Selected Antimicrobial Information – Farm Animal

Ampicillin-Sulbactam [Farm Animal]

Restriction Status



Species Usage Dose
Camelids Label dose No labeled dose.
Cattle Label dose No labeled dose.
Small Ruminants Label dose No labeled dose.
Swine Label dose No labeled dose.

Brand Name(s)



Ampicillin sodium-sulbactam sodium is a bactericidal, time-dependent β-lactam antibiotic with improved activity against Gram-negative organisms when compared to penicillin. The addition of sulbactam improves activity against β-lactamase-producing bacteria, such as Staphylococcus spp., though clavulanic acid is a more potent β-lactamase inhibitor. Activity against Gram-positive organisms is comparable to amoxicillin and ampicillin. Ampicillin-sulbactam distributes widely through the plasma, including into peritoneal and interstitial fluid. It does not penetrate abscesses or sites of tissue necrosis well. Excretion is primarily in urine.

Current Uses within OSU-VMC

  • No labeled indications for food animals.

Contraindicated Uses

  • None

Illegal Uses

  • None

Formulations Available within the OSU Pharmacy

  • Ampicillin/Sulbactam 1.5g (Ampicillin 1g/Sulbactam 0.5g)/vial injectable suspension
  • Ampicilin/Sulbactam 3g (Ampicillin 2g/Sulbactam 1g)/vial injectable suspension
  • Unasyn 1.5g/vial injectable suspension
  • Unasyn 3g/vial injectable suspension


  • Frequently used in extra-label fashion, ideal as a perioperative IV antimicrobial as it is broad-spectrum, water-soluble, and bactericidal.


Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

OSU VMC Antimicrobial Use Guidelines Copyright © 2018 by The Ohio State University College of Veterinary Medicine is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.