RESUMO
The pharmacokinetics (PK) of amoxicillin in asphyxiated newborns undergoing moderate hypothermia were quantified using prospective data (N = 125). The population PK was described by a 2-compartment model with a priori birthweight (BW) based allometric scaling. Significant correlations were observed between clearance (Cl) and postnatal age (PNA), gestational age (GA), body temperature (TEMP), and urine output (UO). For a typical patient with GA 40 weeks, BW 3,000 g, 2 days PNA (i.e., TEMP 33.5°C), and normal UO, Cl was 0.26 L/h (interindividual variability (IIV) 41.9%) and volume of distribution of the central compartment was 0.34 L/kg (IIV of 114.6%). For this patient, Cl increased to 0.41 L/h at PNA 5 days and TEMP 37.0°C. The respective contributions of both covariates were 23% and 27%. Based on Monte Carlo simulations we recommend 50 and 75 mg/kg/24h amoxicillin in three doses for patients with GA 36-37 and 38-42 weeks, respectively.
Assuntos
Amoxicilina/farmacocinética , Antibacterianos/farmacocinética , Hipotermia/metabolismo , Envelhecimento/metabolismo , Algoritmos , Amoxicilina/administração & dosagem , Antibacterianos/administração & dosagem , Peso ao Nascer , Temperatura Corporal , Estudos de Coortes , Simulação por Computador , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Método de Monte Carlo , Estudos Prospectivos , UrodinâmicaRESUMO
To date, morphine pharmacokinetics (PKs) are well quantified in neonates, but results about its efficacy are ambiguous. This work presents an analysis of a previously published study on pain measurements in mechanically ventilated preterm neonates who received either morphine or placebo to improve comfort during invasive ventilation. The research question was whether morphine reduces the pain associated with endotracheal or nasal suctioning before, during, and after suctioning. Because these neonates cannot verbalize their pain levels, pain was assessed on the basis of several validated pain measurement instruments (i.e., COMFORT-B, preterm infant pain profile [PIPP], Neonatal Infant Pain Scale (NIPS), and visual analogue scale (VAS)). The item response theory (IRT) was used to analyze the data in order for us to handle the data from multiple-item pain scores. The analysis showed an intra-individual relationship between morphine concentrations and pain reduction, as measured by COMFORT-B and VAS. However, the small magnitude of the morphine effect was not considered clinically relevant for this intervention in preterm neonates.
