Ertapenem – A Quick Reference Guide
| Feature |
What you need to know |
| Drug class |
Carbapenem β‑lactam antibiotic |
| Common brand names |
Invanz®, Ertapenem (generic) |
| Route of administration |
Intravenous (IV) or subcutaneous (SC) only – no oral formulation |
| Typical adult dose |
1 g IV or SC once daily (adjust for kidney function) |
| Spectrum of activity |
Broad‑spectrum Gram‑positive & Gram‑negative bacteria except Pseudomonas aeruginosa and most Enterobacteriaceae that produce carbapenemases (e.g., KPC, NDM). Covers anaerobes (Bacteroides, Clostridia) and many Enterococci. |
| Main indications |
• Complicated intra‑abdominal infections (cIAIs) < 72 h after surgery < 48 h after admission (peri‑operative prophylaxis)
• Complicated urinary tract infections (cUTIs)
• Complicated skin and soft‑tissue infections (cSSIs)
• Bacteremia/sepsis of unknown origin (short‑term therapy) |
| Not typically used for |
Community‑acquired pneumonia, viral infections, MRSA (unless combined with other drugs) |
How It Works
Ertapenem binds to multiple penicillin‑binding proteins (PBPs) on the bacterial cell wall, inhibiting cell‑wall synthesis and causing cell lysis. It’s a “β‑lactamase‑resistant” drug – most β‑lactamases, including those from many Enterobacteriaceae, cannot hydrolyze it.
Pharmacokinetics (Adults)
| Parameter |
Typical values |
| Absorption |
— (parenteral only) |
| Distribution |
1.1–1.4 L/kg; moderate protein binding (≈ 15 %) |
| Metabolism |
Minimal – largely unchanged |
| Excretion |
Renal (≈ 70 % unchanged in urine); dose adjustment needed for CKD |
| Half‑life |
2–3 h (short, but once‑daily dosing is adequate due to high protein binding and broad spectrum) |
Dose Adjustment by Renal Function
| CrCl (mL/min) |
Dose (IV/SC) |
| ≥ 50 |
1 g once daily |
| 30–49 |
500 mg once daily |
| 10–29 |
250 mg once daily |
| < 10 |
Not recommended (consider alternative agents) |
(Use actual serum creatinine and estimate CrCl with Cockcroft–Gault or MDRD; adjust accordingly.)
Common Side Effects
| Symptom |
Frequency |
What to watch for |
| Diarrhea (often mild) |
~10 % |
Severe watery diarrhea may signal Clostridioides difficile infection; report promptly |
| Rash or itching |
< 5 % |
Severe rash or anaphylaxis rare but possible |
| Nausea/vomiting |
< 5 % |
Usually mild; anti‑emetics can help |
| Hypersensitivity reactions (anaphylaxis, angioedema) |
Rare |
Immediate medical attention required |
| Elevated liver enzymes (rare) |
< 5 % |
Monitor LFTs in long‑term or high‑dose therapy |
Contraindications & Precautions
| Situation |
Recommendation |
| Known hypersensitivity to carbapenems, penicillins, or β‑lactam antibiotics |
Contraindicated |
| Severe renal impairment (CrCl < 10 mL/min) |
Avoid; not studied in this population |
| Pregnancy |
Category B (no evidence of risk in humans). Use only if benefits outweigh potential risks. |
| Lactation |
Limited data; consider the safety profile of the infant before use. |
| Children < 2 years |
Not approved; limited safety data |
| Recent exposure to carbapenem‑resistant organisms |
Use with caution; consider alternative agents if resistance likely |
| Concomitant use of other nephrotoxic agents |
Monitor renal function |
Drug Interactions
Ertapenem has few clinically significant interactions, largely because it’s not metabolized by CYP enzymes or affected by many transporters. Still:
- Valproic acid – may reduce serum levels; monitor therapeutic drug levels if used concomitantly.
- Other antimicrobials – no dose adjustment needed, but careful monitoring for additive toxicity (e.g., nephrotoxicity with aminoglycosides).
- Probenecid – may decrease renal excretion; monitor CrCl and consider dose adjustment.
Practical Tips for Clinicians
- Use in “difficult” infections: Ertapenem is often chosen for single‑dose convenience and its anaerobic coverage. It’s a good choice when the pathogen is likely Bacteroides fragilis, Escherichia coli, Klebsiella pneumoniae, Enterococcus spp. (except VRE), and Streptococcus spp.
- Avoid overuse: Overprescribing carbapenems can promote resistance. Reserve ertapenem for documented or strongly suspected gram‑negative/anaerobic infections.
- Check local antibiogram: Some hospitals report carbapenem‑resistant Enterobacterales (CRE). If CRE is likely, ertapenem will not be effective.
- Combination therapy: For polymicrobial infections involving Pseudomonas or Acinetobacter spp., use ertapenem with a second agent (e.g., piperacillin‑tazobactam or cefepime).
- Monitor for C. difficile: Even though it’s a single‑daily dose, prolonged therapy increases the risk. Watch for watery diarrhea and consider stool testing if symptoms arise.
Bottom Line
Ertapenem is a reliable, once‑daily carbapenem for many intra‑abdominal, urinary, and soft‑tissue infections. Its key strengths are broad anaerobic coverage and a convenient dosing schedule. However, it should be used judiciously, with renal dose adjustments and careful monitoring for hypersensitivity or C. difficile infection.
When in doubt, always check your local resistance patterns and consider infectious disease consultation for complex cases.