Introduction

Aminoglycosides are a type of antibiotic, of which gentamicin is the most widely used. They are poorly lipid soluble and are therefore given parentally (e.g. for infective endocarditis) or topically (e.g. for otitis externa).

Mechanism of action

Aminoglycosides inhibit protein synthesis by disturbing peptide elongation at the 30S ribosomal subunit

Adverse effects

  • Ototoxicity: irreversible, due to auditory or vestibular nerve damage
  • Nephrotoxicity: accumulates in renal failure, lower doses and more frequent monitoring is required

Contraindications

Myasthenia gravis

Monitoring

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