A type of bactericidal antibiotic active against some gram positive and most gram negative bacteria. This type of natural antibiotic can be modified for lower human toxicity or greater bacterial activity. Some compounds are also active against protozoa. They act on ribosomal transcription.
Poor CNS penetration.
Once daily dosing is preferred as it confers a high peak, which gives the best killing (peak/MIC ratio), and also allows for a drug free period. Aminoglycosides need a drug free period to penetrate bacteria - allows adaptive resistance to fall. This is called the post-antibiotic effect, and in practical terms means a low or undetectable trough (less than 0.5). Hartford nomogram gives dosing interval for adults where once daily dosing is too frequent.
Aminoglycosides have a low volume of distribution so obese patients may get toxic if dosed by weight.
- Impairment neuromuscular transmission
Aminoglycoside ototoxicity is associated with a genetic susceptibility in a third to a half of all cases. Most commonly mitochondrial – shows bacterial origin. Screening patients likely to need repeated courses eg CFs, chemotherapy patients, preterm neonates is feasible, but cost:benefit ratio? Consider costs of deafness, cochlear implant etc.
- Enhanced ototoxicity with ototoxic diuretics eg furosemide.