Both tyrosine kinase inhibitors (tki) and mammalian target of rapamycin (mTOR) inhibitors are oral targeted therapies that are used for the treatment of a variety of malignancies. Due to the... Show moreBoth tyrosine kinase inhibitors (tki) and mammalian target of rapamycin (mTOR) inhibitors are oral targeted therapies that are used for the treatment of a variety of malignancies. Due to the growing evidence for drug exposure-response relationships, in combination with their high interpatient variability in pharmacokinetics (pk) and a fixed dosing regimen, it is hypothesized that dose individualization of oral targeted therapies may lead to better treatment outcomes both in terms of efficacy as well as toxicity. This thesis describes the results of different studies that investigated dose optimization strategies of oral targeted therapies used in oncology, with a focus on the TKIs pazopanib and sunitinib and the mTOR inhibitor everolimus. Show less
This thesis describes the potential role of non-invasive measurement of pharmacokinetics (pk) and pharmacodynamics (pd) in the research and development of central nervous system (cns) stimulants or... Show moreThis thesis describes the potential role of non-invasive measurement of pharmacokinetics (pk) and pharmacodynamics (pd) in the research and development of central nervous system (cns) stimulants or depressants for children and adolescents. First, we evaluated the feasibility of using saliva as an alternative to plasma in two studies on psychostimulants (caffeine and methylphenidate). Second, neuropsychological and neurophysiological functions were measured longitudinally using the NeuroCart, a battery of tests developed at the Centre for Human Drug Research (chdr, Leiden, The Netherlands) that includes non-invasive tests for alertness, visuomotor coordination, motor control, memory, and subjective drug effects. Using a non-invasive approach, age-dependent differences in alcohol pk and pd were evaluated between healthy adolescents and adults. This thesis concludes with the report of two clinical trials that were designed to evaluate age-appropriate formulations of sedative drugs that have the potential for use in children. Show less
Kleinloog, D.; Stevens, J.; Heuberger, J.; Spinhoven, P.; Gerven, J. van 2014
This thesis focuses on the implications of empirical evidence generation for the evaluation of safety and toxicity during drug development. A shift in paradigm is proposed to 1) ensure that... Show moreThis thesis focuses on the implications of empirical evidence generation for the evaluation of safety and toxicity during drug development. A shift in paradigm is proposed to 1) ensure that pharmacological concepts are incorporated into the evaluation of safety and toxicity; 2) facilitate the integration of historical evidence and thereby the translation of findings across species; and 3) promote the use of experimental protocols tailored to address specific safety and toxicity questions. Nonlinear-mixed effects modelling is recommended as a tool to account for such requirements. Our goal was to explore the feasibility of a model-based approach to toxicology assessment and risk prediction in humans and, where possible, to compare the performance of this approach to traditional safety assessment approaches. The investigational plan of the thesis was divided into two sections where the development of methodology is followed by a case study with real data. A variety of analysis strategies and protocol designs are investigated where we set the constraint that proposals to deviate from existing protocols be minimal. We finally compile recommendations for protocol optimisation and data analysis/interpretation strategies to facilitate the implementation of model-based techniques in safety pharmacology and toxicology research Show less
Pharmacotherapy plays an essential role in an allogeneic hematopoietic stem cell transplantation (allo-HSCT) procedure. Busulfan and treosulfan are two alkylating agents often applied in the... Show morePharmacotherapy plays an essential role in an allogeneic hematopoietic stem cell transplantation (allo-HSCT) procedure. Busulfan and treosulfan are two alkylating agents often applied in the conditioning regimen administered prior to the allo-HSCT. Finding the right balance between efficacious conditioning and toxicity remains the challenge for both agents. A majore One of the major complications after allo-HSCT is Acute graft-versus-host disease (aGvHD). When patients are diagnosed with grade 2 or higher aGvHD, systemic treatment with high-dose glucocorticoids is started as first line treatment. However, only half of the patients respond adequately to this therapy and also in other diseases non-responsiveness to glucocorticoids has been observed. Optimization of current drug therapies in allo-HSCT holds the potential to improve the outcome and safety. The goal of this thesis is to optimize busulfan- and treosulfan-based conditioning regimens and acute GvHD treatment with glucocorticoids by applying pharmacokinetic and pharmacogenetic profiling. Studies are performed in adults and pediatric patients. Show less
De neurotransmitter dopamine speelt een essenti_le rol in diverse neurofysiologische functies en is betrokken bij de pathofysiologie van diverse neuropsychiatrische aandoeningen, waaronder de... Show moreDe neurotransmitter dopamine speelt een essenti_le rol in diverse neurofysiologische functies en is betrokken bij de pathofysiologie van diverse neuropsychiatrische aandoeningen, waaronder de ziekte van Parkinson, schizofrenie, drugsverslaving en hyperprolactinemie. De huidige farmacotherapeutische methoden om dopaminerge neurotransmissie te be_nvloeden, hebben slechts een beperkt effect op de symptomen, terwijl hinderlijke bijwerkingen kunnen optreden. Derhalve heeft verbetering van de farmacotherapie van deze ziekten een hoge prioriteit. De bevindingen van studies in dit proefschrift en followup studies tonen aan dat verbetering van de kinetiek van het geneesmiddel ter plaatse van de receptor en verbetering van de selectiviteit van het geneesmiddel veelbelovende strategie_n zijn. De resultaten van be_nvloeding van de controle mechanismen door tachykinines en gaba lijken vooralsnog minder therapeutisch nut op te leveren, maar geven wel indicaties voor biologische effecten die verder onderzoek verdienen. Deze onderzoekslijnen geven aan dat, ondanks de grote verscheidenheid aan beschikbare dopamine agonisten en antagonisten, de therapeutische mogelijkheden om dopamine neurotransmissie te be_nvloeden nog lang niet verzadigd zijn Show less
