The quantification of growth hormone secretion : application of model-informed drug development in acromegaly

Growth hormone profiles are pulsatile and highly variable between individuals, limiting the implementation of mathematical models to quantify an individual's secretion.In this thesis, five key topics regarding the quantification of growth hormone (GH) in literature and the application in (future) clinical trials were addressed consecutively:1. The current standards in reporting clinical trial outcomes in acromegaly patients were assessed and recommendations for future reporting were provided 2. A new deconvolution-informed population pharmacodynamic model wasdeveloped and validated for the quantification of drug effects on pulsatile profiles 3. Population pharmacokinetic/pharmacodynamic models were developed to better understand the clinical pharmacological properties of BIM23B065 to support decision making and future clinical trial design 4. A population model for GH secretion based on physiological information,including a GHRH pulse generator, was developed based on data from differentexperiments to be used for the simulation of pulsatile GH profiles in healthy controls, active acromegaly patients and acromegaly patient after surgery. 5. The impact of different sampling protocols, ranging from a single sample to a 24h GH profile, on the study power and classification of responders in GH research were quantified and implementation of the research methodology in new scenarios was stimulated.Pharmacolog

Predictive performance of parent-metabolite population pharmacokinetic models of (S)-ketamine in healthy volunteers

Purpose The recent repurposing of ketamine as treatment for pain and depression has increased the need for accurate population pharmacokinetic (PK) models to inform the design of new clinical trials. Therefore, the objectives of this study were to externally validate available PK models on (S)-(nor)ketamine concentrations with in-house data and to improve the best performing model when necessary. Methods Based on predefined criteria, five models were selected from literature. Data of two previously performed clinical trials on (S)-ketamine administration in healthy volunteers were available for validation. The predictive performances of the selected models were compared through visual predictive checks (VPCs) and calculation of the (root) mean (square) prediction errors (ME and RMSE). The available data was used to adapt the best performing model through alterations to the model structure and re-estimation of inter-individual variability (IIV). Results The model developed by Fanta et al. (Eur J Clin Pharmacol 71:441-447, 2015) performed best at predicting the (S)-ketamine concentration over time, but failed to capture the (S)-norketamine C-max correctly. Other models with similar population demographics and study designs had estimated relatively small distribution volumes of (S)-ketamine and thus overpredicted concentrations after start of infusion, most likely due to the influence of circulatory dynamics and sampling methodology. Model predictions were improved through a reduction in complexity of the (S)-(nor)ketamine model and re-estimation of IIV. Conclusion The modified model resulted in accurate predictions of both (S)-ketamine and (S)-norketamine and thereby provides a solid foundation for future simulation studies of (S)-(nor)ketamine PK in healthy volunteers after (S)-ketamine infusion.Stress-related psychiatric disorders across the life spa

Accelerating vaccine trial conduct in a pandemic with a hot spot-based inclusion strategy using trial and epidemic simulation

Clinical development of vaccines in a pandemic situation should be rigorous but expedited to tackle the pandemic threat as fast as possible. We explored the effects of a novel vaccine trial strategy that actively identifies and enrolls subjects in local areas with high infection rates. In addition, we assessed the practical requirements needed for such a strategy. Clinical trial simulations were used to assess the effects of utilizing these so-called "hot spot strategy" compared to a traditional vaccine field trial. We used preset parameters of a pandemic outbreak and incorporated realistic aspects of conducting a trial in a pandemic setting. Our simulations demonstrated that incorporating a hot spot strategy shortened the duration of the vaccine trial considerably, even if only one hot spot was identified during the clinical trial. The active hot spot strategy described in this paper has clear advantages compared to a "wait-and-see" approach that is used in traditional vaccine efficacy trials. Completion of a clinical trial can be expedited by adapting to resurgences and outbreaks that will occur in a population during a pandemic. However, this approach requires a speed of response that is unusual for a traditional phase III clinical trial. Therefore, several recommendations are made to help accomplish rapid clinical trial setup in areas identified as local outbreaks. The described model and hot spot vaccination strategy can be adjusted to disease-specific transmission characteristics and could therefore be applied to any future pandemic threat

Dose escalations in phase I studies: feasibility of interpreting blinded pharmacodynamic data

Aims During phase I study conduct, blinded data are reviewed to predict the safety of increasing the dose level. The aim of the present study was to describe the probability that effects are observed in blinded evaluations of data in a simulated phase I study design. Methods An application was created to simulate blinded pharmacological response curves over time for 6 common safety/efficacy measurements in phase I studies for 1 or 2 cohorts (6 active, 2 placebo per cohort). Effect sizes between 0 and 3 between-measurement standard deviations (SDs) were simulated. Each set of simulated graphs contained the individual response and mean +/- SD over time. Reviewers (n = 34) reviewed a median of 100 simulated datasets and indicated whether an effect was present. Results Increasing effect sizes resulted in a higher chance of the effect being identified by the blinded reviewer. On average, 6% of effect sizes of 0.5 between-measurement SD were correctly identified, increasing to 72% in 3.0 between-measurement SD effect sizes. In contrast, on average 92-95% of simulations with no effect were correctly identified, with little effect of between-measurement variability in single cohort simulations. Adding a dataset of a second cohort at half the simulated dose did not appear to improve the interpretation. Conclusion Our analysis showed that effect sizes <2x the between-measurement SD of the investigated outcome frequently go unnoticed by blinded reviewers, indicating that the weight given to these blinded analyses in current phase I practice is inappropriate and should be re-evaluated.PharmacologyBiopharmaceutic

