Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Dominika Sobotová Tutor: PharmDr. Ivan Vokřál, Ph.D. Title of diploma thesis: Pharmacokinetics of ivermectin in the sheep feces Key words: ivermectin, pharmacokinetics, sheep, anthelminthic Infection with internal parasites (endoparasites) is one of the most common diseases in sheep. Infection with these parasites mainly with the barber's pole worm (Haemonchus contortus) causes considerable economic losses and has a significant impact on sheep productivity. Anthelmintics, including ivermectin, are used for treatment. Ivermectin belongs to the class of macrocyclic lactones and is characterised by broad spectrum and low toxicity. On the other hand, it poses a risk to the environment in form of residues that are excreted in feces by treated individuals. The aim of this study was to determine the excretion profile of ivermectin in sheep subcutaneously administered in a standard dose 0,2 mg/kg of body weight. UHPLC/MS/MS method was used for the analysis of ivermectin fecal concentration. Based on the obtained results we determined basic pharmacokinetic parameters which includes time to achieve maximum concentration (tmax), maximum concentration (cmax), area under the curve (AUC) and mean residence...

A dissertation submitted to the Faculty of Medicine in part fulfilment of the requirements for the Degree of Master of Medicine in Psychiatry at the University of the Witwatersrand. Johannesburg / This dissertation consists of a review of the literature, past and present, pertaining to the metal lithium. An overview is presented of its actions, its adverse effects, and its use in medicine particularly in psychiatry. As it is not irregular for many patients to receive two or more drugs concomitantly and often in a combination which has the potential to interact adversely, an overview of these interactions is also presented. / IT2018

Introdução: pacientes com epilepsia em tratamento com politerapia podem manifestar sinais de efeitos adversos e/ou ineficácia terapêutica decorrentes das possíveis interações entre as diferentes drogas antiepilépticas (DAEs) que compõem o esquema terapêutico. Para contornar esta situação, as DAEs desenvolvidas atualmente apresentam perfil farmacocinético com menor potencial para interações farmacológicas. O levetiracetam é uma nova DAE aprovada para utilização como terapia adjuntiva no tratamento de crises focais em adultos. Seu metabolismo, por não depender de forma significativa do sistema oxidativo microssomal hepático, proporciona associações positivas com outras DAEs. Entretanto, observações clínicas de que a associação entre levetiracetam e DAEs indutoras enzimáticas (carbamazepina, fenitoína, fenobarbital e primidona) implicaria em menor disposição plasmática do levetiracetam têm sido confirmadas por alguns estudos e consideradas irrelevantes por outros. Objetivo: caracterizar e comparar o perfil farmacocinético do levetiracetam entre pacientes adultos com epilepsia em tratamento regular com DAEs indutoras enzimáticas e pacientes que estejam ou em tratamento com DAEs que não alteram a atividade das enzimas de metabolismo ou sem tratamento farmacológico. Casuística e Métodos: trinta pacientes foram selecionados, tendo sido alocados quinze em cada grupo, de acordo com o perfil das DAEs em uso regular (grupo indutor enzimático e grupo controle). A todos foi administrada dose única oral de levetiracetam 1000 mg. Ao longo de 24 horas foram coletadas sete amostras de sangue para determinação da concentração plasmática do levetiracetam e três amostras de urina para quantificação do levetiracetam eliminado inalterado e de seu principal metabólito inativo, o ucb L057. As amostras foram encaminhadas à Universidade de Pavia, Itália, e analisadas por cromatografia líquida de alta eficiência (HPLC). Resultados: foram calculados os seguintes parâmetros farmacocinéticos: concentração plasmática máxima de levetiracetam e o tempo decorrido até seu alcance; meia-vida de eliminação; constante de velocidade de eliminação; área sob a curva de concentração plasmática versus tempo; clearance oral aparente e clearance renal do levetiracetam; volume aparente de distribuição e quantidades excretadas na urina como fármaco inalterado e como ucb L057. Comparações entre os grupos foram feitas a partir dos testes t de Student ou Mann-Whitney, conforme apropriado. O grupo em tratamento com DAEs indutoras enzimáticas apresentou clearance oral aparente do levetiracetam significativamente maior e meia-vida de eliminação significativamente menor do que o grupo controle (p < 0,05). As quantidades tanto de levetiracetam quanto de ucb L057 eliminadas na urina não divergiram