RESUMO
Asphyxiated neonates often undergo therapeutic hypothermia (TH) to reduce morbidity and mortality. Since both perinatal asphyxia (PA) and TH influence physiology, altered pharmacokinetics (PK) and pharmacodynamics (PD) are expected. Given that TH is the standard of care for PA with moderate to severe hypoxic-ischemic encephalopathy (HIE), disentangling the effect of PA versus TH on PK/PD is not possible in clinical settings. However, animal models can provide insights into this matter. The (neonatal) Göttingen Minipig, the recommended strain for nonclinical drug development, was selected as translational model. Four drugs - midazolam (MDZ), fentanyl (FNT), phenobarbital (PHB), and topiramate (TPM), were intravenously administered under four conditions: control (C), therapeutic hypothermia (TH), hypoxia (H), hypoxia + TH (H+TH). Each group included six healthy male neonatal Göttingen Minipigs anesthetized for 24 hours. Blood samples were drawn at 0 (pre-dose), and 0.5, 2, 2.5, 3, 4, 4.5, 6, 8, 12, 24 hours post-drug administration. Drug plasma concentrations were determined using validated bioanalytical assays. The PK parameters were estimated through compartmental and non-compartmental PK analysis (NCA). The study showed a statistically significant decrease in FNT clearance (CL, 66% decrease) with approximately 3-fold longer half-life (t1/2) in the TH group. The H+TH group showed a 17% reduction in FNT CL with a 62% longer t1/2 compared to the C group, however non-statistically significant. Trends towards lower CL and longer t1/2 were observed in the TH and H+TH groups for MDZ and PHB. Additionally, TPM demonstrated a 28% decrease in CL in the H group compared to controls. Significance Statement The overarching goal of this study using the neonatal Göttingen Minipig model was to disentangle the effects of systemic hypoxia and TH on PK, using four model drugs. Such insights can subsequently be used to inform and develop a physiologically-based pharmacokinetic (PBPK) model, which is useful for drug exposure prediction in human neonates.
RESUMO
Women commonly take medication during lactation. Currently, there is little information about the exposure-related safety of maternal medicines for breastfed infants. The aim was to explore the performance of a generic physiologically-based pharmacokinetic (PBPK) model to predict concentrations in human milk for ten physiochemically diverse medicines. First, PBPK models were developed for "non-lactating" adult individuals in PK-Sim/MoBi v9.1 (Open Systems Pharmacology). The PBPK models predicted the area-under-the-curve (AUC) and maximum concentrations (Cmax) in plasma within a two-fold error. Next, the PBPK models were extended to include lactation physiology. Plasma and human milk concentrations were simulated for a three-months postpartum population, and the corresponding AUC-based milk-to-plasma (M/P) ratios and relative infant doses were calculated. The lactation PBPK models resulted in reasonable predictions for eight medicines, while an overprediction of human milk concentrations and M/P ratios (>2-fold) was observed for two medicines. From a safety perspective, none of the models resulted in underpredictions of observed human milk concentrations. The present effort resulted in a generic workflow to predict medicine concentrations in human milk. This generic PBPK model represents an important step towards an evidence-based safety assessment of maternal medication during lactation, applicable in an early drug development stage.
RESUMO
The hypothesis of this study is that fisetin and phase II conjugated forms of fisetin may partly undergo biliary excretion. To investigate this hypothesis, male Sprague-Dawley rats were used for the experiment, and their bile ducts were cannulated with polyethylene tubes for bile sampling. The pharmacokinetic results demonstrated that the average area-under-the-curve (AUC) ratios ( k (%) = AUCconjugate/AUCfree-form) of fisetin, its glucuronides, and its sulfates were 1:6:21 in plasma and 1:4:75 in bile, respectively. Particularly, the sulfated metabolites were the main forms that underwent biliary excretion. The biliary excretion rate ( kBE (%) = AUCbile/AUCplasma) indicates the amount of fisetin eliminated by biliary excretion. The biliary excretion rates of fisetin, its glucuronide conjugates, and its sulfate conjugates were approximately 144, 109, and 823%, respectively, after fisetin administration (30 mg/kg, iv). Furthermore, biliary excretion of fisetin is mediated by P-glycoprotein.
