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Gentamicin dosing strategies for dogs with subclinical renal dysfunction
1Laboratory of Toxicokinetics, North Carolina State University School of Veterinary Medicine, Raleigh 27606.
Antimicrobial Agents and Chemotherapy
|December 1, 1987
Summary
Reducing gentamicin dosage may decrease kidney damage in patients with renal dysfunction. However, different dosing schedules impact treatment effectiveness and nephrotoxicity risk, with TID dosing potentially being least effective and most toxic.
Area of Science:
- Nephrology
- Pharmacokinetics
- Toxicology
Background:
- Subclinical renal dysfunction increases susceptibility to drug-induced kidney injury.
- Gentamicin is an antibiotic commonly used for bacterial infections, but it carries a risk of nephrotoxicity.
Purpose of the Study:
- To evaluate the nephrotoxic potential of gentamicin across four different dosage regimens in a canine model of subclinical renal dysfunction.
- To assess the impact of dosing strategies on gentamicin pharmacokinetics and potential therapeutic efficacy.
Main Methods:
- Twenty-six subtotally nephrectomized dogs received gentamicin (3.75 mg/kg/day) via two or three divided daily doses (BID, TID) or 2-h/4-h once-daily variable-rate infusions (2HI, 4HI) for 12 days.
- Serum chemistries, histopathology, and pharmacokinetic parameters (including gentamicin clearance) were analyzed by comparing pre- and post-treatment values.
- Population pharmacokinetic modeling predicted time above minimum inhibitory concentrations (MICs) for various pathogens.
Main Results:
- No significant differences in serum chemistries or histopathology indicated toxicity between groups.
- Pharmacokinetic analysis revealed significant differences in the ratio of pre- to post-treatment gentamicin clearance, with TID showing a higher ratio (2.44 +/- 0.52) compared to BID (1.35 +/- 0.22), 2HI (0.91 +/- 0.08), and 4HI (0.91 +/- 0.07).
- Predicted time above MICs varied significantly by regimen, with infusions (2HI, 4HI) generally maintaining concentrations longer than divided doses (BID, TID).
Conclusions:
- Decreasing the total daily dose of gentamicin may reduce the incidence of nephrotoxicity.
- Different gentamicin dosing regimens can significantly impact predicted therapeutic efficacy.
- The TID regimen may be the least efficacious and most prone to future nephrotoxicity due to decreased gentamicin clearance during treatment and lower post-dosing concentrations.