significativamente entre os dois grupos (p > 0,05). Discussão e Conclusões: estudos têm evidenciado o potencial das DAEs indutoras enzimáticas tanto para estimular a atividade de enzimas hidrolíticas, como as responsáveis pela conversão do levetiracetam a ucb L057, quanto para inibir e/ou competir pelos sítios de ligação dos transportadores presentes nos túbulos renais responsáveis pela secreção ativa do ucb L057. Embora o presente estudo não tenha objetivado identificar e caracterizar as vias de metabolismo e eliminação do levetiracetam, os dados encontrados evidenciam a diferença na disposição plasmática deste fármaco quando associado às DAEs indutoras enzimáticas. Considerando que o levetiracetam é majoritariamente prescrito em associações, as quais geralmente envolvem ao menos uma DAE indutora enzimática, o sucesso da terapêutica dos pacientes em que o levetiracetam for adicionado ao esquema medicamentoso prévio ou em que as DAEs indutoras enzimáticas tenham suas posologias modificadas pode ser prejudicado caso não haja o reconhecimento da possibilidade de ocorrência da alteração de perfil farmacocinético evidenciada. / Introduction: patients with epilepsy treated with two or more antiepileptic drugs (AEDs) associated (politherapy) can show signs of adverse effects and/or therapeutic inefficacy due to possible interactions among the different combined AEDs. As an attempt to handle this problem, the AEDs developed nowadays are showing pharmacokinetic characteristics that decrease their potential to get involved in pharmacological interactions. Levetiracetam is a new AED approved as add-on therapy for the treatment of focal seizures in adults. Its metabolism does not rely significantly on the hepatic microssomal oxidative system, what has been considered a positive aspect in favor of its use in association with other AEDs. However, clinical observations of decreased levetiracetam plasma disposition when it is associated with enzyme inducing AEDs (carbamazepine, phenytoin, phenobarbital and/or primidone) has been confirmed by some studies and considered irrelevant by others. Purpose: to describe and compare the pharmacokinetic profile of levetiracetam among adult patients with epilepsy in treatment with enzyme-inducers AEDs and patients in treatment with AEDs without any impact on enzymes activity or with no pharmacological treatment. Patients and Methods: a single oral dose of levetiracetam 1000 mg was administered for the thirty selected patients (fifteen per group). Over 24 hours, seven blood samples were collected to have their levetiracetam concentrations quantified, and three urine samples were collected to have their levetiracetam and ucb L057 (the main levetiracetam inactive metabolite) amounts quantified. The samples were sent to University of Pavia, Italy, to be analyzed by high performance liquid chromatography (HPLC). Results: the following pharmacokinetics parameters were calculated: the maximum plasma levetiracetam concentration and the time it occurred, elimination half-life, elimination rate constant, area under the curve, levetiracetam apparent oral clearance and renal clearance, volume of distribution and amount excreted in urine as unchanged drug and as ucb L057. Comparisons between the two groups were performed by Student t-test or Mann-Whitney test, as appropriate. The group of patients treated with enzyme-inducers AEDs showed the levetiracetam apparent oral clearance significantly higher and elimination half-life significantly lower than those from control group (p < 0,05). The amount excreted in urine as unchanged drug and as ucb L057 were not significantly different between the two groups (p > 0,05). Discussion: some studies highlight the capacity of enzyme inducing AEDs both to increase the activity of hydrolysis enzymes, such as those responsible for converting levetiracetam to ucb L057, and to inhibit and/or to compete for the binding sites on the transporters responsible for active tubular secretion of ucb L057. Although the present study did not aim to identify and describe the metabolic and elimination pathways of levetiracetam, the data found clearly show the difference in levetiracetam disposition when it is associated with enzyme inducing AEDs. Considering that levetiracetam is mainly prescribed in association with other drugs, and in most of these associations at least one drug is an enzyme inducer, neglecting this evident change in levetiracetam pharmacokinetic in cases such as those which levetiracetam is added to a previous regimen, or those which enzyme-inducers have their prescription changed, can negatively affect the success of the treatment and consequently the patients quality of life.

