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Combination of
Ampicillin Penicillin antibiotic
Sulbactam Beta-lactamase inhibitor
Clinical data
MedlinePlus a693021
Legal status
ATC code J01CR01
PubChem CID 656676
ChemSpider 10482157 YesY
 YesY (what is this?)  (verify)

Ampicillin/sulbactam is a combination of the common penicillin-derived antibiotic ampicillin and sulbactam, an inhibitor of bacterial beta-lactamase. Two different forms of the drug exist. The first, developed in 1987 and marketed in the United States under the tradename Unasyn, generic only outside of the United States, is an intravenous antibiotic. The second, an oral form called sultamicillin, is marketed under the trade name Ampictam outside of the United States. And generic only in the United States, ampicillin/sulbactam is used to treat infections caused by bacteria resistant to beta-lactam antibiotics. Sulbactam blocks the enzyme which breaks down ampicillin and thereby allows ampicillin to attack and kill the bacteria.

Ampicillin-2D-skeletal.png Sulbactam.svg Sultamicillin schematic.svg
Skeletal formula of ampicillin Skeletal formula of sulbactam Skeletal formula of sultamicillin, highlighting ampicillin in blue and sulbactam in orange

Ampicillin/sulbactam is also used when the cause of an infection is not known (empiric therapy), such as intra-abdominal infections, skin infections, pneumonia, and gynecologic infections. It is active against a wide range of bacterial groups, including Staphylococcus aureus, Enterobacteriaceae, and anaerobic bacteria. Importantly, it is not active against Pseudomonas aeruginosa and should not be used alone when infection with this organism is suspected or known.

Adverse drug effects[edit]


  • Unasyn (USA)
  • Subacillin (Taiwan)
  • Sultamicillin