Population pharmacokinetics of clonazepam in saliva and plasma: steps towards noninvasive pharmacokinetic studies in vulnerable populations

Aim Traditional studies focusing on the relationship between pharmacokinetics (PK) and pharmacodynamics necessitate blood draws, which are too invasive for children or other vulnerable populations. A potential solution is to use noninvasive sampling matrices, such as saliva. The aim of this study was to develop a population PK model describing the relationship between plasma and saliva clonazepam kinetics and assess whether the model can be used to determine trough plasma concentrations based on saliva samples. Methods Twenty healthy subjects, aged 18-30, were recruited and administered 0.5 or 1 mg of clonazepam solution. Paired plasma and saliva samples were obtained until 48 hours post-dose. A population pharmacokinetic model was developed describing the PK of clonazepam in plasma and the relationship between plasma and saliva concentrations. Bayesian maximum a posteriori optimization was applied to estimate the predictive accuracy of the model. Results A two-compartment distribution model best characterized clonazepam plasma kinetics with a mixture component on the absorption rate constants. Oral administration of the clonazepam solution caused contamination of the saliva compartment during the first 4 hours post-dose, after which the concentrations were driven by the plasma concentrations. Simulations demonstrated that the lower and upper limits of agreements between true and predicted plasma concentrations were -28% to 36% with one saliva sample. Increasing the number of saliva samples improved these limits to -18% to 17%. Conclusion The developed model described the salivary and plasma kinetics of clonazepam, and could predict steady-state trough plasma concentrations based on saliva concentrations with acceptable accuracy.Genetics of disease, diagnosis and treatmen

Biperiden challenge model in healthy elderly as proof-of-pharmacology tool: a randomized, placebo-controlled trial

Selective M-1 muscarinic acetylcholine receptor (mAChR) agonists are being developed as symptomatic treatment for neurodegenerative and neuropsychiatric disorders that lead to cognitive dysfunction. Demonstrating cognition-enhancing effects in early-phase clinical development in healthy subjects is difficult. A challenge with the M-1 mAChR antagonist biperiden could be used to demonstrate procognitive and pharmacological effects of selective M-1 mAChR agonists. The aim of this study was to develop such a model. To this end, 12 healthy elderly subjects participated in a randomized, placebo-controlled, 3-way crossover study investigating tolerability, pharmacokinetic (PK) and pharmacodynamic (PD) effects of 2 and 4 mg biperiden. Repeated PD assessments were performed using neurocognitive tasks and electrophysiological measurements. A population PK-PD model was developed. Four milligrams of biperiden showed significant impairment of sustained attention (-2.1 percentage point in adaptive tracking [95%CI, -3.043 to -1.148], verbal memory (2-3 fewer words recalled [95%CI, -5.9 to -0.2]) and working memory (up to a 50-millisecond increase in the n-back task reaction time [95%CI, 21.854-77.882]) compared with placebo. The PK data were best fitted by a 2-compartment model and showed high interoccasion and intersubject variability. Population PK-PD analysis quantified significant concentration-effect relationships for the n-back reaction time, n-back accuracy, and adaptive tracking. In conclusion, biperiden caused M-1 mAChR-related dose- and concentration-dependent temporary declines in cognitive functioning. Therefore a biperiden pharmacological challenge model can be used for proof-of-pharmacology studies and to demonstrate cognition-enhancing effects of new cholinergic compounds that are being developed.Perioperative Medicine: Efficacy, Safety and Outcome (Anesthesiology/Intensive Care

An exploratory first-in-man study to investigate the pharmacokinetics and safety of liposomal dexamethasone at a 2- and 1-week interval in patients with metastatic castration resistant prostate cancer

Dexamethasone has antitumor activity in metastatic castration resistant prostate cancer (mCRPC). We aimed to investigate intravenous liposome-encapsulated dexamethasone disodium phosphate (liposomal dexamethasone) administration in mCRPC patients. In this exploratory first-in-man study, patients in part A received a starting dose of 10 mg followed by five doses of 20 mg liposomal dexamethasone at 2-week intervals. Upon review of part A safety, patients in part B received 10 weekly doses of 18.5 mg. Primary outcomes were safety and pharmacokinetic profile, secondary outcome was antitumor efficacy. Nine mCRPC patients (5 part A, 4 part B) were enrolled. All patients experienced grade 1-2 toxicity, one (part B) patient experienced grade 3 toxicity (permanent bladder catheter-related urosepsis). No infusion-related adverse events occurred. One patient had upsloping glucose levels 50% PSA biochemical response was observed. Bi- and once weekly administrations of IV liposomal dexamethasone were well-tolerated. Weekly dosing enabled trough concentrations of liposomal- and free dexamethasone >LLOQ. The data presented support further clinical investigation in well-powered studies. Clinical trial registration: ISRCTN 10011715.Prostatic carcinom