by Patricia Jane Anderson. / Thesis (M. Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 199-215). / List of Figures --- p.i / List of Tables --- p.v / List of Abbreviations --- p.viii / Abstract --- p.1 / Introduction --- p.3 / Chapter Chapter 1 - --- Literature Reviews / Chapter 1.1 --- Pharmacoanthropology and Pharmacogenetics --- p.5 / Chapter 1.1.1 --- Genetic Polymorphisms --- p.7 / Chapter 1.1.2 --- Pharmacogenetics in Asians and Caucasians --- p.13 / Chapter 1.1.2.1 --- ACE-inhibitors in Asians and Caucasians --- p.18 / Chapter 1.2 --- The Renin Angiotensin System --- p.20 / Chapter 1.2.1 --- Discovery of Inhibitors of Angiotensin Converting Enzyme --- p.24 / Chapter 1.3 --- ACE-Inhibiting Drugs --- p.25 / Chapter 1.3.1 --- Pharmacokinetics and Pharmacodynamics of Perindopril --- p.28 / Chapter 1.3.2 --- The Pharmacokinetics and Pharmacodynamics of Cilazapril --- p.32 / Chapter Chapter 2 - --- General Methodology / Chapter 2.1 --- Introduction --- p.38 / Chapter 2.2 --- Subjects --- p.49 / Chapter 2.3 --- Sample Collection --- p.40 / Chapter 2.3.1 --- Blood Samples --- p.40 / Chapter 2.3.2 --- Urine Samples --- p.40 / Chapter 2.4 --- Blood Pressure and Heart Rate Measurements --- p.41 / Chapter 2.5 --- Measurement of Transthoracic Electrical Bioimpedance --- p.41 / Chapter 2.5.1 --- Background --- p.42 / Chapter 2.5.2 --- Practical Details --- p.45 / Chapter 2.6 --- Data Analysis --- p.48 / Chapter 2.6.1. --- Analysis of Pharmacokinetic Parameters --- p.48 / Chapter 2.6.2 --- Analysis of Pharmacodynamic Parameters --- p.59 / Chapter 2.6.3 --- Analysis of Non-Invasive Haemodynamic Monitoring Data --- p.60 / Chapter 2.7 --- Statistical Analysis --- p.64 / Chapter Chapter 3 - --- The Perindopril Study / Chapter 3.1 --- Introduction --- p.67 / Chapter 3.1.1 --- Aims --- p.67 / Chapter 3.2 --- Methodology --- p.68 / Chapter 3.2.1 --- Inclusion Criteria --- p.68 / Chapter 3.2.2 --- Non-Inclusion Criteria --- p.69 / Chapter 3.2.3 --- Study Design --- p.69 / Chapter 3.2.4 --- Blood Sampling --- p.71 / Chapter 3.2.5 --- Urine Sampling --- p.71 / Chapter 3.2.6 --- Blood Pressure and Heart Rate --- p.72 / Chapter 3.2.7 --- Non-invasive Haemodynamic Monitoring --- p.72 / Chapter 3.2.8 --- Analysis of Plasma Samples --- p.73 / Chapter 3.2.9 --- Hormone and Enzyme Assays --- p.74 / Chapter 3.3 --- Data Analysis and Statistical Methods --- p.75 / Chapter 3.3.1 --- Pharmacokinetic Analysis of Plasma --- p.75 / Chapter 3.3.2 --- Pharmacokinetic Analysis of Urine --- p.75 / Chapter 3.3.3 --- Pharmacodynamic Analysis of Hormone Data --- p.75 / Chapter 3.3.4 --- Analysis of Haemodynamic Monitoring Data --- p.76 / Chapter 3.3.5 --- Statistical Analysis --- p.76 / Chapter 3.4 --- Pharmacokinetic Results --- p.77 / Chapter 3.4.1 --- Pharmacokinetics of Perindopril in Plasma --- p.77 / Chapter 3.4.2 --- Pharmacokinetics of Perindopril in Urine --- p.84 / Chapter 3.4.3. --- Pharmacokinetics of Perindoprilat in Plasma --- p.85 / Chapter 3.4.4 --- Pharmacokinetics of Perindoprilat in Urine --- p.89 / Chapter 3.5 --- Pharmacodynamic Results --- p.89 / Chapter 3.5.1 --- Angiotensin Converting Enzyme Inhibition --- p.89 / Chapter 3.5.2 --- Angiotensin I (AI) --- p.102 / Chapter 3.5.3 --- Aldosterone and Plasma Renin Activity (PRA) --- p.102 / Chapter 3.5.4 --- Plasma Protein Binding --- p.102 / Chapter 3.5.5 --- Blood Pressure and Heart Rate --- p.107 / Chapter 3.5.6. --- Safety and