Evaluation of Vancomycin Dosing in Pediatric Cystic Fibrosis Patients.

Objectives: The presence of methicillin-resistant Staphylococcus aureus (MRSA) in cystic fibrosis (CF) patients' sputa is associated with a decline in pulmonary function and increased mortality. Vancomycin is the preferred treatment for MRSA pneumonia in children. No published studies have evaluated the vancomycin dose needed to achieve goal vancomycin trough concentrations (VTCs; 15-20 mg/L) in pediatric patients with CF. The primary objective is to determine whether a vancomycin dosage of 60 mg/kg/day achieves a goal VTC in pediatric CF patients. Secondary objectives include determining the average dosage required to reach a goal VTC and the impact of achieving a goal VTC on estimated glomerular filtration rate (eGFR) and pulmonary function.

Methods: A retrospective review of pediatric patients with CF who received vancomycin was conducted.

Results: A total of 90 vancomycin treatment courses were analyzed. Standard vancomycin dosing (60 mg/kg/day) achieved goal VTC in 11 courses (12.2%). The mean dosage required to achieve a goal VTC for all courses was 70.6 ± 16.7 mg/kg/day. Patients who achieved goal VTCs were more often older, weighed more, and had higher serum creatinine concentrations at therapy initiation. On average, a dosage of 70.6 mg/kg/day was required to achieve a goal VTC. Despite dosages up to 120 mg/kg/day, no significant changes in renal function occurred. Achieving a goal VTC had no significant impact on eGFR or pulmonary function during therapy.

Conclusions: Vancomycin dosing of 60 mg/kg/day does not reliably achieve a VTC of 15 to 20 mg/L in pediatric CF patients. Younger CF patients may require higher vancomycin doses.