User Tools

Site Tools


aminoglycosides

aminoglycoside antibiotics

see also;

introduction

  • bactericidal group originally obtained from Streptomyces species
  • ototoxic & nephrotoxic if high dose or prolonged use
  • active mainly against enteric Gram -ve bacteria
  • uses: septicaemia, endocarditis
  • topical agents (these also active against Gram +ves but not Strept)
    • eg. neomycin, framycetin, kanamycin
  • anti-tuberculous:
    • eg. streptomycin

examples

  • Gentamicin:
    • wide Gram -ve spectrum incl. Pseudomonas aeruginosa
    • aminoglyc. of choice for most hosp. acquired aerobic Gram -ve sepsis
  • Tobramycin:
    • marginally more antipseudomonal than gentamicin
    • restricted use & ? if suspected pseudomonal sepsis;
  • Netilmicin:
    • more resistant to enzymatic degradation than genta/tobramycin
  • Amikacin:
    • most resistant to enzymatic degradation - 20x more costly than gentamicin
    • reserved for resistant cases only
  • Streptomycin:
    • available under SAS for Rx of TB.

once daily dosing:

  • Recent studies seem to indicate benefit in single daily doses for following reasons:
    1. higher conc. result in more rapid & extensive killing
    2. selection of resistant mutants during Rx less likely with higher conc.
    3. produce signif. post-antibiotic growth suppression effects even after brief exposure
    4. efficacy determined by area-under-curve of drug exposure, not time conc.>MIC
    5. nephrotoxicity & renal accumulation reduced with higher doses administered daily.
  • However, few studies using gentamicin or tobramycin & limited experience with pts with severe renal impairment (CRN > 300umol/L), febrile neutropenic sepsis, endocarditis or in paediatric pts. In addition, insufficient evidence for risks of ototoxicity.
  • Thus, may be reasonable to use the following single daily doses in adult pts <80yrs old with normal & stable renal function who are likely to be Rx for short periods (<7days):
    • gentamicin 4-5mg/kg
    • netilmicin 4.5mg/kg
    • amikacin 15mg/kg
    • These doses should be given as a 30min infusion.
    • No need for peak levels but check trough levels at least once:
    • Troughs should be less than 0.5mg/L gentamicin & netilmicin, & <5mg/L amikacin.
aminoglycosides.txt · Last modified: 2011/12/01 17:19 (external edit)