Carbapenem — ESBL / Complicated Intra-Abdominal / Community OPAT Pregnancy: Use with caution — animal studies show no teratogenicity; limited human data

Ertapenem

Brand names: Invanz

Adult dose

Dose: 1 g IV once daily

Route: Intravenous infusion over 30 minutes

Frequency: Once daily

Max: 1 g/day

Unique once-daily carbapenem — ideal for OPAT (outpatient parenteral antibiotic therapy). Spectrum: ESBL-producing enterobacteriaceae, complicated UTI, intra-abdominal, skin and soft tissue, community-acquired pneumonia. IMPORTANT: NO Pseudomonas or Acinetobacter activity — use meropenem/piperacillin-tazobactam if Pseudomonas suspected.

Paediatric dose

Dose: 15 mg/kg mg/kg

Route: IV

Frequency: Twice daily (≤12 years)

Max: 1 g/day

BNFc: licensed ≥3 months; 15 mg/kg BD in children ≤12 years (max 1 g/day)

Dose adjustments

Renal

CrCl <30 mL/min: reduce to 500 mg once daily; haemodialysis: 500 mg once daily (give after dialysis on dialysis days)

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Patient weight (kg)

BNFc: licensed ≥3 months; 15 mg/kg BD in children ≤12 years (max 1 g/day)

Clinical pearls

Critical interaction: carbapenems (all, including ertapenem) reduce valproate plasma levels by up to 70% — mechanism unclear (increased renal clearance); if patient is on valproate for epilepsy, consider alternative antibiotic or increase valproate dose and monitor levels closely
Ertapenem does NOT cover Pseudomonas or Acinetobacter — this is its key limitation vs meropenem; check this before prescribing empirically
OPAT advantage: once-daily dosing allows outpatient IV treatment of ESBL infections — reduces hospital admission
ESBL-producing E. coli pyelonephritis: ertapenem is first-line when ESBL confirmed (MERINO trial: meropenem/ertapenem superior to pip-taz for ESBL bacteraemia)

Contraindications

Carbapenem hypersensitivity
Beta-lactam anaphylaxis (cross-reactivity)

Side effects

Diarrhoea (most common)
Nausea
Headache
Phlebitis
Elevated LFTs
Seizures (rare — less than imipenem)
C. difficile
Thrombocytopaenia

Interactions

Valproic acid — carbapenems significantly reduce valproate levels (50–70% reduction) — monitor and consider alternative antibiotic or increase valproate dose
Probenecid — increases ertapenem levels

Monitoring

Renal function (dose adjustment)
Valproate levels (if co-prescribed)
LFTs
C. difficile if diarrhoea
Seizure history

Reference: BNFc; BNF 90; MERINO Trial 2018; PHE ESBL Management Guidelines; NICE OPAT Guidance. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways