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Carbapenem antibiotic Pregnancy: Use only if clearly indicated. Limited data but may be used for serious infections.

Meropenem

Brand names: Meronem

Adult dose

Dose: 500 mg–2 g every 8 hours IV
Route: IV (bolus over 5 min or infusion over 15–30 min)
Frequency: Every 8 hours (or every 6 hours for CNS infections)
Max: 6 g/day (standard); 8 g/day (CNS/extended infusion)
Moderate infections: 500 mg every 8 hours. Severe/ICU: 1 g every 8 hours. CNS infections (meningitis): 2 g every 8 hours. Extended infusion (3 hours) for MDR organisms in critical care. Duration guided by clinical response and microbiological results.

Paediatric dose

Dose: 20 mg/kg
Route: IV
Frequency: Every 8 hours
Max: 2 g/dose
Concentration: 50 mg/ml
3 months–11 years: 10–20 mg/kg every 8 hours. Meningitis: 40 mg/kg every 8 hours (max 2 g). ≥12 years: adult dose. Neonates <7 days: 20 mg/kg every 12 hours.

Dose adjustments

Renal

eGFR 25–50: 1 g every 12h; eGFR 10–25: 500 mg every 12h; eGFR <10: 500 mg every 24h.

Hepatic

No dose adjustment required.

Paediatric weight-based calculator

3 months–11 years: 10–20 mg/kg every 8 hours. Meningitis: 40 mg/kg every 8 hours (max 2 g). ≥12 years: adult dose. Neonates <7 days: 20 mg/kg every 12 hours.

Clinical pearls

  • Critically avoid combination with valproate — meropenem can halve valproate levels within 24 hours
  • Broadest spectrum beta-lactam for Gram-negative organisms including Pseudomonas and ESBL producers
  • Reserve for ESBL-producing Enterobacteriaceae, Pseudomonas, and polymicrobial severe infections
  • Carbapenem stewardship essential — preserve for resistant organisms
  • Less seizure-prone than imipenem-cilastatin

Contraindications

  • Hypersensitivity to carbapenems
  • Caution in penicillin allergy (1–5% cross-reactivity)

Side effects

  • Diarrhoea
  • Nausea and vomiting
  • Elevated liver enzymes
  • Thrombocytopenia
  • Seizures (lower seizure threshold than imipenem)
  • Hypersensitivity reactions
  • C. difficile colitis

Interactions

  • Sodium valproate — significantly reduces valproate levels (avoid combination)
  • Probenecid — increases meropenem levels (avoid)

Monitoring

  • U&E
  • LFTs
  • Microbiological response
  • Valproate levels if on valproate
  • Seizure risk

Reference: BNFc; BNF; PHE Antimicrobial Stewardship Guidelines; NICE NG51. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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