Investigation of surfactant-drug pharmacokinetic interactions

II UITTREKSEL . IV ACKNOWLEDGEMENTS . VI TABLE OF CONTENTS . VIII LIST OF ABBREVIATIONS . XIII LIST OF TABLES . XV LIST OF FIGURES . XX CHAPTER 1: INTRODUCTION . 1 1.1 Background . 1 1.1.1 Rhodamine 123 as model compound . 2 1.1.2 Models for evaluating drug absorption . 3 1.2 Research problem . 4 1.3 Aims and objectives . 4 1.3.1 General aim and objective . 4 1.3.2 Specific aims and objectives . 4 1.4 Ethical considerations . 5 1.5 Structure of dissertation . 5 CHAPTER 2: A LITERATURE REVIEW ON INTESTINAL DRUG ABSORPTION AND SURFACTANTS . 6 ix 2.1 Anatomy and physiology of the gastrointestinal tract . 6 2.1.1 Comparison of the gastrointestinal anatomy and physiology of humans and pigs . 7 2.1.1.1 Stomach . 8 2.1.1.2 Small intestine . 9 2.1.1.3 Large intestine . 10 2.2 Pharmacokinetics . 11 2.2.1 Absorption mechanisms in the gastrointestinal tract . 11 2.2.1.1 Transcellular pathway . 12 2.2.1.1.1 Passive diffusion . 12 2.2.1.1.2 Carrier-mediated transport . 13 2.2.1.2 Endocytosis, pinocytosis & transcytosis . 13 2.2.2 Paracellular transport . 14 2.2.3 Efflux transport mediated by P-glycoprotein . 14 2.2.4 Distribution, Metabolism and Excretion . 16 2.3 Excipients . 17 2.3.1 Surfactants . 17 2.3.1.1 HLB-system . 18 2.3.1.2 Anionic surfactants . 19 2.3.1.3 Cationic surfactants . 20 2.3.1.4 Zwitterionic surfactants . 20 2.3.1.5 Non-ionic surfactants . 20 2.4 Models used for drug permeability studies . 27 2.4.1 In vivo models to study drug absorption . 27 x 2.4.2 In situ model to study drug absorption . 27 2.4.3 In vitro / Ex vivo models to study drug absorption . 28 2.5 Animal tissue-based in vitro models for permeability studies . 28 2.5. 1 Sweetana-Grass diffusion chambers . 28 2.5. 1.1 Porcine intestinal tissue . 30 2.5. 1.1.1 Murine intestinal tissue . 31 2.5. 1.1.2 Everted sac . 32 2.5. 2 Cell culture-based in vitro models for permeability studies . 33 2.5. 2.1 Colorectal adenocarcinoma cell line (Caco-2) . 33 2.5. 2.2 Madin Darby canine kidney (MDCK) cells . 34 2.6 Conclusion . 34 CHAPTER 3: EXPERIMENTAL METHODS . 36 3.1 Materials . 36 3.2 Preparation of materials . 37 3.3 Tissue preparation. 37 3.4 Membrane viability evaluation . 41 3.4.1 Trans-epithelial electrical resistance (TEER) . 41 3.4.2 Evaluation of intestinal integrity by Lucifer Yellow. 42 3.5 Bidirectional transport across porcine intestinal tissue. 42 3.6 Florescence detection . 43 3.7 Validation of analytical method for measuring Rho123 . 43 3.7. 1 Linearity . 44 3.7. 2 Accuracy . 45 xi 3.7. 3 Specificity . 46 3.7. 4 Precision . 47 3.7. 4.1 Intra-day precision (repeatability) . 48 3.7. 4.2 Inter-day precision . 48 3.7. 5 Limits of detection and quantification . 49 3.8 Conclusion of validation . 49 CHAPTER 4: RESULTS AND DISCUSSION . 50 4.1 In vitro transport of Lucifer Yellow . 50 4.2 In vitro transport of Rhodamine 123 (control group) . 51 4.3 In vitro bidirectional transport of Rho123 in the presence of Brij 58 . 54 4.3.1 Discussion . 57 4.4 In vitro bidirectional transport of Rho123 in the presence of Cremophor CO40 . 58 4.4.1 Discussion . 61 4.5 In vitro transport Rho123 in the presence of Tween 20 . 62 4.5. 1 Discussion . 66 4.6 In vitro transport of Rho123 in the presence of Span 20. 66 4.6. 1 Discussion . 70 4.7 In vitro transport of Rho123 in the presence of Sodium deoxycholate. 70 4.7. 1 Discussion . 74 4.8 Conclusion . 75 CHAPTER 5: FINAL CONCLUSIONS AND FUTURE RECOMMEN