Ampicillin-Sulbactam Oral Dosing
Ampicillin-sulbactam is not available in an oral formulation in the United States; however, sultamicillin (the oral prodrug) is available in some countries at a dose of 375-750 mg twice daily for adults with normal renal function. 1
Oral Formulation: Sultamicillin
Sultamicillin is a double ester prodrug that is rapidly hydrolyzed to ampicillin and sulbactam after oral administration, providing an oral alternative to intravenous ampicillin-sulbactam. 1
Standard Adult Dosing
- 375-750 mg orally twice daily for community-acquired infections including upper and lower respiratory tract infections, urinary tract infections, and skin/soft tissue infections 1
- The twice-daily dosing provides effective outpatient therapy while maintaining adequate drug levels 1
Clinical Context
- Sultamicillin is particularly appropriate for infections where beta-lactamase-producing organisms are suspected, including Haemophilus influenzae and Branhamella catarrhalis 1
- It provides convenient outpatient follow-up therapy after initial parenteral ampicillin-sulbactam treatment 1
Important Caveat: Geographic Availability
Sultamicillin is not FDA-approved or commercially available in the United States. If you are practicing in the U.S., oral ampicillin-sulbactam therapy is not an option, and alternative oral beta-lactam/beta-lactamase inhibitor combinations (such as amoxicillin-clavulanate) should be considered instead.
Intravenous Dosing Reference (For Context)
Since oral formulations are limited, understanding IV dosing helps contextualize when parenteral therapy is needed:
- Standard IV dosing: 1.5-3 g every 6 hours (ampicillin 1-2 g plus sulbactam 0.5-1 g) 2, 3
- Severe infections: Up to 12 g/day divided into 4 doses (3 g every 6 hours) for conditions like endocarditis 2, 3
- Extended infusions (4 hours) are recommended for high-dose regimens to optimize pharmacokinetic/pharmacodynamic properties 2
Adverse Effects
The primary side effect of sultamicillin is diarrhea/loose stools, which is typically mild to moderate in severity with low discontinuation rates. 1 No significant systemic toxicity has been documented with extensive laboratory monitoring. 1