Tolerance --- p.108 / Chapter 3.5.7 --- Non-invasive Haemodynamic Monitoring --- p.108 / Chapter 3.6 --- Discussion --- p.120 / Chapter Chapter 4 - --- The Cilazapril Study / Chapter 4.1 --- Introduction --- p.135 / Chapter 4.1.1 --- Aims --- p.135 / Chapter 4.2 --- Methodology --- p.136 / Chapter 4.2.1 --- Inclusion Criteria --- p.136 / Chapter 4.2.2. --- Exclusion Criteria --- p.136 / Chapter 4.2.3 --- Study Design --- p.137 / Chapter 4.2.4 --- Blood Sampling --- p.139 / Chapter 4.2.5 --- Urine Sampling --- p.140 / Chapter 4.2.6 --- Blood Pressure and Heart Rate --- p.140 / Chapter 4.2.7 --- Non-Invasive Haemodynamic Monitoring --- p.140 / Chapter 4.2.8 --- Analysis of Plasma Cilazaprilat Samples --- p.142 / Chapter 4.2.9 --- Hormone and Enzyme Assays --- p.143 / Chapter 4.3 --- Data Analysis and Statistical Methods --- p.143 / Chapter 4.3.1 --- Pharmacokinetic Analysis --- p.143 / Chapter 4.3.2 --- Pharmacodynamic Analysis of Hormone Data --- p.144 / Chapter 4.3.3 --- Analysis of Non-Invasive Haemodynamic Monitoring Data --- p.144 / Chapter 4.3.4 --- Statistical Analysis --- p.146 / Chapter 4.4 --- Pharmacokinetic Results --- p.146 / Chapter 4.4.1 --- Pharmacokinetics of Cilazaprilat in Plasma --- p.146 / Chapter 4.5 --- Pharmacodynamic Results --- p.150 / Chapter 4.5.1 --- Angiotensin Converting Enzyme Inhibition --- p.150 / Chapter 4.5.2 --- Aldosterone and Plasma Renin Activity (PRA) --- p.155 / Chapter 4.5.3 --- Blood Pressure and Heart Rate --- p.155 / Chapter 4.5.4 --- Safety and Tolerance --- p.159 / Chapter 4.5.5 --- Non-Invasive Haemodynamic Monitoring --- p.160 / Chapter 4.6 --- Discussion --- p.182 / Chapter Chapter 5 - --- General Discussion --- p.188 / Appendix --- p.195 / References --- p.199 / Acknowledgements --- p.216

Tse Kai Kong. / Thesis submitted in: August 1998. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 116-122). / Abstract also in Chinese. / ABSTRACT --- p.ii / 摘要 --- p.v / ACKNOWLEDGEMENTS --- p.viii / CONTENTS --- p.ix / LIST OF FIGURES --- p.xiii / LIST OF TABLES --- p.xvii / ABBREVIATIONS --- p.xix / Chapter CHAPTER ONE --- Introduction --- p.1 / Chapter 1 --- Introduction --- p.2 / Chapter 1.1 --- Definition and Prevalence of Epilepsy --- p.2 / Chapter 1.2 --- Neurophysiology and Pathophysiology of Epilepsy --- p.3 / Chapter 1.3 --- Drugs Currently Used in the Treatment of Epilepsy --- p.5 / Chapter 1.4 --- Triazolines Aminoalkylpyridines as a New Class of Potential Antiepileptic Drugs --- p.9 / Chapter 1.5 --- Chemical Synthesis of Aminoalkylpyridines --- p.14 / Chapter 1.6 --- Metabolism of Aminoalkylpyridines --- p.15 / Chapter 1.7 --- Anticonvulsant Activities of Aminoalkylpyridines --- p.16 / Chapter 1.8 --- Aim and Scope of the Present Study --- p.18 / Chapter CHAPTER TWO --- Experimental --- p.19 / Chapter 2.1 --- MATERIALS --- p.20 / Chapter 2.2 --- PREFORMULATION STUDIES ON AMINOALKYLPYRIDINES --- p.22 / Chapter 2.2.1 --- Determination of Partition Coefficient --- p.22 / Chapter 2.2.2 --- Determination of Aqueous Solubilities --- p.22 / Chapter 2.2.3 --- Determination of Thermal Properties --- p.23 / Chapter 2.3 --- DEVELOPMENT OF A HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC ASSAY FORp-C1 AMINOALKYLPYRIDINES --- p.24 / Chapter 2.3.1 --- HPLC Apparatus and Conditions --- p.24 / Chapter 2.3.2 --- Animal Treatments and Biological Fluid Collection --- p.24 / Chapter 2.3.3 --- Solid Phase Extraction --- p.25 / Chapter 