Recommended Dosage of Ampicillin-Sulbactam
The recommended adult dosage of ampicillin-sulbactam is 1.5 to 3 grams (1-2 grams ampicillin plus 0.5-1 gram sulbactam) administered intravenously every 6 hours, with the total daily sulbactam dose not exceeding 4 grams. 1
Adult Dosing Guidelines
Standard Dosing
- 1.5-3 grams IV every 6 hours (corresponds to 1g ampicillin/0.5g sulbactam to 2g ampicillin/1g sulbactam) 1
- Administration options:
Indication-Specific Dosing
- Culture-negative endocarditis (native valve): 12g/day IV in 4 equally divided doses (3g every 6 hours) plus gentamicin for 4-6 weeks 2
- Severe infections (including Acinetobacter baumannii): 9-12g/day of sulbactam in 3 daily doses 2
Renal Impairment Adjustments
| Creatinine Clearance (mL/min/1.73m²) | Half-Life (Hours) | Recommended Dosage |
|---|---|---|
| ≥30 | 1 | 1.5-3g q6h-q8h |
| 15-29 | 5 | 1.5-3g q12h |
| 5-14 | 9 | 1.5-3g q24h |
| [1] |
Pediatric Dosing Guidelines
- Children ≥1 year: 300 mg/kg/day IV in equally divided doses every 6 hours (corresponds to 200 mg ampicillin/100 mg sulbactam per kg per day) 1
- Children ≥40 kg: Use adult dosing recommendations 1
- Specific indications:
Special Considerations
Administration Pearls
- For optimal efficacy against organisms with higher MICs, consider extended infusion (4 hours) 3
- Hemodialysis removes approximately 35% of ampicillin and 45% of sulbactam during a 4-hour session; dose after dialysis on dialysis days 5
Clinical Decision Points
- For mild-moderate infections: Standard 1.5g dose (1g ampicillin/0.5g sulbactam) q6h is typically sufficient 1, 6
- For severe infections: Higher dose of 3g (2g ampicillin/1g sulbactam) q6h is recommended 1
- For specific pathogens:
Common Pitfalls
- Underdosing in severe infections or when targeting resistant organisms
- Failure to adjust dosing in renal impairment
- Not considering extended infusion times for difficult-to-treat infections
- Not redosing during prolonged surgical procedures (recommended every 4 hours rather than every 2 hours) 7
Evidence Quality Assessment
The dosing recommendations are primarily based on FDA labeling 1 and clinical guidelines from the American Heart Association 2 and Intensive Care Medicine 2. These recommendations have strong consensus support (Class IIa/B or IIb/C) but are based on limited randomized controlled trials specifically examining dose optimization.
Recent pharmacokinetic studies suggest that extended infusion times (4 hours) may improve target attainment, particularly for pathogens with higher MICs 3, 7.