Difference in nephrotoxicity of vancomycin administered once daily and twice daily in rats.

We compared the degree of nephrotoxicity of vancomycin (VCM) administered once daily and twice daily in rats. VCM was intraperitoneally administered once daily to rats at a dose of 400 mg/kg (VCM-1-treated) or administered at a dose of 200 mg/kg twice daily at 12-hour intervals (VCM-2-treated) for 7 consecutive days. Creatinine clearance was decreased more markedly in VCM-1 rats relative to VCM-2 rats, although there was no significant difference in renal accumulation of VCM between the two groups. Renal superoxide dismutase activity was lower in VCM-1 rats than that in VCM-2 rats. The magnitude of histological change in kidney tissue was in agreement with the degree of alterations in the abovementioned biochemical values. These results suggest that the nephrotoxic effect of once-daily VCM administration is more pronounced than that of the twice-daily treatment. Our findings provide fundamental evidence for the advantage in choosing a divided VCM administration to attenuate nephrotoxicity.