ertapenem
Brand: Invanz
Prototype: imipenem-cilastatin
Drug Class: carbapenem antibiotic
Drug Family: antibiotic
Subclass: once-daily carbapenem (no Pseudomonas activity)
Organ Systems: infectious-disease
Mechanism of Action
Inhibits bacterial cell wall synthesis by binding PBPs; unlike imipenem and meropenem, ertapenem has a long half-life allowing once-daily dosing but lacks activity against Pseudomonas aeruginosa and Acinetobacter.
penicillin-binding proteins (PBPs)
Indications
- complicated intra-abdominal infections
- complicated UTI including pyelonephritis
- community-acquired pneumonia
- complicated skin/soft tissue infections
- acute pelvic infections
- surgical prophylaxis (colorectal)
Contraindications
- carbapenem/beta-lactam hypersensitivity
- lidocaine allergy (IM formulation)
Adverse Effects
Common
- diarrhea
- nausea
- headache
- vaginitis
Serious
- C. difficile colitis
- anaphylaxis
- seizures (less frequent than imipenem)
- encephalopathy
Pharmacokinetics (ADME)
| Absorption | IV or IM; IM bioavailability ~92% |
| Distribution | highly protein-bound; widely distributed; limited CSF penetration |
| Metabolism | hydrolysis of beta-lactam ring to inactive metabolite |
| Excretion | renal (80% — 38% as active drug, remainder as inactive metabolite) |
| Half-life | 4 hours |
| Onset | rapid |
| Peak | end of IV infusion; 2 hours IM |
| Duration | 24 hours (once-daily dosing) |
| Protein Binding | 85–95% |
| Vd | low-moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| valproate | reduces valproate levels; may cause loss of seizure control; avoid | major |
| probenecid | reduces renal excretion of ertapenem | minor |
Nursing Considerations
- Avoid the valproate combination; monitor valproate levels if concurrent use cannot be avoided.
- IM formulation uses 1% lidocaine as diluent; verify patient has no lidocaine allergy before IM administration.
- IV infusion: administer over 30 minutes; IM injections given into large muscle.
- Reduce dose when CrCl is <30 mL/min; ertapenem is removed by hemodialysis — supplement dose after dialysis.
Clinical Pearls
- Ertapenem's once-daily dosing makes it the preferred carbapenem for outpatient parenteral antibiotic therapy (OPAT) for ESBL-producing organisms.
- Critically, ertapenem has NO activity against Pseudomonas aeruginosa or Acinetobacter; meropenem or imipenem must be used for these pathogens.
Safety Profile
Pregnancy generally-safe
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.