Kuentz, Martin

Kuentz, Martin


Gerade angezeigt 1 - 2 von 2
  • Publikation
    Investigating oral absorption of carbamazepine in paediatric populations
    (2017) Kohlmann, Philip; Stillhart, Cordula; Parrot, Neil; Kuentz, Martin [in: The AAPS Journal]
    Prediction of the pharmacokinetics of orally administered drugs in children is of importance to optimize the efficacy and safety of pediatric medicines. Physiologically based pharmacokinetic (PBPK) models can be helpful for this purpose. However, application of these tools is limited by significant knowledge gaps regarding the physiological and anatomical changes which occur with age. This study aimed at investigating the age-dependent differences in oral absorption of a poorly soluble model compound, carbamazepine (CBZ) in children, infants, and neonates. We developed an oral absorption model in GastroPlus® and, after evaluation of the PBPK model for adults, extrapolation to younger ages was verified with clinical data and sensitivity analyses were applied for uncertain model parameters. We found that age-based scaling of physiological parameters, with clearance in particular, was important to obtain adequate simulation results. The sensitivity analysis revealed that CBZ absorption was influenced by solubility, particle radius, and small intestinal transit time depending on the pediatric age group and CBZ dose. However, in vitro dissolution testing using proposed pediatric biorelevant media suggested no major age dependency of dissolution kinetics. Such better understanding of oral absorption in pediatric patients is required to improve the prediction of exposure in children and the confidence in oral biopharmaceutical tools.
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  • Publikation
    Using Physiologically Based Pharmacokinetic (PBPK) Modelling to Gain Insights into the Effect of Physiological Factors on Oral Absorption in Paediatric Populations
    (08.07.2016) Villiger, Angela; Stillhart, Cordula; Parrot, Neil; Kuentz, Martin [in: The AAPS Journal]
    Paediatric pharmaceutics has become an important topic, but currently, there is an incomplete knowledge of paediatric gastrointestinal physiology and adequate biopharmaceutical tools still have to be developed. The present study aimed to increase the understanding of oral drug absorption in paediatric populations by using physiologically based pharmacokinetic (PBPK) modelling and in vitro dissolution testing. The oral absorption of two model compounds, sotalol and paracetamol, was studied by collection of reported pharmacokinetic profiles from adult and paediatric subjects. A PBPK model based on input parameters collected from the literature was first developed and validated in adults before being extrapolated to paediatric age groups. The accuracy of the model simulations was assessed by comparison to the observed pharmacokinetic profiles, and in the case of discrepancy, further investigations were made via parameter sensitivity analysis and in vitro dissolution testing. The PBPK models accurately predicted sotalol and paracetamol exposure in adult populations. An accurate simulation was also obtained after model extrapolation to children older than 2 years of age. However, the simulation in infants and newborns resulted in a discrepancy, which was further analysed. Dissolution testing suggested no significant difference in the drug release rate between paediatric and adult age groups. In contrast, mean gastric emptying time seemed to be underestimated in infants and newborns, and optimisation of this input parameter improved the prediction of the model. Considering age-specific differences in gastrointestinal tract physiology should improve prediction of drug absorption in paediatric patients.
    01 - Zeitschriftenartikel, Journalartikel oder Magazin