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Antibiotic (Aminoglycoside) Pregnancy: D — ototoxicity risk to foetus

Gentamicin

Brand names: Cidomycin, Genticin

Adult dose

Dose: 5–7mg/kg IV once daily (Hartford nomogram) or 1mg/kg TDS (traditional)
Route: IV
Frequency: Once daily (preferred) or three times daily
OD dosing preferred for most infections. Infuse over 30min. Therapeutic drug monitoring mandatory. Surgical prophylaxis: 1.5mg/kg single dose IV.

Paediatric dose

Dose: 2.5 mg/kg
Route: IV
Frequency: Every 8 hours
Max: 80mg per dose
Neonates: 4–5mg/kg OD (check local protocol). Children: 2.5mg/kg TDS or 7mg/kg OD.
Paediatric weight-based calculator

Neonates: 4–5mg/kg OD (check local protocol). Children: 2.5mg/kg TDS or 7mg/kg OD.

Clinical pearls

  • Therapeutic monitoring is MANDATORY — measure trough (TDS) or predose level (OD) — local pharmacokinetics team
  • OD gentamicin: check level 6–14h post-dose, plot on Hartford nomogram
  • AVOID in elderly, CKD, pre-existing hearing loss unless no alternative
  • Cumulative ototoxicity: total lifetime dose increases risk — minimise course length
  • Gentamicin + amoxicillin: gold standard for endocarditis prophylaxis in high-risk patients

Contraindications

  • Myasthenia gravis
  • Previous aminoglycoside toxicity
  • Avoid if possible with other nephrotoxic agents

Side effects

  • Nephrotoxicity (dose-dependent, cumulative)
  • Ototoxicity — vestibular (dizziness, ataxia) and cochlear (permanent hearing loss)
  • Neuromuscular blockade

Interactions

  • Furosemide — additive ototoxicity
  • Vancomycin — additive nephrotoxicity
  • NSAIDs — increased nephrotoxicity risk
  • Neuromuscular blocking agents — potentiated

Monitoring

  • Serum gentamicin levels (peak and trough or 6-14h OD)
  • Renal function (before each dose initially)
  • Hearing assessment (prolonged courses)
  • Urine output

Reference: BNFc; BSAC Aminoglycoside Guidelines; Hartford OD Nomogram. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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