Prospective comparative study of variable dosage and variable frequency regimens for administration of gentamicin

Area of Science:

• Pharmacology
• Nephrology
• Clinical Pharmacy

Background:

• Gentamicin dosage requires careful adjustment in patients with impaired renal function to balance therapeutic efficacy and minimize toxicity.
• Two primary dosing regimens exist: variable frequency regimen (VFR) and variable dosage regimen (VDR).

Purpose of the Study:

• To compare the pharmacodynamic characteristics and nephrotoxicity risks of VFR and VDR in seriously ill hospitalized patients with renal impairment.

Main Methods:

• A prospective, randomized study involving 20 seriously ill patients (10 on VFR, 10 on VDR).
• Serum gentamicin levels (peak and trough) and serum creatinine were monitored.
• Correlation between gentamicin trough levels and renal function was analyzed.

Main Results:

• Significant variability in peak gentamicin serum levels was noted.
• Gentamicin trough levels correlated with serum creatinine in the VDR group but not in the VFR group.
• High gentamicin trough levels (> /=4 mug/ml) were frequently observed in both regimens and correlated with renal insufficiency development or progression.

Conclusions:

• Neither VFR nor VDR demonstrated a difference in the risk of nephrotoxicity.
• High gentamicin trough levels are a significant risk factor for nephrotoxicity, irrespective of the regimen used.
• Further studies are required to directly compare the therapeutic efficacy of VFR and VDR.