#50: Vancomycin Doses and Trough Concentrations in Pediatric Patients

Background Vancomycin serum trough concentrations are monitored to reduce nephrotoxicity and optimize therapeutic efficacy. Vancomycin pharmacokinetics and trough levels used in pediatric patients are extrapolated from the adult population. The pediatric dosing strategies are empirical and there is limited evidence to suggest that these doses result in the recommended steady-state trough concentrations. The objective of the study was to determine the association between vancomycin dosing regimens and trough concentrations levels of 10 to 20 μg/mL in pediatric patients with complicated infections. Methods Retrospective cohort, 505 trough vancomycin serum concentrations of patients of 1 month to 18 years from hospital wards and the Intensive Care Unit of the Instituto Nacional de Salud del Niño San Borja during December 2015 to April 2019. It included only the first vancomycin trough level measured 30 minutes before the fourth doses and serum trough concentrations of 10 to 20 μg/mL were considered as therapeutic levels. A multinomial logistic regression model to estimate the relative risk ratio (RRR) with a 95% confidence interval was used, the comparator group was therapeutic vancomycin levels and it was adjusted by glomerular filtration rate, age group, hospital room, dose interval, and weight. Results Five hundred and five vancomycin dosages were analyzed. Infants and children were 43.12% and 39.22%, respectively, 45.17% were women. 56.77% had a high glomerular filtration rate and only 28.02% of the patients obtained therapeutic trough levels of vancomycin. The RRR of having sub-therapeutic levels in patients with low glomerular filtration rates compared with normal filtration rates was 0.31 (P = 0.049) and the RRR of having sub-therapeutic levels in patients from 2 to 12 years compared with patients under 2 years old was 2.38 (P = 0.007). There was no difference in having therapeutic levels using doses equal or greater than 60 mg/kg/day vs. less than 40 mg/kg/day comparing sub-therapeutic levels (P = 0.655) and supratherapeutic levels (P = 0.264). Conclusions The empirical vancomycin regimens used in pediatric patients did not reach the recommended therapeutic trough levels of 10 to 20 μg/mL. Patients of 2 to 12 years and low glomerular filtration rates were associated to have sub-therapeutic trough levels.