Biopharmaceutical Aspects of Oral Drug Delivery
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BIOPHARMACEUTICAL ASPECTS OF ORAL DRUG DELIVERY BIOPHARMACEUTICAL ASPECTS OF ORAL DRUG DELIVERY Biofarmaceutische aspecten van orale toediening van medicijnen Met een samenvatting in het Nederlands Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de Rector Magnificus, Prof. Dr. W.H. Gispen, ingevolge het besluit van het College voor Promoties in het openbaar te verdedigen op vrijdag 3 september 2004 des ochtends te 10:30 uur Door Werenfriedus Adrianus Faassen Geboren op 17 februari 1964, te Ede Promotor: Prof. Dr. H. Vromans, Universiteit Utrecht, Faculteit der Farmaceutische Wetenschappen Dit proefschrift werd mogelijk gemaakt met de financiële steun van Organon NV ISBN 90-393-3756-X Contents CONTENTS 1 BIOPHARMACEUTICAL ASPECTS OF ORAL DRUG DELIVERY IN DRUG 9 RESEARCH AND DEVELOPMENT. 1.1 Introduction. 9 1.2 Drug Research and Development. 11 1.2.1 Preclinical and early clincial development. 13 1.2.2 Clinical development. 14 1.2.3 Registration. 15 1.2.4 Oral drug delivery. 15 1.3 Aim of thesis. 17 1.4 References. 18 2 PHYSICOCHEMICAL PROPERTIES REQUIRED FOR AN OPTIMAL 19 SYSTEMIC AVAILABILITY OF DRUGS IN RELATION TO THE ROUTE OF ADMINISTRATION. 2.1 Introduction. 20 2.2 Experimental. 21 2.3 Results. 22 2.3.1 Physiological / Anatomical overview. 22 2.3.1.1 Absorption barriers. 22 2.3.1.2 Metabolism for the different routes of administration. 29 2.3.1.3 (Active) Transport for the different routes of administration. 32 2.3.2 Physicochemical properties. 33 2.4 Discussion. 33 2.5 Conclusions. 41 2.6. References. 41 3 PHYSICOCHEMICAL PROPERTIES AND TRANSPORT OF STEROIDS 47 ACROSS CACO-2 CELLS. 3.1 Introduction. 48 3.2 Methods. 49 3.2.1 Calculation of the molecular descriptors of steroids. 49 3.2.2 Compounds tested in the Caco-2 cell system. 49 3.2.3 Caco-2 cell system. 50 3.2.4 Calculations 54 3.2.5 Solubility. 54 3.2.6 Concentration measurements. 54 3.3 Results and discussion. 54 3.4 Conclusions. 63 3.5 References. 63 4 CACO-2 PERMEABILITY, P-GLYCOPROTEIN TRANSPORT RATIOS AND 67 BRAIN PENETRATION OF HETEROCYCLIC DRUGS. 4.1 Introduction. 68 4.2 Materials and Methods. 68 4.2.1 Compounds tested. 68 4.2.2 Calculation of the physicochemical properties. 69 4.2.3 Cell culture. 70 4.2.4 Drug transport experiments. 70 4.2.5 Calculations. 72 4.2.6 Concentration measurements. 72 4.3 Results and Discussion. 72 4.3.1 Caco-2 permeability data. 72 Contents 4.3.2 P-glycoprotein transport. 73 4.4 Conclusions. 81 Acknowledgements. 82 4.5 References. 82 5 A FEASIBILITY STUDY INTO THE PREDICTION OF LYMPHATIC DRUG 85 DELIVERY. 5.1 Introduction. 86 5.2 Materials and methods. 88 5.2.1 Calculation of molecular descriptors. 88 5.2.2 Materials. 88 5.2.3 Ex vivo lymph from beagle dogs. 88 5.2.4 Partitioning of drugs with intralipid and lymph. 89 5.2.5 Density gradient ultracentrifugation. 89 5.2.6 Concentration measurement of testosterone esters with HPLC. 90 5.2.7 Concentration measurement of [3H] and [14C] labeled drugs. 91 5.2.8 Caco-2 experiments. 91 5.2.8.1 Cell culture. 91 5.2.8.2 Induction of CM secretion in Caco-2 cells. 92 5.2.8.3 Transport study of T, TU and MB. 93 5.3 Results and Discussion. 93 5.3.1 Prediction of lymphatic drug delivery with molecular descriptors. 93 5.3.2 Partitioning of testosterone esters to the lipid fraction of Intralipid and ex 95 vivo dog lymph. 5.3.3 Caco-2 experiments. 97 5.4 Conclusions. 101 5.5 References. 102 6 CONTRIBUTION OF LYMPHATICALLY TRANSPORTED 105 TESTOSTERONE UNDECANOATE TO THE SYSTEMIC EXPOSURE OF TESTOSTERONE AFTER ORAL ADMINISTRATION OF TWO ANDRIOL FORMULATIONS IN CONSCIOUS LYMPH DUCT-CANNULATED DOGS. 6.1 Introduction. 106 6.2 Materials and methods. 107 6.2.1 Materials. 107 6.2.2 Extemporaneous preparation of an Intralipid formulation of [2H]-TU. 107 6.2.3 Oral formulations of TU. 108 6.2.4 Surgical procedures. 108 6.2.5 Experimental procedures. 108 6.2.6 Analytical procedures. 109 6.2.7 Serum concentrations of TU/DHTU. 109 6.2.8 Lymph concentrations of TU/DHTU. 110 6.2.9 Lymph and serum concentrations of T/DHT. 111 6.2.10 [2H]-TU in Intralipid. 112 6.2.11 Acceptance criteria for HPLC and GC assays. 112 6.2.12 Lymph concentrations of triglyceride. 113 6.2.13 Data analysis. 113 6.2.14 Analysis of serum pharmacokinetic profiles. 113 6.2.15 Statistical analysis. 114 6.3 Results. 115 6.3.1 Systemic serum concentrations after i.v. administration of [2H]-TU. 115 6.3.2 Lymphatic transport and portal concentrations after oral administration of 115 TU. 6.3.3 Systemic serum concentrations of TU, DHTU, T, and DHT. 120 6.3.4 Systemic exposure of TU and T. 120 Contents 6.4 Discussion. 123 6.4.1 Systemic serum concentrations after i.v. administration of [2H]-TU. 125 6.4.2 Absorption into lymph after oral TU administration. 