2.3.4 --- Construction of Calibration Curves for p-Cl AAP in Rat Blood --- p.25 / Chapter 2.3.5 --- Construction of Calibration Curves for p-Cl AAP in Rat Urine --- p.26 / Chapter 2.3.6 --- Accuracy and Precision in the Quantitation of p-C1 AAP in Biological Fluids --- p.26 / Chapter 2.4 --- PRELIMINARY PHARMACOKINETICS OF p-C1 AAP FOLLOWING INTRAVENOUS ADMINISTRATION --- p.27 / Chapter 2.4.1 --- Cannulae Preparation --- p.27 / Chapter 2.4.2 --- Dosage --- p.27 / Chapter 2.4.3 --- Animal Surgery and Sample Collection --- p.28 / Chapter 2.4.4 --- Pharmacokinetic Calculations --- p.29 / Chapter 2.5 --- URINARY METABOLIC STUDIES OF p-C1 AAP --- p.30 / Chapter 2.5.1 --- Animal Treatment and Urine Collection --- p.30 / Chapter 2.5.2 --- Deconjugation Assay --- p.30 / Chapter 2.5.3 --- Non-deconjugated Urine Sample Treatment --- p.31 / Chapter 2.5.4 --- Separation of Metabolites by HPLC --- p.31 / Chapter 2.5.5 --- Identification of Metabolites by LC/MS --- p.31 / Chapter 2.5.6 --- Quantitative Analysis --- p.32 / Chapter 2.5.7 --- Preparation of the authentic β-amino alcohol --- p.34 / Chapter 2.6 --- STATISTICAL ANALYSIS --- p.34 / Chapter CHAPTER THREE --- Results and Discussion --- p.35 / Chapter 3.1 --- PREFORMULATION STUDIES ON AMINOALKYLPYRIDINES --- p.36 / Chapter 3.1.1 --- PARTITION COEFFICIENT (K°W) --- p.36 / Chapter 3.1.2 --- AQUEOUS SOLUBILITY --- p.37 / Chapter 3.1.3 --- THERMAL ANALYSIS --- p.41 / Chapter 3.2 --- DEVELOPMENT OF A HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC ASSAY FOR p-C1 AMINOALKYLPYRIDINES --- p.49 / Chapter 3.2.1 --- SOLID PHASE EXTRACTION --- p.49 / Chapter 3.2.2 --- CONSTRUCTION OF CALIBRATION CURVES FOR p-C1 AAP IN THE RAT BLOOD --- p.49 / Chapter 3.2.3 --- CONSTRUCTION OF CALIBRATION CURVES FOR p-C1 AAP IN THE RAT URINE --- p.52 / Chapter 3.2.4 --- ACCURACY AND PRECISION IN THE QUANTITATION OF p-Cl IN THE BIOLOGICAL FLUIDS --- p.54 / Chapter 3.3 --- PRELIMINARY PHARMACOKINETICS OF p-C1 AAP FOLLOWING INTRAVENOUS ADMINISTRATION --- p.57 / Chapter 3.4 --- URINARY METABOLIC STUDIES OF p-C1AAP --- p.61 / Chapter 3.4.1 --- QUALITATIVE STUDIES : IDENTIFICATION OF METABOLITES --- p.61 / Chapter 3.4.2 --- QUANTITATIVE STUDIES --- p.94 / Chapter CHAPTER FOUR --- Conclusion --- p.111 / REFERENCES --- p.115 / APPENDIX Published Papers --- p.121

Objetivos: O objetivo deste estudo foi avaliar a influência do Diabetes Mellitus do tipo 2 na farmacocinética da glimepirida em ratos Wistar e descrever o perfil através de modelo farmacocinética populacional (popPK). Metodologia: Os experimentos com animais foram aprovados pelo CEUA/UFRGS (protocolo #27892). O diabetes foi induzido com administração intraperitoneal de 100 mg/kg de nicotinamida, 15 minutos antes da administração intravenosa de 65 mg/kg de STZ. Os animais com nível de glicemia > 250 mg/dL foram considerados diabéticos. A glimepirida foi administrada na dose de 5 mg/kg via i.v. nos animais sadios (n = 11) e diabéticos (n = 9) e quantificada por CLAE-UV. A ligação às proteínas plasmáticas foi determinada por método de ultracentrifugação (Centrifree®). A análise farmacocinética não compartimental (software Phoenix®) foi realizada, assim como a modelagem farmacocinética populacional (software Monolix ®). Resultados e Discussão: A metodologia analítica para quantificação da glimepirida em plasma foi desenvolvida e validada, seguindo os critérios do FDA, apresentou sensibilidade, exatidão