Oral Equivalent to Unasyn (Ampicillin-Sulbactam)
Amoxicillin-clavulanate (Augmentin) is the oral antibiotic that provides equivalent coverage to intravenous Unasyn (ampicillin-sulbactam). 1
Rationale for Equivalence
- Both combinations pair a beta-lactam antibiotic with a beta-lactamase inhibitor, providing similar antimicrobial spectrum 1, 2
- Amoxicillin-clavulanate covers gram-positive organisms (including methicillin-sensitive Staphylococcus aureus and streptococci), gram-negative bacteria (including E. coli, Proteus, Klebsiella), and anaerobes (including Bacteroides fragilis and Clostridium species) 3, 1, 4
- This spectrum mirrors that of ampicillin-sulbactam, which is effective against the same range of pathogens 2, 5
Dosing Considerations
- Standard adult dosing: Amoxicillin-clavulanate 875 mg/125 mg orally twice daily or 500 mg/125 mg three times daily 1
- For more severe infections or resistant organisms: High-dose formulations (2000 mg/125 mg twice daily) may be necessary 6
- Pediatric dosing: 45 mg/kg/day of amoxicillin component for standard infections, or 90 mg/kg/day for resistant organisms 4
Clinical Applications Where This Transition Is Appropriate
- Skin and soft tissue infections: When transitioning from IV to oral therapy after clinical stability is achieved 6
- Intra-abdominal infections: For step-down therapy in mild-to-moderate infections 6, 2
- Respiratory tract infections: Including sinusitis and community-acquired pneumonia 6
- Urinary tract infections: For susceptible organisms 7, 2
- Diabetic foot infections: As oral continuation therapy 2
Important Caveats
Amoxicillin-clavulanate is NOT active against:
For MRSA coverage, if needed, add or substitute with: clindamycin, trimethoprim-sulfamethoxazole, doxycycline, or linezolid 6
Gastrointestinal side effects (particularly diarrhea) are the most common adverse effect of amoxicillin-clavulanate 2