Use of Individual Pharmacokinetics to Improve Time to Therapeutic Vancomycin Trough in Pediatric Oncology Patients.

Objective: Optimization of vancomycin dosing is difficult in children, given rapid drug clearance and patient heterogeneity. We sought to evaluate the impact of dosing using individual pharmacokinetic parameters on time to goal trough concentration in pediatric oncology patients.

Methods: A retrospective review was conducted to assess vancomycin dosing in the pediatric oncology unit at Loma Linda University Children's Hospital between January 2013 and August 2013 (standard dosing group [SDG]). These patients were compared to those in a prospective arm that used pharmacokinetic dosing (pharmacokinetic dosing group [PKG]) between March 2014 and May 2015. Outcomes included percent of patients reaching a target trough by the specified time points, number of dose adjustments, number of serum concentrations drawn, and number of patients with supratherapeutic troughs.

Results: Of 35 patients meeting inclusion criteria for the SDG, 2 (5.7%) reached goal trough concentration by 48 hours, compared with 14 of 16 patients (87%) in the PKG (p = 0.0001). Significantly more patients reached their goal trough at each time point in the PKG. There was no difference in number of dose adjustments, but significantly more concentrations were drawn on average in the PKG (mean, 4.6 versus 3.1, p = 0.02). In the SDG and PKG, respectively, 1 patient and 3 patients had supratherapeutic trough concentrations (p = 0.09).

Conclusions: Dosing using individual pharmacokinetic parameters led to a significant reduction in time to attain the desired vancomycin trough concentration in our pediatric oncology patients. Given the wide variation in dose requirements in this and other studies, application of patient-specific pharmacokinetics is essential to optimize vancomycin dosing in pediatric patients.