e precisão. O modelo de indução da diabetes produziu glicemia > 250 mg/dL. A ligação às proteínas plasmáticas não foi afetada pela doença (LPPSaudáveis = 99,3 ± 0,09%, LPPDiabéticos = 99,13 ± 0,075%, p > 0,05). O modelo farmacocinético populacional estrutural de 2 compartimentos com eliminação de primeira-ordem com covariável categórica (diabetes), foi usado para descrever os perfis plasmáticos de concentração-tempo da glimepirida após administração intravenosa na dose de 5 mg/kg a ratos saudáveis e diabéticos. O CL e a ASC0-inf dos animais diabéticos foram estatisticamente diferentes dos animais saudáveis, CLpop Saudáveis= 0,066 L/h para CLpop diabéticos = 0,024 L/h e ASCpop saudáveis = 19,24 μg/mL.h para ASCpop diabéticos = 59,64 μg.h/mL, indicando que a eliminação foi alterada nos animais diabéticos induzidos STZ. Conclusões: A modela gempossibilitou identificação do parâmetro que atribuiu variabilidade entre os grupos. Desta forma, a variabilidade interindividual foi quantificada e incluída no modelo. O modelo popPK final, nos permitiu elucidar os fatores que afetam a farmacocinética da glimepirida e prever mudanças na exposição em uma população específica. / Objective: The aim of this study was to evaluate the influence of diabetes mellitus type 2 on the pharmacokinetics of glimepiride in rats and describe the profile in population pharmacokinetic model (popPK). Methods: The experiments with animals were approved by CEUA/UFRGS (protocol number). The diabetes was induced by intraperitoneal administration of NA (100 mg/kg) dissolved in saline 15 min before an intravenous administration of 65 mg/kg STZ in citrate buffer (pH 4.5) to overnight fasted rats. Animals with blood glucose level> 250 mg/dL were considered diabetic. After administered of glimepiride at a dose of 5 mg/kg i.v. bolus in healthy (n = 11) and diabetic animals (n = 9). Method HPLC-UV developed and validated quantified plasma concentrations. The plasma protein binding was determined by method ultracentrifugation (Centrifree®). Noncompartmental analysis of pharmacokinetic in Phoenix® software was performed, as well as the model pharmacokinetic population using Monolix®. Performed by Student's t-test for SigmaStat® software. Results and Discussion: The HPLC-UV method for quantification of glimepiride in plasma was developed and validated following requirements by FDA showing sensitivity, accuracy and precision. Induced diabetes model produced glucose> 250 mg / dL. The plasma protein binding was not affect by the disease (LPPSaudáveis = 99.3 ± 0.09%, LPPDiabéticos = 99.13 ± 0.075%, p> 0.05). The model pharmacokinetic population 2 compartments with eliminating first-order with categorical covariates diabetic was used to describe the plasma profile concentration-time glimepiride. The CL and AUC 0-inf of diabetic animals were significantly different. In healthy animals was Clpop Healthy = 0.066 L/h for diabetics Clpop = 0.024 L/h and healthy ASCpop = 19.24 g/mL.h ASCpop for diabetics = 59.64 g/mL.h, indicating that elimination was decreased in induced diabetic rats STZ. Conclusions: popPk enabled identification of the parameter assigned variability between the groups. Thus, the inter subject variability was measured and included in the model. The PBPK final model, allowed us to elucidate the factors that affect the pharmacokinetics of glimepiride and predict changes in exposure in a specific population.

