ArticlesVancomycin Pharmacokinetics and Bayesian Estimation in Pediatric PatientsWrishko, Rebecca E.*† ; Levine, Marc*† ; Khoo, Dominique† ; Abbott, Phyllis†; Hamilton, Don†Author Information *Faculty of Pharmaceutical Sciences, University of British Columbia, †Department of Pharmacy, Children's and Women's Health Centre of British Columbia, Vancouver, British Columbia. Received April 12, 2000; accepted June 27, 2000. Address correspondence and reprint requests to Marc Levine, Ph.D., Faculty of Pharmaceutical Sciences, University of British Columbia, 2146 East Mall, Vancouver, British Columbia, Canada V6T 1Z3, Therapeutic Drug Monitoring: October 2000 - Volume 22 - Issue 5 - p 522-531 Buy Abstract The vancomycin pharmacokinetic profile was characterized in six pediatric patients and the potential of nonlinear mixed effects modeling and Bayesian forecasting for vancomycin monitoring was explored using NONMEM V (1.1). Based on steady state serial vancomycin concentrations, the estimates of mean t½, Vd, and Cl derived by the Sawchuk and Zaske method (1) were 3.52 hours, 0.57 L/kg, and 0.12 L/h per kg, respectively. NONMEM analysis demonstrated that a weight-adjusted two-compartment model described individual patients' data better than a comparable one-compartment model. The two-compartment estimates of mean t½α, t½β, Vss, and Cl were 0.80 hour, 5.63 hours, 0.63 L/kg, and 0.11 L/h per kg, respectively. The relatively long mean t½α suggests that peak vancomycin concentrations measured earlier than 4 hours postdose do not reflect postdistributional serum concentrations. NONMEM population modeling revealed that a weight-adjusted two-compartment model provided a better fit than a comparable one-compartment model. The resulting population parameters and variances were fixed in NONMEM to obtain Bayesian predictions of individual vancomycin serum concentrations. Bayesian estimation with either a single midinterval or trough sample has the potential to provide accurate and precise predictions of vancomycin concentrations. This should be evaluated using a vancomycin population pharmacokinetic model based on a larger sample of pediatric patients. © 2000 Lippincott Williams & Wilkins, Inc.