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Amphenicol — Meningitis (Alternative) / Topical Eye Infections Pregnancy: Avoid near term — risk of grey baby syndrome in neonate; use alternatives

Chloramphenicol

Brand names: Kemicetine (systemic), Chloramphenicol eye drops/ointment

Adult dose

Dose: Systemic (meningitis alternative in penicillin allergy): 12.5–25 mg/kg IV every 6 hours; Eye drops: 0.5% 1 drop every 2 hours reducing to 4 times daily; Eye ointment: 1% applied 3–4 times daily
Route: IV (systemic) or topical (ophthalmic)
Frequency: Every 6 hours (systemic); multiple daily (ophthalmic)
Max: 100 mg/kg/day systemic (max 4 g/day)
Systemic use now limited in UK due to aplastic anaemia risk — reserved for bacterial meningitis in penicillin/cephalosporin allergy. Excellent CNS penetration. Topical eye use remains widespread and safe. WHO essential medicine for resource-limited settings.

Paediatric dose

Dose: 12.5–25 mg/kg mg/kg
Route: IV or oral
Frequency: Every 6 hours
Max: 100 mg/kg/day
BNFc: CRITICAL — grey baby syndrome in neonates (<1 month) if dose not adjusted; neonates require much lower doses; always calculate carefully and use neonatal formulary

Dose adjustments

Renal

Reduce dose in severe renal impairment — active metabolite accumulates

Hepatic

Reduce dose in hepatic impairment — hepatically conjugated; monitor levels

Paediatric weight-based calculator

BNFc: CRITICAL — grey baby syndrome in neonates (<1 month) if dose not adjusted; neonates require much lower doses; always calculate carefully and use neonatal formulary

Clinical pearls

  • Grey baby syndrome: neonates lack UDP-glucuronyl transferase — cannot conjugate chloramphenicol; toxic accumulation → cardiovascular collapse; ALWAYS use neonatal-appropriate doses (12.5–25 mg/kg/day in neonates vs 50–100 mg/kg/day in older children)
  • Aplastic anaemia is idiosyncratic (not dose-dependent) and can occur even after topical eye use (via nasolacrimal duct absorption) — extremely rare but irreversible; monitor FBC if systemic courses
  • CNS penetration excellent (>50% of plasma levels in CSF) — one of the best for bacterial meningitis when beta-lactams contraindicated
  • Eye drops: OTC available in UK for bacterial conjunctivitis — safe topically; advise patients to report systemic symptoms (very rare aplastic anaemia risk)

Contraindications

  • Bone marrow suppression
  • Prophylactic use (risk outweighs benefit)
  • Pregnancy (risk of grey baby syndrome in neonate)
  • Neonatal period at standard doses (grey baby syndrome)

Side effects

  • Aplastic anaemia (irreversible — idiosyncratic, ~1 in 25,000–40,000 courses; risk even with topical use — very rare)
  • Reversible dose-dependent bone marrow suppression
  • Grey baby syndrome (neonates — cardiovascular collapse, grey pallor, hypothermia, vomiting, cyanosis)
  • GI disturbance
  • Optic neuritis (prolonged use)
  • Peripheral neuropathy

Interactions

  • Warfarin — significantly enhanced INR (CYP2C9 inhibition)
  • Phenytoin — increased phenytoin toxicity
  • Methotrexate — increased toxicity
  • Paracetamol — increased chloramphenicol levels
  • Rifampicin — reduces chloramphenicol levels

Monitoring

  • FBC every 3 days during systemic courses (mandatory)
  • Serum levels in neonates (target peak 15–25 mg/L, trough <15 mg/L)
  • LFTs
  • Neurological assessment (peripheral neuropathy)

Reference: BNFc; BNF 90; PHE Meningitis Antibiotic Guidelines; NICE NG 41 Meningitis; WHO Essential Medicines List 2023. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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