[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Carbapenems](https://durgical.com/en/pharmacology/classes/carbapenems/) › Ertapenem

[Pharmacology](https://durgical.com/en/pharmacology/) · [Carbapenems](https://durgical.com/en/pharmacology/classes/carbapenems/)

# Ertapenem

A once-daily carbapenem for community infections and ESBL producers; unlike meropenem it does not cover Pseudomonas or Acinetobacter.

Updated 2026-11-01

- Class: [Carbapenems](https://durgical.com/en/pharmacology/classes/carbapenems/)
- Enzyme: Penicillin-binding proteins (bacterial transpeptidases)
- ATC code: J01DH03

✂**Penicillin-binding proteins (bacterial transpeptidases)**Ertapenem

ⓘ No structure of ertapenem bound to a penicillin-binding protein is available; the figure shows meropenem, a carbapenem that acylates the same site of PBP3 (Pseudomonas aeruginosa).

**Target in 3D:** Penicillin-binding proteins (bacterial transpeptidases). PDB structure 3PBR (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/3PBR) · Drag to rotate · pinch to zoom

## Mechanism of action

Ertapenem binds penicillin-binding proteins (in Escherichia coli preferentially PBP2 and PBP3) and stops cell-wall synthesis. It is stable to penicillinases, cephalosporinases and ESBL, but metallo-β-lactamases hydrolyse it. High binding to albumin gives it a long half-life.

- Binds PBP2 and PBP3 of gram-negative bacteria
- Resists ESBL; metallo-β-lactamases destroy it
- Wall cross-linking stops and the cell lyses

## Pharmacokinetics

**Absorption**
Intravenous, or intramuscular when reconstituted with lidocaine.

**Distribution**
Highly bound to albumin; the bound fraction falls as levels rise.

**Metabolism**
The main metabolite is an inactive form with the β-lactam ring opened.

**Elimination**
Mainly by the kidney.

**Half-life**
About 4 hours in healthy young adults, which allows one dose a day.

## Indications

- Complicated intra-abdominal infections. [Peritonitis →](https://durgical.com/en/conditions/peritonitis/)
- Complicated skin infections, including diabetic foot infection without osteomyelitis. [Diabetic foot →](https://durgical.com/en/conditions/diabetic-foot/)
- Community-acquired pneumonia. [Community-acquired pneumonia →](https://durgical.com/en/conditions/community-acquired-pneumonia/)
- Complicated urinary tract infections, including pyelonephritis (useful for ESBL producers). [Acute pyelonephritis →](https://durgical.com/en/conditions/acute-pyelonephritis/)
- Acute pelvic infections, including postpartum endomyometritis. [Puerperal infection (postpartum endometritis and maternal sepsis) →](https://durgical.com/en/conditions/puerperal-infection/)
- Prevention of surgical site infection after elective colorectal surgery. [Surgical site infection →](https://durgical.com/en/conditions/surgical-site-infection/)

## Adverse effects

### Common

- Diarrhoea, nausea, headache
- Infusion-site reactions and phlebitis
- Rash

### Serious (rare, important)

- Anaphylaxis
- Seizures and other CNS effects
- Clostridioides difficile diarrhoea

## Contraindications

- Hypersensitivity to ertapenem or other carbapenems; anaphylaxis to any β-lactam
- Intramuscular use (lidocaine diluent) in allergy to amide local anaesthetics

## Key interactions

**Valproic acid / divalproex**
Valproate levels fall; risk of breakthrough seizures; generally avoided.

**Probenecid**
Reduces renal clearance of ertapenem; not recommended.

## What is monitored

- Kidney function
- Neurological status, especially with kidney failure
- Clinical response; culture results to confirm the organism is covered

## Administration and safety

- IV infusion after reconstitution and dilution in saline, or deep IM injection when reconstituted with lidocaine; the two preparations are not interchangeable.
- Not mixed or infused with other drugs in the same line; not diluted in dextrose solutions.
- Once-daily schedule eases outpatient treatment.

## Nursing care

- Ask about β-lactam and local anaesthetic allergies and about valproic acid.
- Monitor for confusion or seizures in older adults and kidney failure.
- Teaching for outpatient therapy: keep the daily schedule, report rash, diarrhoea or fever.

## Pregnancy and breastfeeding

Data from a small number of cases are insufficient to define a risk; animal studies showed no malformations. It is used when clearly needed.

## Memory aid

ERTApenem = «ERTA once a day, but no PEA»: no Pseudomonas, no Enterococcus, no Acinetobacter.

## Test yourself

Think of the answer, then tap the question to see it.

## Why can ertapenem be given once a day while meropenem cannot?

Its high binding to albumin gives it a half-life of about 4 hours, versus about 1 hour for meropenem.

## A patient with hospital-acquired pneumonia by Pseudomonas is started on ertapenem. What is wrong?

Ertapenem has no useful activity against Pseudomonas aeruginosa; meropenem or imipenem would be needed.

## Why is intramuscular ertapenem contraindicated in some patients with drug allergies?

The IM preparation is reconstituted with lidocaine, so allergy to amide local anaesthetics rules it out.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/ertapenem/)

## Related drugs

- [Meropenem](https://durgical.com/en/pharmacology/meropenem/)
- [Imipenem–cilastatin](https://durgical.com/en/pharmacology/imipenem-cilastatin/)
- [Valproic acid](https://durgical.com/en/pharmacology/valproic-acid/)

## Related conditions

- [Peritonitis](https://durgical.com/en/conditions/peritonitis/)
- [Diabetic foot](https://durgical.com/en/conditions/diabetic-foot/)
- [Community-acquired pneumonia](https://durgical.com/en/conditions/community-acquired-pneumonia/)
- [Acute pyelonephritis](https://durgical.com/en/conditions/acute-pyelonephritis/)
- [Puerperal infection (postpartum endometritis and maternal sepsis)](https://durgical.com/en/conditions/puerperal-infection/)
- [Surgical site infection](https://durgical.com/en/conditions/surgical-site-infection/)

[← Back to the class: Carbapenems](https://durgical.com/en/pharmacology/classes/carbapenems/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - ERTAPENEM- ertapenem sodium injection](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5b050245-aa03-4e28-e063-6394a90aeabc) (DailyMed (U.S. National Library of Medicine), 2026); [Ertapenem Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a614001.html) (MedlinePlus (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 58 (McGraw Hill, 2023); [RCSB PDB - 3PBR: Crystal structure of PBP3 complexed with meropenem](https://www.rcsb.org/structure/3PBR) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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