Pharmacokinetics of vancomycin during continuous hemodiafiltration

Abstract

Objective: To study the pharmacokinetics of vancomycin in three patients with acute renal failure related to multi-organ failure during continuous venovenous hemodiafiltration (CVVHD).

Design: Prospective exploratory, open-labelled study.

Setting: Critical Care Unit in a University Medical Centre.

Patients: 3 patients exhibiting hemodynamic instability and oligo-anuric acute renal failure requiring extra-renal epuration were included in this study.

Intervention: Every patient received 7.5 mg/kg IV vancomycin over 1 h for a documented or suspected nosocomial staphylococcal infection. Serum and dialysate outlets samples were collected before infusion and 1, 3, 6, 12, 18, 24 after the end of infusion.

Measurements and results: Mean age was 58.7 years (range 41-79) and mean SAPS 15.7 (9-23). The mean peak concentrations were 27.3 mg/l (range 15.6-45.6) one hour after the end of infusion. The average remaining vancomycin concentration 24 h after the onset of infusion was 3.6 mg/l (range 2.6-4.5). The mean terminal disposition rate constant and elimination half-life were 0.05 h-1 and 13.9 h respectively. Mean total body clearance was 38.9 +/- 4.3 ml/min and dialysate outlet (DO) clearance 4.2 +/- 1.3 ml/min. The mean volume of distribution was 47.4 +/- 6.4 l.

Conclusion: CVVHD is effective for vancomycin elimination. In these patients, the elimination half-life is almost constant, involving a following injection of vancomycin 12 h later to achieve effective concentrations.