Aminoglycoside Ototoxicity — RACP Adult Medicine MCQ

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EasyClinical PharmacologyAminoglycoside OtotoxicityRACP Adult Medicine

A 70-year-old man on regular gentamicin for prosthetic valve endocarditis develops tinnitus and unsteadiness. His gentamicin trough level is 2.5 mg/L (target <1 mg/L). What type of toxicity is this?

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Correct answer: B — Vestibulotoxicity and cochleotoxicity

Aminoglycoside (gentamicin) ototoxicity manifests as both vestibulotoxicity (unsteadiness, vertigo) and cochleotoxicity (tinnitus, hearing loss). It is related to cumulative dose and elevated trough levels (>1 mg/L). Damage to cochlear hair cells is usually irreversible. Monitoring trough levels, maintaining adequate hydration, and limiting treatment duration are key preventive strategies. Once-daily dosing reduces toxicity compared to multiple daily dosing (for non-endocarditis indications).

Reference: AMH – 2025 – Aminoglycosides; eTG – 2025 – Antibiotic Guidelines