The pharmacokinetics of ethanol and (-)-trans-isomer of 9-tetrahydrocannabinol (THC), and the pharmacokinetic interaction between them were characterized using statistical models in this thesis. In chapter II, a semi-mechanistic absorption rate dependent hepatic extraction model was developed to characterize ethanol pharmacokinetics. The statistical analysis conducted based on this model indicated no association between ethanol disposition and subject age or sex, and a 23% higher typical Vmax value, a 12.5% lower typical Km value for heavy drinkers compared with moderate drinkers. In chapter III, a parent-metabolite pharmacokinetic model was developed to simultaneously describe the concentration time profile of THC and its active metabolite 11-OH-THC. A parent-metabolite model with 3-compartment pharmacokinetic model for THC and a 2-compartment model for 11-OH-THC was found to best describe the pharmacokinetics of THC and 11-OH-THC simultaneously. In chapter IV, the pharmacokinetic interactions of ethanol on THC, 11-OH-THC and 11-nor-COOH-THC were evaluated using linear mixed effects models. The results suggested that co-administration of ethanol caused an increase in THC and 11-OH-THC systemic exposure, failed to influence the terminal elimination processes of THC and 11-OH-THC, and did not affect the pharmacokinetics of 11-nor-9-COOH-THC.

Pyronaridine/Artesunate (PA) 3:1 fixed dose combination is a novel artemisinin-based combination therapy (ACT) in development for the treatment of acute uncomplicated Plasmodium falciparum or Plasmodium vivax malaria. An understanding of both pharmacokinetics and pharmacodynamics of pyronaridine is of importance in order to achieve optimal therapeutic outcome. In this thesis, population pharmacokinetic models for pyronaridine in healthy subjects, and adult and pediatric malaria patients were developed. Pyronaridine pharmacokinetics in both adult and pediatric populations were best described by a two compartment model with first order absorption and elimination from the central compartment. A presence of malaria infection and body weight were the significant covariates that explained pyronaridine pharmacokinetic variability in the adult population. For the pediatric population, age was the only significant covariate that explained pyronaridine pharmacokinetic variability. Monte Carlo simulations were also performed to address differences in pyronaridine exposures among these populations and to explore the exposures of pyronaridine among recommended dosage regimens for pediatric and adult malaria patients. Healthy adults had a higher exposure to pyronaridine as compared to adult malaria patients. For the pediatric population, younger children had a higher exposure to pyronaridine as compared to older children. The overall range of pyronaridine exposures among dosing groups for adult and pediatric malaria patients were relatively similar. The cut-off values of pyronaridine pharmacokinetic parameters associated with successful treatment outcome were also determined by means of receiver operating characteristic (ROC) curve. These cut-off values can be used to optimize the outcome of malaria treatment. Additionally, Cox proportional hazard model was conducted to determine the relationship between several covariates and time to the occurrence of re-infection or recrudescence. The models showed that as the levels of predicted pyronaridine concentrations on day 7 increased, the risks of acquiring re-infection or recrudescence decreased. Finally, pharmacokinetic drug-drug interaction of pyronaridine and ritonavir was assessed based on the overlap pathway for metabolism of both drugs and the high rates of HIV and malaria co-infection. There was an effect of ritonavir on pyronaridine pharmacokinetics. However, the results were not considered clinically relevant. An increase in ritonavir exposure was observed in the presence of fixed dose PA.

The aims of this thesis were to examine: (1) plasma and cellular pharmacokinetics of daunorubicin and its major metabolite daunorubicinol in patients with acute leukaemia, and the relationships between pharmacokinetics, patient response and the presence of P glycoprotein; (2) actions of the multidrug resistance reversing agents cyclosporin A and trifluoperazine, at clinically achievable concentrations, on daunorubicin accumulation and retention in human leukaemia cell lines and patients with acute leukaemia; and (3) effect of daunorubicin on the cell membrane of both sensitive and resistant cell lines, with and without the multidrug resistance reversing agents. Twenty-seven patients with acute leukaemia received daunorubicin as part of induction therapy. The plasma and cellular levels of daunorubicin and its metabolite daunorubicinol were determined using HPLC. There were no significant differences between patients who went into complete remission (12 out of 23) compared to those who did not respond for any of the plasma pharmacokinetic parameters. There was a significant difference in the cellular daunorubicin and daunorubicinol area under the concentration-time curve between