Gentamicin is a type of aminoglycoside antibiotic. It is poorly lipid-soluble and is therefore given parentally (e.g. for infective endocarditis) or topically (e.g. for otitis externa).

Adverse effects

• ototoxicity
  • due to auditory or vestibular nerve damage
  • irreversible
• nephrotoxicity
  • accumulates in renal failure
  • the toxicity is secondary to acute tubular necrosis
  • concomitant use of furosemide increases the risk
  • lower doses and more frequent monitoring is required

Contraindications

• myasthenia gravis

Dosing

• due to the significant ototoxic and nephrotoxic potential of gentamicin it is important to monitor plasma concentrations
• both peak (1 hour after administration) and trough levels (just before the next dose) are measured
• if the trough (pre-dose) level is high the interval between the doses should be increased
• if the peak (post-dose) level is high the dose should be decreased