Gentamicin

Emma Farrell

UNDER REVIEW (September 2016)

Mechanism of Action:

An aminoglycoside. Aminoglycosides act by binding irreversibly to the 30S subunit of the bacterial ribosome, inhibiting bacterial protein synthesis and generating errors in transcription of the genetic code.

Lecture and CAL materials:

Drug specifics

Alternative drug name not specified
Effects Aminoglycosides are bactiricidal against Gram negative bacilli and gentamicin has active against Staph. Aureus. Most Gram positive organisms and anaerobes are resistant to aminoglycosides. Used for Gram negative infections (eg. bowel, urinary and biliary) and severe Staph. Aureus. infection.
Adverse actions The adverse effects of these drugs include ototoxicity (cumulative, irreversible) - streptomycin and gentamicin affect predominantly the vestibular nerves (causing dizziness and vertigo), whereas kanamycin and neomycin affect predominantly the auditory nerves (causing high tone deafness) - nephrotoxicity (reversible in early stages), and neuromuscular blockade (can provoke severe respiratory depression). The ototoxic and nephrotoxic effects can be minimized by careful monitoring of serum aminoglycoside concentration. The aim is to ensure that peak (1 hour after the dose)and trough (immediately pre-dose) concentrations are not excessive. The use of gentamicin is complex and potentially hazardous and is best undertaken with specialist advice.
Dose See eBNF.
Interactions The toxic effects of aminoglycosides are increased by concurrent use of other nephrotoxic drugs, such as cephalosporins, ciclosporin and cisplatin, and by other ototoxic drugs, such as furosemide (frusemide), especially when administered at high dosage intravenously. See eBNF.
Contraindications not specified
Comments Aminoglycosides are antimicrobials derived from bacteria of the genus Streptomyces (kanamycin, neomycin, streptomycin, tobramycin) and the genus Micromonospora (gentamicin). Streptomycin was the first drug used to treat tuberculosis but has been superceded. Aminoglycosides are poorly absorbed from the gastrointestinal tract and are usually given parenterally. Netilmicin and amikacin are reserved for infections that are resistant to treatment with other aminoglycosides.
Contributors