126 6.4.3 Contribution of lymphatic and blood absorption to systemic availability of 127 TU. 6.4.4 Factors contributing to systemic T exposure. 128 6.5 Conclusion. 128 6.6 References. 129 7 BIOWAIVERS FOR ORAL IMMEDIATE RELEASE PRODUCTS: 131 IMPLICATIONS OF LINEAR PHARMACOKINETICS. 7.1 Introduction. 132 7.2 Experimental. 134 7.2.1 Materials. 134 7.2.2 Bile fluids beagle dogs. 134 7.2.3 Solubility determination in bile fluids. 134 7.2.4 High performance liquid chromatography. 135 7.2.5 Single dose pharmacokinetic study with Org 4060. 135 7.3 Results. 136 7.3.1 Reflections on solubility: low solubility drugs. 136 7.3.1.1 Ketoprofen and Naproxen (reference drugs from the 136 Biopharmaceutical Classification System). 7.3.1.2 Steroids. 138 7.3.2 Reflections on permeability: P-glycoprotein (Pgp) transported drugs. 140 7.4 Discussion. 142 7.5 References. 144 SUMMARY. 147 DANKWOORD. CURRICULUM VITAE. Contents Introduction 1 Biopharmaceutical aspects of oral drug delivery in drug research and development. 1.1 Introduction. From an historical point of view (bio) pharmaceutical sciences have evolved from alchemy to a science driven approach to seek cure and relief for the ill persons (Rang and Dale, 1987; Pratt and Taylor, 1990). In the 17th century, the scientific founder of chemistry Robert Boyle (1692) was satisfied when dealing with therapeutics to describe and recommend mixtures of worms, dung, urine, and the moss from a dead man’s skull. Blood letting, vomiting, and purgatives were standard treatments and many patients died due to these methods. As a reaction Hahnemann introduced homeopathy in the early nineteenth century, stating that the efficacy could be enhanced by dilution. The system rapidly drifted into absurdity as dilutions up to 1060 were recommended, being equivalent to one molecule in a sphere with the size of the orbit of Neptune. The dogmatic approaches hindered scientific progress and many therapies were introduced and disappeared (Ryan et al., 2000). This lasted till the end of the 18th century when empirism was replaced by a scientific approach, in a slow and gradual process, until the mid 19th century. In the second half of the 19th century, medical sciences changed dramatically as the industrial revolution brought technology and chemistry. From the 1860's onwards, the relationship between the chemical structure of a drug and its pharmacological action was studied systematically (Ryan et al., 2000). The Cambridge physiologist John Newport Langley (1852 - 1925) and the Berlin immunologist Paul Ehrlich (1854 - 1910) developed the receptor theory over the period 1870 – 1910 (Maehle et al., 2002). Nowadays, it is generally accepted that most drugs act by binding to specific macromolecules (receptors), either inside or onto the cells surface, to change their biochemical or biophysical activity and thus their cellular function. The currently known therapeutic targets can be divided into several main classes (Fig. 1). The theory of receptors was improved through the new quantitative approach developed by the Edinburgh pharmacologist Alfred Joseph Clark (1885 - 1941) in the early 1930's (Maehle et al., 2002). Modifications to this receptor occupancy theory - 9 Chapter 1 by Ariens (Utrecht) in 1954 and by Stephenson (Edinburgh) in 1956 - accounted for the intrinisic activity (efficacy) of a drug (its ability to induce an effect after binding). Fig. 1. Therapeutic target classes. All current therapeutic targets can be subdivided into seven main classes, wherein enzymes and receptors represent the largest part. (Bleicher et al., 2003) In the pharmaceutical industry, new drugs are discovered and developed during a long and costly process. Safety and efficacy need to be evaluated in animal and human studies. However, this is only possible when a drug is absorbed in order to reach the systemic circulation and is transported to the receptors. Hence, the relationship between the physicochemical properties of the drug, dosage form, formulation, and (human) physiology need to be studied in biopharmaceutical studies. The physicochemical properties determine whether a drug can be absorbed into the blood, which transports it to the desired site of action. The dosage form and formulation need to be optimized to facillitate an efficient and reproducible absorption process. Human physiology influences the necessary physicochemical properties, the dosage form, and formulation. The results of the biopharmaceutical studies are used to optimize the pharmacological or therapeutical effectivity of the drugs. To illustrate the position of the biopharmaceutical sciences in the research and development process of new medicines this subject is discussed into more detail. 10 Introduction 1.2 Drug Research and Development.