Overview
Tobramycin is an aminoglycoside antibiotic used to treat serious bacterial infections caused by susceptible gram-negative organisms, including Pseudomonas aeruginosa, Escherichia coli, and Klebsiella species. It works by inhibiting bacterial protein synthesis, making it effective against aerobic gram-negative bacilli. Due to its potential for nephrotoxicity and ototoxicity, it is reserved for severe infections where less toxic alternatives are ineffective or contraindicated.
Mechanism of Action
Tobramycin binds to the 30S ribosomal subunit of susceptible bacteria, inhibiting protein synthesis and causing misreading of mRNA, which leads to bacterial cell death. It is bactericidal against aerobic gram-negative organisms.
Indications
- Serious bacterial infections caused by susceptible organisms
- Septicemia in neonates, children, and adults
- Lower respiratory tract infections
- Central nervous system infections (meningitis)
- Intra-abdominal infections including peritonitis
- Skin, bone, and skin structure infections
- Complicated and recurrent urinary tract infections
- Serious staphylococcal infections when less toxic drugs are contraindicated
Common Doses
- Varies by indication and patient factors; typically 3-5 mg/kg/day in divided doses every 8 hours
- Dosage adjustment required for renal impairment
Dosage
Administered intramuscularly or intravenously with dosage based on patient's pretreatment body weight. Recommended dosages are the same for both routes. Monitoring of peak and trough serum concentrations is essential to minimize toxicity.
Contraindications
- Hypersensitivity to any aminoglycoside
- History of serious toxic reactions to aminoglycosides
Side Effects
- Nephrotoxicity
- Ototoxicity (hearing loss, tinnitus, vertigo)
- Neurotoxicity
- Neuromuscular blockade
- Allergic reactions
- Gastrointestinal disturbances
- Hematologic abnormalities
Interactions
- Enhanced nephrotoxicity with other nephrotoxic drugs (e.g., cisplatin, vancomycin)
- Enhanced ototoxicity with other ototoxic drugs
- Neuromuscular blockade potentiated by anesthetic agents or neuromuscular blocking agents
- Synergistic activity with beta-lactams against certain organisms
Counseling Points
- Complete full course of therapy even if symptoms improve
- Report any hearing changes, ringing in ears, dizziness, or balance problems
- Maintain adequate hydration during treatment
- Inform healthcare provider of all medications being taken
- Report severe diarrhea or abdominal pain during or after treatment