Development and external evaluation of a population pharmacokinetic model for continuous and intermittent administration of vancomycin in neonates and infants using prospectively collected data.

BACKGROUND: Vancomycin is commonly used for nosocomial bacterial pathogens causing late-onset septicaemia in preterm infants. We prospectively collected pharmacokinetic data aiming to describe pharmacokinetics and determine covariates contributing to the variability in neonatal vancomycin pharmacokinetics. Further, we aimed to use the model to compare the ratio of AUC24 at steady-state to the MIC (AUC24,ss/MIC) of several intermittent and continuous dosing regimens. METHODS: Newborns receiving vancomycin for suspected or confirmed late-onset sepsis were included. Peak and trough concentrations for intermittent vancomycin dosing and steady-state concentrations for continuous vancomycin dosing were measured. NONMEM 7.3 was used for population pharmacokinetic analysis. Monte Carlo simulations were performed to compare dosing schemes. RESULTS: Data from 54 infants were used for model development and from 34 infants for the model evaluation {corrected gestational age [median (range)] = 29 (23.7-41.9) weeks and 28 (23.4-41.7) weeks, respectively}. The final model was a one-compartment model. Weight and postmenstrual age were included a priori, and then no additional covariate significantly improved the model fit. Final model parameter estimates [mean (SEM)]: CL = 5.7 (0.3) L/h/70 kg and V = 39.3 (3.7) L/70 kg. Visual predictive check of the evaluation dataset confirmed the model can predict external data. Simulations using MIC of 1 mg/L showed that for neonates with gestational age ≤25 weeks and postnatal age ≤2 weeks AUC24,ss/MIC was lower with the intermittent regimen (median 482 versus 663). CONCLUSIONS: A population pharmacokinetic model for continuous and intermittent vancomycin administration in infants was developed. Continuous administration might be favourable for treating infections caused by resistant microorganisms in very young and immature infants.

Hypersensitivity reaction to components of parenteral nutrition in pediatrics.

Very rare cases of hypersensitivity reactions to various constituents of parenteral nutrition (PN) have been reported in children. Adverse effects associated with PN administration have centered on metabolic, infectious, and mechanical complications. Here we describe three cases of hypersensitivity to components of PN. Case 1 is a 1-mo-old breastfed baby with a diagnosis of acute gastroenteritis associated with an infection with cytomegalovirus. On the second day of PN, 60 min after the initiation of the infusion, the patient had an allergic reaction with an overall diffused rash. On day 4 of PN, the multivitamin solution and the trace element mix were excluded, showing a good tolerance. Case 2 is a 4-y-old girl with a background of stage III neuroblastoma. On day 3 of PN, 15 min after the initiation of the infusion, the patient showed sudden facial edema. On day 5, suspecting the amino acid solution to be the etiology of her reaction, PN was infused with another amino acid preparation, and the patient showed good tolerance. Case 3 is a 10-y-old boy with a diagnosis of an acute peritonitis. Two h after the initiation of the infusion, the patient showed a general wheal rash. He referred a background of fish allergy. Considering that the lipid emulsion used had components from fish oil (SMOF Lipid), a new PN was infused on day 2. The new PN contained a lipid emulsion containing vegetable oil (ClinOleic). The patient showed good tolerance. In conclusion, we consider that, although the hypersensitivity to PN components is infrequent, there is an increase in reports of pediatric cases describing this allergic pathology.