UNIVERSITY OF CINCINNATI DATE: October 19, 2002 I, Ehab Hamed , hereby submit this as part of the requirements for the degree of: Doctor of Philosophy in: Pharmaceutical Sciences/ Industrial Pharmacy It is entitled: Application and Evaluation of Extended Release Technology To Loop Diuretics Approved by: William Cacini, Ph.D. Pankaj Desai, Ph.D. Myron Gerson, M.D. Ronald Millard, Ph.D. Adel Sakr, Ph.D. APPLICATION AND EVALUATION OF EXTENDED RELEASE TECHNOLOGY TO LOOP DIURETICS A Dissertation submitted to the Division of Research and Advanced Studies of the University of Cincinnati in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY (Ph.D.) in the Department of Pharmaceutical Sciences of the College of Pharmacy 2002 by Ehab Ahmed Mamdouh Hamed B.Sc., Assiut University, Egypt, 1996 Committee Chair: Adel Sakr, Ph.D. Abstract Loop diuretics offer great advantages in treating edematous states associated with congestive heart failure, liver cirrhosis and kidney failure owing to their intense diuretic effect. Evidences suggested the diuretic effect can be exaggerated by careful control of the rate at which loop diuretics are made available to the urinary tubules. If optimally designed, peroral extended release formulation can provide better utilization of the same total dose of loop diuretic, an effect of utmost importance in edematous patients with high resistance to loop diuretics. Bumetanide multiparticulate immediate and extended release formulations were developed and tested in rabbits. A novel multiple response optimization technique based on superimposing contour diagrams was developed and successfully used to optimize bumetanide release. Instability in drug release from multiparticulate formulations after storage warrants in depth investigation of different formulation and processing factors controlling drug release. Curing time, temperature, plasticizer level, coating polymer lipophilicity, and the use of hydrophilic seal coat were explored in this study. The findings proved instability in bumetanide release is attributed to drug migration into the film coat during storage. Careful selection of plasticizer level and curing conditions together with the use of hydrophilic seal coat prevented drug migration and stabilized drug release after storage. When compared to immediate release formulation in rabbits, equivalent amounts of bumetanide were excreted from both formulations yet at different rates. The slow delivery of bumetanide from the extended release formulation improved its diuretic and natriuretic efficiencies within the first day after dosing. The activation of compensatory mechanisms is thought to diminish the response to extended release bumetanide formulation within the second day. While providing comparable diuretic and saliuretic effects to that of immediate release formulation, extended release bumetanide formulation can offer the advantage of avoiding the initial, unpleasant and intense diuretic effect experienced with immediate release formulations. Dedication This dissertation is dedicated to my parents in the utmost appreciation and gratitude for their unconditional love, support and continuous encouragement throughout every step in my life. No words or deeds can ever thank them enough for what they blessed me with. Acknowledgements I would like to thank my dissertation committee: Dr. W. Cacini, Dr. P. Desai, Dr. M. Gerson, Dr. R. Millard, and Dr. A. Sakr for their valuable guidance throughout the course of my research. I wish to express special word of thanks to Dr. A. Sakr, my committee chairman for his support both financially and emotionally. Dr. Sakr dealt with me in a fatherly attitude and provided me with constructive criticism that helped me develop the skills required to fulfill my research needs. It was Dr. Sakr's affection and enthusiasm to Industrial Pharmacy research that brought me to this arena and inspired me with the required endurance to face the day-to-day challenges of my research. It is fair to say that without Dr. Sakr's guidance and support, this work would have never been possible. I would like to thank Dr. R. Millard for his guidance and valuable scientific advice in my animal study. Dr. Millard's shared with me some of his great experience and wisdom that helped me not only in my research studies but also in my life perspective. I find my contact with Dr. Millard very fruitful for the development of my research skills. I would like also to thank Dr. M. Gerson for his confidence in my abilities and the financial support to pursue my research goals. I would like to thank Dr. Desai for providing the fluorescence detector needed for my analytical work. I would