Injectable Gentamicin Dosage for Urinary Tract Infections
For uncomplicated urinary tract infections, gentamicin should be administered at 5-7 mg/kg/day IV as a single daily dose for 5-7 days. 1
Standard Dosing Recommendations
- For adults with normal renal function and serious UTIs, the FDA-approved dose is 3 mg/kg/day divided into three equal doses every 8 hours 2
- For life-threatening infections, dosages up to 5 mg/kg/day may be administered in three or four equal doses, but should be reduced to 3 mg/kg/day as soon as clinically indicated 2
- For complicated UTIs caused by multidrug-resistant organisms, a higher dose of 5-7 mg/kg/day as a single daily dose is recommended 1
Administration Considerations
- Intravenous administration is particularly useful for patients with bacterial septicemia or those in shock 2
- Intramuscular administration is appropriate for most uncomplicated UTIs 2
- Target peak serum concentrations should be 4-6 mcg/mL (30-60 minutes after IM injection) 2
- Trough concentrations should be maintained below 2 mcg/mL to avoid toxicity 2
Duration of Treatment
- For uncomplicated UTIs: 5-7 days 1
- For complicated UTIs: 7-10 days 2
- Extended treatment beyond 10 days increases risk of toxicity and requires monitoring of renal, auditory, and vestibular functions 2
Special Considerations
- Single daily dosing has shown efficacy for lower UTIs and may be preferred over multiple daily dosing for uncomplicated UTIs 3, 4
- In patients with extensive burns or altered pharmacokinetics, measurement of serum concentrations is recommended as a basis for dosage adjustment 2
- For patients with renal impairment, dosage adjustment is necessary with close monitoring of serum concentrations 5
Monitoring Requirements
- Measure both peak and trough serum concentrations periodically during therapy 2
- Adjust dosage to avoid prolonged levels above 12 mcg/mL (peak) and above 2 mcg/mL (trough) 2
- Monitor renal function throughout treatment course 2
Common Pitfalls and Caveats
- Aminoglycoside dosing in obese patients should be based on an estimate of lean body mass, not total body weight 2
- Nephrotoxicity and ototoxicity are significant concerns with gentamicin therapy, making appropriate dosing and monitoring essential 5
- For patients with reduced muscle mass, congestive heart failure, or hematologic disorders, intravenous administration may be preferred over intramuscular 2
- Resistance patterns should be considered when selecting gentamicin for UTI treatment 1