Antibiotic (Carbapenem) Pregnancy: B — limited data but generally considered safe

Meropenem

Brand names: Meronem

Adult dose

Dose: 500mg–2g three times daily IV

Route: IV

Frequency: Three times daily

Mild-moderate infections: 500mg TDS. Severe (nosocomial, Pseudomonas): 1–2g TDS. Meningitis: 2g TDS. Infuse over 15–30 min (standard) or 3–4h extended infusion for MDR organisms.

Paediatric dose

Dose: 20 mg/kg

Route: IV

Frequency: Three times daily

Max: 2000mg per dose

Meningitis/severe: 40mg/kg TDS. Neonates: 20mg/kg BD.

Paediatric weight-based calculator

Patient weight (kg)

Meningitis/severe: 40mg/kg TDS. Neonates: 20mg/kg BD.

Clinical pearls

CAUTION with valproate — meropenem reduces valproate levels by 60–70% in 24h — risk of breakthrough seizures
Reserve for resistant organisms, ESBL, nosocomial infections — antimicrobial stewardship
Cross-reactivity with penicillin allergy: very low (~1%) — can often be used if beta-lactam allergy is mild/non-anaphylaxis
Extended infusion (3–4h) maintains time above MIC — preferred for resistant organisms
Reduces dose in renal impairment: eGFR 10–25 → 500mg BD; eGFR <10 → 500mg OD

Contraindications

Carbapenem/beta-lactam allergy

Side effects

GI disturbance
Rash
Seizures (high doses, renal impairment)
Clostridium difficile
Elevated LFTs

Interactions

Valproate — significantly reduces valproate levels (can cause seizures — avoid combination)
Probenecid — increases meropenem levels

Monitoring

Renal function
Neurological status (seizure risk)
Valproate levels if co-prescribed

Reference: BNFc; BNF; PHE Carbapenem Guidance; MERINO trial. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways