Overview
Gentamicin is an aminoglycoside antibiotic used to treat serious bacterial infections caused by susceptible strains of Gram-negative bacteria. It is bactericidal and works by inhibiting protein synthesis in bacteria.
Mechanism of Action
Binds to the 30S ribosomal subunit, inhibiting bacterial protein synthesis and causing misreading of mRNA, leading to bacterial cell death.
Indications
- Severe infections caused by susceptible Gram-negative organisms (e.g., Pseudomonas, E. coli, Klebsiella)
- Bacterial septicemia
- Meningitis
- Peritonitis
- Respiratory tract infections
- Urinary tract infections
- Skin and soft tissue infections
- Bone and joint infections
- Endocarditis (in combination with other antibiotics)
Dosage
Dosage varies based on infection severity, patient weight, renal function, and route of administration. Typical adult IV/IM dose: 3-5 mg/kg/day in divided doses every 8 hours. Must be adjusted for renal impairment. Monitoring of serum concentrations is recommended.
Contraindications
- Hypersensitivity to gentamicin or other aminoglycosides
- History of serious toxic reactions to aminoglycosides
Side Effects
- Nephrotoxicity (elevated creatinine, reduced urine output)
- Ototoxicity (tinnitus, hearing loss, vertigo)
- Neurotoxicity (headache, lethargy, tremors)
- Nausea, vomiting
- Skin rash, itching
- Injection site reactions
- Peripheral neuropathy
- Muscle weakness
Interactions
- Other nephrotoxic drugs (e.g., vancomycin, amphotericin B, cisplatin): Increased risk of kidney damage
- Other ototoxic drugs (e.g., loop diuretics like furosemide): Increased risk of hearing loss
- Neuromuscular blocking agents (e.g., succinylcholine): Enhanced neuromuscular blockade, risk of respiratory depression
- Penicillins (e.g., ampicillin): Physical incompatibility when mixed in solution, but synergistic against some bacteria