responders and non responders (p less than 0.02), as well as in cellular Cmax, cellular clearance and cellular volume of distribution. Eleven patients were P glycoprotein positive and 10 P glycoprotein negative (no sample available for 2 patients). There was no correlation between patient response and the presence of P glycoprotein; nor a correlation between the cellular concentration of daunorubicin or daunorubicinol and P glycoprotein. Patients responding to chemotherapy had higher cellular daunorubicin and daunorubicinol compared to non responders. In contrast to in vitro studies, overexpression of P glycoprotein was not the reason for the lower cellular daunorubicin levels. Cyclosporin A was capable of increasing both cellular accumulation and retention in the drug resistant CEM/VLB and HL 60/ADR cell lines, but not in the drug sensitive CEM and HL 60 cell lines. Trifluoperazine had no effect in any of the four cell lines. In contrast to the cell line findings, only the combination of cyclosporin A and trifluoperazine were able to increase both accumulation and retention in the blast cells of patients at initial presentation. The multidrug resistant reversing agents alone had no effect in increasing accumulation or retention in the blast cells of P glycoprotein positive patients, nor patients in relapse. The cell line studies show that at clinically relevant concentrations only cyclosporin A is capable of increasing daunorubicin accumulation in both the drug resistant P glycoprotein positive (VLB) and P glycoprotein negative (ADR) cell lines. Thus, cyclosporin A does not work only by inhibiting the actions of P glycoprotein. Trifluoperazine was unable to reverse drug resistance at clinically relevant concentrations in either cell lines or patient blast cells. However, the combination of cyclosporin A and trifluoperazine increased accumulation in patient blast cells at initial presentation, suggesting that these agents may be more useful in patients at initial presentation than relapse. Daunorubicin was immobilised by linking it to poly vinyl alcohol and the effect of immobilised-daunorubicin was studied on the four cell lines above. The immobilised-daunorubicin was able to decrease cell growth in the drug sensitive HL 60 cell line but not in the drug resistant VLB or ADR cell lines. Poly vinyl alcohol itself was cytotoxic to the CEM cell line. The multidrug resistance reversing agents cyclosporin A and trifluoperazine were only capable of increasing cytotoxicity in the HL 60 cell line, with no effect in the drug resistant VLB or ADR cell lines.

The pharmacokinetics, oral bioavailability, cerebrovascular permeability and biotransformation of the neurotoxic plasticiser n-butylbenzenesulfonamide (NBBS) were studied in order that the human health risk due to environmental exposure to NBBS could be evaluated. The pharmacokinetics of NBBS was determined in Wistar rats, following intravenous administration of the isotopomer [13C6] NBBS (1 mg/kg in 0.9% saline). [13C6] NBBS is cleared from plasma at a rate of 5 ml/min by the liver. The plasticiser has a short distribution phase (t1/2 of 47 seconds) and a long terminal phase (t1/2 of 17 hours). Plasma [13C6] NBBS concentrations, 24 hours after administration, represented 0.04% of the administered dose. These data indicated rapid uptake into tissue, which was subsequently confirmed by monitoring tissue concentrations of [13C6] NBBS for upto 8 hours following administration. [13C6] NBBS was not accumulated by any of the tissues studied (brain, liver, kidney, muscle and adipose tissue). Oral bioavailability was determined by simultaneously administering native NBBS orally and [13C6] NBBS intravenously to Wistar rats. The plasticiser was found to be absorbed erratically and subject to first pass metabolism. Plasma concentrations of orally administered NBBS fluctuated over the duration of the experiment. Furthermore, limitations posed by the assay resulted in truncated oral curves. These factors precluded estimation of areas under the oral NBBS curves to infinity and partial area ratios were instead used to calculate absolute bioavailability (mean of 19%). Cerebrovascular permeability of NBBS was determined with [13C6] NBBS, in Sprague-Dawley rats, using the in-situ brain perfusion technique of Takasato et al. (1984). The uptake of [13C6] NBBS into brain was very rapid and flow limited. Assuming an average cerebral perfusion fluid flow rate of 0.11 ml/s/g, the calculated single pass extraction value for [13C6] NBBS is 99.9% with a Kin of 0.11 ml/s/g. This is in close agreement with experimental values for the 15 second saline perfusions (extraction = 98% - 125% and Kin = 0.108 - 0.137). Differences in regional brain distribution of the plasticiser were not found. In-vitro biotransformation studies revealed one phase I metabolite in incubates of NBBS containing human, rabbit and rat post-mitochondrial supernatant (S9 fraction). This metabolite is 2-hydroxy-n-butylbenzenesulfonamide (NBBS-OH hydroxylated in the Based on these data, environmental exposure to NBBS does not pose a significant human health risk.