Renal clearance is responsible for the elimination of a large number of water-soluble drugs and metabolites and is therefore of large importance when characterizing the pharmacokinetics of drugs.... Show moreRenal clearance is responsible for the elimination of a large number of water-soluble drugs and metabolites and is therefore of large importance when characterizing the pharmacokinetics of drugs. Renal clearance includes glomerular filtration, tubular secretion and reabsorption and each of these processes is subject to different developmental changes. To estimate the renal clearance of drugs in children, a thorough understanding of these developmental changes in the different subprocesses contributing to renal function is needed. Therefore the aim of the research described in this thesis was to characterize the developmental changes in renal function over the entire pediatric age range. To this end, a system-based pharmacology approach was applied implicating that within the models for the different subprocesses contributing to renal function a distinction was made between system-specific and drug-specific properties. The transition to a more system-based pharmacology approach and the combination of different strategies (extrapolation to other drugs, adult data or non-clinical data) will result in an approach focusing on the underlying system instead of focusing on the drugs and may facilitate development of pharmacokinetic models and evidence-based dosing regimens in the pediatric population. Show less
In the development of drugs for the treatment of central nervous system (CNS) disorders, the prediction of human CNS drug action is a big challenge. Direct measurement of brain extracellular fluid ... Show moreIn the development of drugs for the treatment of central nervous system (CNS) disorders, the prediction of human CNS drug action is a big challenge. Direct measurement of brain extracellular fluid (brainECF) concentrations is highly restricted in human. Therefore, unbound drug concentrations in human cerebrospinal fluid (CSF) are used as a surrogate for human brainECF concentrations. Due to qualitative and quantitative differences in processes that govern the pharmacokinetics (PK) of drugs in the brain, a generally applicable relationship between CSF concentrations and brainECF concentrations does not exist. The aim of the research presented in this thesis was to develop a preclinical brain distribution model, allowing the prediction of human brain target site concentrations on the basis of preclinical data. In order to be able to build a brain distribution model understanding of time-dependent (also non-steady state) kinetics of the unbound drug in brainECF and CSF is essential. To that end, systematic studies on the inter-relationship of plasma PK, blood-brain barrier (BBB) transport, blood-CSF barrier (BCSFB) transport and intra-brain distribution were performed in the rat by implantation of microdialysis probes at multiple brain sites in individual animals. Show less
The endocannabinoid system has only been discovered during the last few decades, and scientific progress in understanding the relevance of this system in health and disease has been limited and... Show moreThe endocannabinoid system has only been discovered during the last few decades, and scientific progress in understanding the relevance of this system in health and disease has been limited and slow. CB1 antagonists were considered a __miracle drug__ for the treatment of obesity and smoking with __blockbuster__ potential. But due to central side effects (such as depression and suicidal behaviour) and a lack of systematic clinical pharmacologic research, market access of a CB1 antagonists failed. In this thesis, we explored some improvements in the early development of cannabinoids, and by systematically investigating, we found that the new cannabinoid antagonist TN38837 seems effective with a reduced propensity for central side effects, and that a new oral THC formulation enhances the pharmacological activities by its seemingly superior pharmacokinetics. Also, we experiment with new methodology to optimise effect measurement, including resting state-FMRI which we found suitable for early phase cannabinoid research, and including new concentration-effect models to improve the simulation and prediction of future studies. The research in this thesis shows that a revival of research on the cannabinoid system requires novel approaches to the administration of cannabinoids, to the measurements and the study designs, and to the analyses of the effects. This reflects the complexity of the highly integrated endocannabinoid system, but also sets the stage for other innovative drug development programs Show less
This book focuses on novel approach to characterize developmental changes in pharmacokinetics across human lifespan with the up-to-date Nonlinear Mixed Effect Modeling techniques.
Yassen, A.; Passier, P.; Furuichi, Y.; Dahan, A. 2013
For most commonly used drugs in morbidly obese patients evidence based dosing guidelines are not available. Therefore, current dosing is based on experience of the prescriber rather than on... Show moreFor most commonly used drugs in morbidly obese patients evidence based dosing guidelines are not available. Therefore, current dosing is based on experience of the prescriber rather than on clinical evidence. Pharmacokinetic and pharmacodynamics data in non-obese patients are extrapolated without proper exploration of influence of overweight on the dose-exposure-effect relationship. The research described in this thesis focused on two commonly used drugs, propofol and the low-molecular-weight heparin (LMWH) nadroparin with the aim to develop weight appropriate dosing algorithms for these drugs in morbidly obese patients based on population pharmacokinetic and pharmacodynamics analysis. A non-linear relationship was found between propofol clearance and total body weight in both morbidly obese and non-obese adults, adolescents and children. Furthermore, the influence of age on propofol clearance was described using a bilinear function. A model based dosing algorithm using an adjusted dosing weight for propofol maintenance infusion was successfully evaluated in a prospective study in morbidly obese adults and can therefore be implemented in daily practice. For nadroparin in both morbidly obese and non-obese patients, total body clearance increased linearly with total body weight whereas the central of volume distribution increased linearly with lean body weight, suggesting that lean body weight is clinically useful for nadroparin dosing. The developed pharmacodynamic model for nadroparin in non-obese and morbidly obese patients can be used as a starting point to further identify the appropriate anti-Xa targets in morbidly obese patients. Show less
Hoch, M.; Hay, J.L.; Hoever, P.; Kam, M.L. de; Beek, E.T. te; Gerven, J.M.A. van; Dingemanse, J. 2013
