GFR 10-30 mL/min: 250-500 mg every 12 hours
• GFR <10 mL/min: 250-500 mg every 24 hours 2

Supporting Evidence for High-Dose Efficacy

The high-dose formulation achieves superior tissue penetration in sinus cavities, with tissue inhibitory quotients exceeding those required for pneumococcal eradication. 5 Clinical studies demonstrate 93-97.3% success rates against S. pneumoniae, including penicillin-resistant strains with MICs up to 4/2 mcg/ml. 6

Note: Recent high-quality evidence suggests that even high-dose therapy may provide minimal benefit over placebo in clinically diagnosed acute sinusitis 4, but when antibiotics are deemed necessary for treatment failures with concerning features (high fever, severe symptoms, immunocompromise), high-dose Augmentin remains the guideline-recommended choice over standard dosing. 1