gentamicin

gentamicin is evaluated for the following indications with varying evidence strength: Gram-positive infective endocarditis (evidence tier A), Gram-negative sepsis (evidence tier B), Complicated urinary tract infection (evidence tier B). See the full indication matrix with dosing and citations above on this page.

Common side effects of gentamicin (≥ 1 in 100): Dose-dependent kidney impairment (creatinine rise, eGFR drop), Vestibular disturbances (vertigo, gait instability), High-frequency hearing loss, Local irritation at the injection site. See the Safety section for uncommon and serious reactions.

FDA category D. FDA category D. Adverse fetal effects are documented: sensorineural deafness in newborns has been reported after in utero exposure to aminoglycosides. Gentamicin is used only in life-threatening infections when no alternatives exist and benefit to the mother outweighs fetal risk. The decision is made jointly with the obstetrician-gynecologist and infectious disease specialist.

Gentamicin passes into breast milk in small amounts and is poorly absorbed from the infant GI tract. LactMed classifies it as compatible with breastfeeding. Monitor the infant for diarrhea and candidiasis.

gentamicin is contraindicated in: Hypersensitivity to aminoglycosides in history; Myasthenia gravis or myasthenic syndrome; Severe renal impairment without ability to monitor drug levels and eGFR; Pregnancy except in life-threatening infections (FDA category D); Concurrent high-dose loop diuretics in patients at ototoxicity risk. Full list in the Safety section.

FDA boxed warning: gentamicin causes nephrotoxicity and oto- and vestibulotoxicity, including irreversible. Risk increases with renal impairment, therapy longer than 10 days, high cumulative doses, concomitant nephrotoxic or ototoxic agents. Neuromuscular blockade up to respiratory failure has been reported with concomitant muscle relaxants and in myasthenic patients. Therapy is conducted with mandatory monitoring of drug levels, renal function, and hearing.

the spectrum is narrow – gentamicin acts on gram-negative rods and some gram-positive cocci in synergy with a beta-lactam. It is ineffective against anaerobes and atypical pathogens.

ototoxicity has been reported with short 5-7-day courses in susceptible patients (m.1555A>G genetic variant, older age, renal impairment).

the therapeutic index is narrow; without level monitoring (or at minimum eGFR and audiogram), the risk of irreversible hearing loss and renal failure rises several-fold.