What is Unasyn (Ampicillin-Sulbactam)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: March 27, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

Unasyn, also known as Ampicillin-Sulbactam, is a combination antibiotic used to treat various bacterial infections, including intra-abdominal infections, by inhibiting the growth of bacteria.

Overview of Unasyn

Unasyn is a combination of ampicillin, a beta-lactam antibiotic, and sulbactam, a beta-lactamase inhibitor, which works by extending the spectrum of ampicillin to include beta-lactamase-producing bacteria 1.

Mechanism of Action

The mechanism of action of Unasyn involves the inhibition of bacterial cell wall synthesis, ultimately leading to the death of the bacteria.

Clinical Use

Unasyn is used to treat a variety of infections, including intra-abdominal infections, skin and skin structure infections, and respiratory tract infections.

  • In the context of intra-abdominal infections, Unasyn may be used as an empiric therapy, especially in cases where the infection is suspected to be caused by bacteria that are susceptible to ampicillin and sulbactam.
  • However, the use of Unasyn should be guided by local resistance patterns and the severity of the infection.
  • In cases where the infection is caused by resistant bacteria, such as ESBL-producing Enterobacteriaceae, other antibiotics may be more effective.

Important Considerations

When using Unasyn, it is essential to consider the potential for allergic reactions, particularly in patients with a history of penicillin allergy.

  • Additionally, Unasyn may interact with other medications, such as warfarin, and may affect the gut flora, leading to changes in the absorption of other medications.
  • The use of Unasyn should be monitored closely, and the patient should be educated on the potential side effects and the importance of completing the full course of therapy.

Resistance Patterns

The increasing prevalence of antibiotic-resistant bacteria, including ESBL-producing Enterobacteriaceae, has limited the use of Unasyn in some cases 1.

  • However, Unasyn may still be effective against some strains of bacteria, and its use should be guided by local resistance patterns and the severity of the infection.
  • The development of new antibiotics, such as ceftolozane/tazobactam and ceftazidime/avibactam, has provided alternative treatment options for infections caused by resistant bacteria.

From the Research

Definition and Use of Unasyn

  • Unasyn is a combination drug used for the treatment of infections as well as a prophylactic intervention prior to surgical or endoscopic interventions 2.
  • It is a broad spectrum antibiotic of the penicillin family that inhibits beta-lactamases, ensuring activity of the ampicillin against resistant organisms 2.

Pharmacokinetics

  • Peak serum levels of Unasyn are reached in 15 min to 1 hr after an IV infusion of 15 min 2.

Relevance to Other Studies

  • The other studies provided do not directly relate to the definition or use of Unasyn, but rather discuss topics such as evidence-based practice 3, communication barriers in healthcare 4, one to one specialling in acute care hospitals 5, and advanced practice nursing roles 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Unasyn (ampicillin sodium/sulbactam sodium).

Gastroenterology nursing : the official journal of the Society of Gastroenterology Nurses and Associates, 1993

Research

One to one specialling and sitters in acute care hospitals: A scoping review.

International journal of nursing studies, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.