Gentamicin is a bactericidal amino glycoside antibiotic, which acts by inhibiting protein synthesis of susceptible bacteria. It is effective against a wide variety of pathogenic aerobic gram-negative bacilli and some gram-positive organisms. It is not active against anaerobic organisms.
Gentamicin injection is indicated in the treatment of serious infections caused by susceptible strains of the following microorganisms: Pseudomonas aeruginosa, Proteus species (indole positive and indole negative) Escherichian coli, Klebsiella- Enterobacter – Serratia species, Staphylococcus species (coagulase positive and coagulase negative), Septicemia, Respiratory tract infections, infected wounds, bones and soft tissue infections including peritonitis, septic abortion and burns complicated by sepsis, Urinary tract infections (recurrent, complicated)
Gentamicin is contraindicated in patients with history of hypersensitivity to Gentamicin, other amino glycoside or any constituents of the injection, as well as in patients who have experienced serious toxic reactions (ototoxicity or nephrotoxicity) to Gentamicin or to other amino glycoside therapy
Use in pregnancy: category D
Gentamicin and other amino glycosides are known to cross the placenta. There is evidence of selective uptake of Gentamicin by the fetal kidney resulting in cellular damage (probably reversible) to immature nephrons. Because of their chemical similarity, amino glycosides must be considered potentially nephrotoxic and ototoxic to the foetus. It should also be noted that therapeutic blood levels in the mother do not equate with safety for the foetus.
Dosage and administration
Gentamicin is given by the intramuscular route or intravenously. Intravenous administration: for IV administration, the prescribed dose of Gentamicin may be diluted in 100 – 200 ml of sterile normal saline or 5% glucose in water. The concentration of Gentamicin in the solution should not exceed 1mg/ml. infusion periods of 30 minutes to 2 hours have been advocated. Administration of the dose by bolus injection produces serum levels, which are initially in excess of what is regarded as being safe from toxic side effects. The high serum level does however rapidly fail and the potential danger or safety of this method of administration is yet to be established.
Peritoneal dialysis or haemodialysis will aid in the removal of Gentamicin from the blood. This is particularly important in patients with renal malfunction.
Nephrotoxicity, neurotoxicity, symptoms include dizziness, vertigo, tinnitus, roaring in the ears and hearing loss, which as with the other amino glycosides may be irreversible. Peripheral neuropathy or encephalopathy, including numbness, skin tingling, muscle twitching, convulsions and myasthenia gravis – like syndrome has been reported.