Vancomycin pharmacokinetics in acute renal failure: preservation of nonrenal clearance.

INTRODUCTION

The normal nonrenal clearance of vancomycin is reduced in patients with chronic renal failure (40 versus 6 ml/min). The nonrenal clearance of vancomycin in patients with acute renal failure has not been characterized extensively.

PURPOSE

To prospectively determine the pharmacokinetic profile of vancomycin in anuric patients with acute renal failure who are receiving continuous venovenous hemofiltration.

METHODS

Vancomycin serum samples were obtained in 10 patients immediately before and 1 and 12 hours after a 1-hour infusion. Thirteen sets of data were obtained. Vancomycin concentration data were incorporated into a first-order, single-compartment model. Determinations for the area under the serum concentration-time curve were made by the trapezoidal rule.

RESULTS

Total vancomycin clearance was 28.5 +/- 6.4 ml/min (range, 17.1 to 36.6 ml/min. Hemofilter clearance was either 6.7 or 13.3 ml/min, depending on ultrafiltrate production rate (assuming a sieving coefficient of 0.8). Nonrenal clearance, calculated as total clearance minus hemofilter clearance was 16.2 +/- 7.0 ml/min (range, 3.8 to 23.3 ml/min). Total clearance did not correlate with hemofilter clearance (r = 0.1; p greater than 0.25) but correlated strongly with nonrenal clearance (r = 0.94; p less than 0.0005). Nonrenal clearance decreased significantly as the days on continuous venovenous hemofiltration increased (range, 2 to 14 days; r = 0.68; p less than 0.025).

CONCLUSION

Early in the course of acute renal failure there is a substantial preservation of the normal nonrenal clearance of vancomycin. This nonrenal clearance appears to decrease with the duration of renal failure, eventually approaching the clearance observed in patients with chronic failure.