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Gentamicin (Garamycin, Gentak)
Updated On: July 23, 2026
Rapid (concentration-dependent killing)
30-60 min after infusion
Post-antibiotic effect extends coverage; dosing interval 24 h for single-dose regimens
NMB potentiation - Aminoglycosides inhibit prejunctional acetylcholine release and reduce postjunctional sensitivity; they prolong non-depolarizing NMB and can cause recurarization. Monitor TOF and titrate reversal carefully.
Prophylaxis timing/dosing - Single preoperative dose within 60 minutes of incision; dose on adjusted body weight in obesity (IBW + 0.4 x (TBW - IBW)) to avoid overdosing.
Nephro/ototoxicity - Minimize concurrent nephrotoxins (NSAIDs, contrast, vancomycin, loop diuretics); maintain intravascular volume.
Drug Interactions - Additive with non-depolarizing NMBs, other nephrotoxins, and ototoxins (loop diuretics); calcium may partially reverse aminoglycoside-induced block.
Pediatric Implications - Weight-based (2.5 mg/kg); neonates need extended dosing intervals due to immature renal clearance.
Obstetric Implications - Category D; crosses the placenta with a risk of fetal ototoxicity. Reserve for serious infections when benefit outweighs risk. Minimal transfer into breast milk.
Relative:
Significant renal impairment
Pre-existing hearing/vestibular loss
Caution:
Concurrent nephrotoxins or NMBs
Surgical prophylaxis: 5 mg/kg IV single preoperative dose on adjusted body weight (adult); 2.5 mg/kg (pediatric). Infuse over 30-60 min.
Binds the bacterial 30S ribosomal subunit, causing misreading of mRNA and irreversible inhibition of protein synthesis; concentration-dependent bactericidal activity.
None (not metabolized)
Renal
Infuse over 30-60 min (never IV push). Extended-interval (once-daily) dosing preferred; monitor levels and renal function with repeated dosing.