Toma de decisiones para el uso de herramientas de gestión comercial en la empresa agrícola del Sur de Santa Fe

La comercialización de granos ocupa un lugar cada vez más relevante en la gestión de la empresa agropecuaria, sin embargo se observan falencias en la toma de decisiones comerciales de parte del productor agropecuario.. La forma de brindar información y la falta de conocimiento del funcionamiento de las herramientas de comercialización, podrían ser barreras para alcanzar competitividad en el último eslabón de la cadena productiva, la comercialización de granos.. El objetivo principal e esta investigación es identificar los aspectos que actúan como barreras limitantes en el proceso de toma de decisiones, para la adopción de herramientas de gestión comercial, de parte del productor agrícola del sur de Santa Fe.. Los objetivos específicos son conocer la percepción del productor en su rol de decisor comercial, relevar su predisposición a aprender, capacitarse y usar herramientas de gestión comercial, e identificar qué aspectos de la toma de cesiciones se deben a información escasa e inapropiada.. Las entrevistas en profundidad y reuniones de focus group, bajo el formato de talleres, fueron las herramientas utilizadas para identificar aspectos del proceso de toma de decisiones comerciales.. La investigación determina falencias en la percepción del rol del productor agrícola como decisor comercial, donde la predominancia del Locus de Control Externo y la miopía en la percepción de riesgo precio actúan como principales sesgos cognitivos, limitando la adopción de herramientas de comercialización de parte del productor agrícola del sur de Santa Fe.. La percepción de la comercialización de granos como un área compleja, la preferencia por lo simple, y la predominancia del Locus de Control Externo, afecta negativamente la predisposición a desarrollar la gestión comercial de sus empresas.. Hay un espacio de trabajo a desarrollar en la enseñanza de principios vinculados a un Locus de Control Interno, fortaleciendo conceptos al productor agrícola en su rol como decisor comercial

Variabiliteit in farmacokinetiek van intraveneuze paracetamol bij gezonde ouderen

BACKGROUND and OBJECTIVE Paracetamol is the most used analgesic in older people. The physiological changes occurring with ageing influence the pharmacokinetics of paracetamol and its variability. A population pharmacokinetic analysis to describe the pharmacokinetics of intravenous paracetamol in fit older people was performed. Thereafter, simulations were conducted to illustrate target attainment and variability of paracetamol exposure following current dosing regimens (1000 mg q6h, q8h) using steady-state concentration (Css-mean) of 10 mg/L as target for effective analgesia. DESIGN and METHODS A population pharmacokinetic-analysis, using NONMEM 7.2, was performed based on 601 concentrations of paracetamol from 30 fi

Comprehensive evaluation of microneedle-based intradermal adalimumab delivery vs. subcutaneous administration: results of a randomized controlled clinical trial

Aims To evaluate feasibility of intradermal (i.d.) adalimumab administration using hollow microneedles, and to compare a single i.d. dose of adalimumab using a hollow microneedle with a single subcutaneous (s.c.) dose using a conventional needle.Methods In this single-centre double-blind, placebo-controlled, double-dummy clinical trial in 24 healthy adults we compared 40 mg adalimumab (0.4 mL) administered i.d. using a hollow microneedle with a s.c. dose using a conventional needle. Primary parameters were pain, acceptability and local tolerability; secondary parameters safety, pharmacokinetics and immunogenicity. We explored usability of optical coherence tomography, clinical photography, thermal imaging, and laser speckle contrast imaging to evaluate skin reaction after i.d. injections. In vitro protein analysis was performed to assess compatibility of adalimumab with the hollow microneedle device.Results While feasible and safe, injection pain of i.d. adalimumab was higher compared to s.c. adalimumab (35.4 vs. 7.9 on a 100-point visual analogue scale). Initial absorption rate and relative bioavailability were higher after i.d. adalimumab (time to maximum plasma concentration = 95 h [47-120]; F-rel = 129% [6.46%]) compared to s.c. adalimumab (time to maximum plasma concentration = 120 h [96-221]). Anti-adalimumab antibodies were detected in 50% and 83% of the subjects after i.d. and s.c. adalimumab, respectively. We observed statistically significantly more erythema and skin perfusion after i.d. adalimumab, compared to s.c. adalimumab and placebo injections (P < .0001). Cytokine secretion after whole blood lipopolysaccharide challenge was comparable between administration routes.Conclusions Intradermal injection of adalimumab using hollowing microneedles was perceived as more painful and less accepted than s.c. administration, but yields a higher relative bioavailability with similar safety and pharmacodynamic effects.Biological, physical and clinical aspects of cancer treatment with ionising radiatio