like to thank Dr. W. Cacini for providing the chart recorder needed for my analytical work. I would like to thank Dr. M. Kurtzman from the Laboratory Animals Medical Services (LAMS) for his indispensable help in the animal study. I would like to thank Dr. H. Amlal from the department of Nephrology for his help with the urine analysis. I would like to thank Dr. H. Al-Khalidi from Procter and Gamble for his advice regarding the statistical treatment of my data. I would like to acknowledge the generous donation of Eudragit RS 30 D from Rohm America. Special thanks go to Mr. A. Honeycheck for his sincere help and support. Finally, I would like to thank my colleagues in the Industrial Pharmacy Program for their needed friendship, cooperation and understanding. Table of Contents Page 1. Introduction 14 1.1. Definition 14 1.2. Pharmacodynamic Rationale for Formulating Loop 14 Diuretics as Extended Release Dosage Forms 1.3. Rationale for Selecting Bumetanide as Model Drug for the 20 Study 1.4. Peroral Extended Release Formulation Design Strategy 25 1.4.1. Diffusion-Controlled Extended Release Formulations 25 1.4.1.1. Reservoir Devices 25 1.4.1.2. Matrix Devices 26 1.4.2. Dissolution-Controlled Extended Release Formulations 26 1.4.3. Osmotic-Controlled Extended Release Formulations 27 1.4.4. Extended Release Formulation Based on Ion Exchange 28 Resin 1.5. Multiparticulate Drug Delivery System 28 1.5.1. Definition and Advantages 28 1.5.2. Manufacture of Multiparticulate Drug Delivery Systems 29 1.5.2.1. Extrusion/ Spheronization Process 29 1.5.2.2. The Use of Fluid Bed Equipment in Pelletization and 31 Coating of Multiparticulate Drug Delivery Systems 1.5.2.2.1. Types of Fluid Bed Equipment 32 1.5.2.2.1.1. Top Spray Fluid Bed 32 1.5.2.2.1.2. Bottom Spray Fluid Bed (Wurster Coater) 32 1 1.5.2.2.1.3. Tangential Spray Fluid Bed (Rotary Fluid Bed) 34 1.5.2.3. Coating of Multiparticulate Systems 34 1.5.2.3.1. Coating of Multiparticulate Systems Using Aqueous 35 Polymeric Dispersion 1.5.2.3.2. Factors to be Considered in Coating of Multiparticulate 36 Systems in Fluid Bed Equipment 1.5.2.3.2.1. Film Forming Temperature 36 1.5.2.3.2.2. Plasticizers 37 1.5.2.3.2.3. Fluidization Air Temperature 39 1.5.2.3.2.4 Spray Rate 39 1.5.2.4. Curing of Coated Multiparticulate System 40 1.6. Optimization of Drug Release from Coated Multiparticulate 42 Systems Using Statistical Modeling 2. Hypothesis 45 3. Objective 45 4. Specific Aims 45 5. Experiment and Methodology 46 5.1. Materials and Supplies 46 5.2. Equipment 47 5.3. Software 48 5.4. Methods 49 5.4.1. Part I: Development and Optimization of Bumetanide 49 Extended Release Formulations Using Response Surface Methodology and Multiple Response Optimization 5.4.1.1. Layering of Bumetanide onto Nu-pariels Sugar Pellets 49 5.4.1.2. Development of Bumetanide Spectrofluorimetric Analytical 50 Method 2 5.4.1.3. Validation of Bumetanide Analytical Method 53 5.4.1.4. Content Uniformity Assessment 53 5.4.1.5. Coating of Bumetanide-Loaded Pellets 54 5.4.1.6. Testing the Release of Bumetanide from Coated Pellets 55 5.4.1.7. Testing the Effect of Dissolution Media pH on the Release 58 of Bumetanide from Coated Pellets 5.4.1.8. Testing the Effect of Agitation Speed on the Release of 58 Bumetanide from Coated Pellets 5.4.1.9. Statistical Analysis and Optimization of Bumetanide 59 Release 5.4.1.10 Preparation and Statistical Evaluation of the Designed 60 Formulation 5.4.2. Part II: Study of the Effect of Curing Conditions and 61 Plasticizer Level on The Release of Bumetanide from Coated Pellets 5.4.2.1. Statistical Experimental Design 61 5.4.2.2. Coating of Bumetanide-Loaded Pellets 63 5.4.2.3. Curing of Coated Pellets 63 5.4.2.4. Testing the Release of Bumetanide from Cured Coated 65 Pellets 5.4.2.5. Seal Coating with Hydroxypropyl Methyl Cellulose (HPMC 65 LV 100) 5.4.2.6. Coating using a Mixture of Eudragit RS and Eudragit RL 65 5.4.2.7. Use of Sodium Chloride as a Channeling Agent in the 68 Coating Formulation 5.4.2.8. Study the Effect of Storage on the Release of Bumetanide 71 from Coated and Cured Pellets 5.4.2.9. Statistical Analysis 71 3 5.4.3. Part III: Testing Selected Optimized Bumetanide Extended 72 Release Formulation in Laboratory Animals 5.4.3.1. Selection of Animal Model 72 5.4.3.1.1. Reasons for Selecting Rabbit as the Animal Model 72 5.4.3.2. Animal Study Design 76 5.4.3.3. Rationale for the number of rabbits used 77 5.4.3.4. Rabbits Manipulation 79 5.4.3.4.1 Rabbits Restraint 79 5.4.3.4.2. Drug Administration 80 5.4.3.4.3. Sample Withdrawal 80 5.4.3.5. Analysis of Blood and Urine Sample for Bumetanide 81 Contents 5.4.3.5.1. Development of HPLC Analytical Method 81 5.4.3.5.2.