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Carbapenem — Severe / MDR Gram-Negative Infections / Febrile Neutropenia Pregnancy: Use with caution — limited data; animal studies show no teratogenicity; use for serious infections when benefit outweighs risk

Meropenem (Paediatric)

Brand names: Meronem

Adult dose

Dose: Severe infections: 1–2 g IV every 8 hours; meningitis: 2 g IV every 8 hours
Route: IV bolus or infusion
Frequency: Every 8 hours
Max: 6 g/day
Adult reference — see paediatric dose section

Paediatric dose

Dose: 10–20 mg/kg every 8 hours (standard); Meningitis/cystic fibrosis/febrile neutropenia: 40 mg/kg every 8 hours mg/kg
Route: IV bolus (over 5 minutes) or infusion (over 15–30 minutes)
Frequency: Every 8 hours
Max: 2 g per dose (standard); 40 mg/kg per dose (severe — max 2 g)
BNFc: neonates — 20 mg/kg every 12 hours (term); extended-infusion meropenem (4-hour infusion) used in MDR organisms (maximises time above MIC). Unlike ertapenem, meropenem covers Pseudomonas aeruginosa — critical for empirical febrile neutropenia regimens. Caution in patients on valproate — carbapenems reduce valproate levels by 50–70%.

Dose adjustments

Renal

CrCl 25–50: every 12 hours; CrCl 10–25: 50% dose every 12 hours; CrCl <10: 50% dose every 24 hours

Hepatic

No dose adjustment required

Paediatric weight-based calculator

BNFc: neonates — 20 mg/kg every 12 hours (term); extended-infusion meropenem (4-hour infusion) used in MDR organisms (maximises time above MIC). Unlike ertapenem, meropenem covers Pseudomonas aeruginosa — critical for empirical febrile neutropenia regimens. Caution in patients on valproate — carbapenems reduce valproate levels by 50–70%.

Clinical pearls

  • Valproate interaction is the most dangerous — seizure breakthrough has been reported in epileptic children on valproate when meropenem started; check all antiepileptic medications before prescribing; if meropenem essential, increase valproate dose and monitor levels
  • Extended-infusion meropenem: 4-hour infusion of standard dose optimises time above MIC for resistant organisms (Pseudomonas MIC 4–8 mg/L) — used in specialist units for MDR organisms; requires stability data (meropenem stable 4–8 hours at room temperature)
  • De-escalation: always aim to de-escalate from meropenem once sensitivities known — antimicrobial stewardship principle; carbapenem overuse drives resistance
  • Seizures: meropenem (imipenem more so) can lower seizure threshold — use with caution in children with epilepsy; meropenem preferred over imipenem-cilastatin in neuro patients

Contraindications

  • Beta-lactam anaphylaxis
  • Concurrent valproate (significant interaction — see clinical pearls)

Side effects

  • Diarrhoea (C. difficile risk — broad spectrum)
  • Nausea
  • Elevated LFTs
  • Headache
  • Rash
  • Seizures (rare — less than imipenem)
  • Thrombocytopaenia/thrombocytosis

Interactions

  • Valproic acid — CRITICAL: all carbapenems reduce valproate levels by 50–70%; mechanism unclear; may cause seizure breakthrough — monitor valproate levels and consider alternative antibiotic or increase valproate dose
  • Probenecid — increases meropenem levels

Monitoring

  • Renal function (dose adjustment)
  • Valproate levels (CRITICAL if co-prescribed)
  • LFTs and FBC
  • C. difficile if diarrhoea
  • Clinical response and culture sensitivities

Reference: BNF for Children; PHE Antibiotic Guidelines; ECIL Febrile Neutropenia Guidelines; NICE Sepsis 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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