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Photographs included in the original manuscript have been reproduced xerographically in this copy. 35 mm slides or 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. Accessing the World’sUMI Information since 1938 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA Order Number 8804083 Drug stabilization through molecular modification: Hydrolysis kinetics of ampicillin prodrugs and nucleoside analogs Nguyen, Ngoc-Anh Thi, Ph.D. The Ohio State University, 1987 UMI 300 N. Zccb Rd. Ann Arbor, MI 48106 DRUG STABILIZATION THROUGH MOLECULAR MODIFICATION: HYDROLYSIS KINETICS OF AMPICILLIN PRODRUGS AND NUCLEOSIDE ANALOGS DISSERTATION Presented In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Ngoc-Anh T. Nguyen, B.S. >!t >|c ilc >!< )|i The Ohio State University 1907 Dissertation Committee: Approved by Robert E. Notari, Ph.D. Theodore D. Sokoloski, Ph.D. Alfred E. Staubus, Ph.D. A dviser College of Pharmacy DEDICATION To Mom and Dad Cong cha nhx? nul Thai S<3n, Nghia^ me nhu 9 nu<3ca * trong nguon chay ra.9 ' MotA longv th<3 “me kinh7 cha • * Cho tron chvl hieu moi la clao con. 9 - ii - ACKNOWLEDGEMENTS I wish to sincerely thank my adviser, Professor Robert E. Notari, for his patience, invaluable advice and thoughtful guidance. His insights and generosity of time were instrumental in the completion of this project. I have learned much from the Pharmaceutics faculty, staff, and fel­ low graduate students and have appreciated their kindness and friend­ ship. In particular, I thank Dr. Louis Malspeis for the loan of equip­ ment in time of crisis, for helpful discussions, and for his generosity and support. I like to particularly thank Mehdl Mansoorl for his encouragement and support through my undergraduate and graduate studies. I especially wish to thank Mom and Dad for their love and support. The financial support from the College of Pharmacy is appreciated. I would also like to thank: Dr. J.L. DeYoung and the Wyeth Co. for Ampicillin Dr. J.B. D'Silva and Pfizer Inc. for Bacamplcillin Dr. Tokuji Suzuki, University of Chiba, Dr. Shigeo Kawamura and Yamanouchi Pharmaceuticals, Japan, for Talampicillin. - H i - VITA May 15, 1959 ............................................Born - Trung Hieu, Vinh Long, Viet Nam. 1982 ................................................................B . S ., C hem istry The University of Michigan Ann Arbor, Michigan 1982-1987 .....................................................Graduate Teaching Associate The Division of Pharmaceutics and Pharmaceutical Chemistry College of Pharmacy The Ohio State University Columbus, Ohio FIELD OF STUDY Major Field: Pharmaceutics and Pharmaceutical Chemistry TABLE OF CONTENTS PAGE DEDICATION ................................................................................................................ ii ACKNOWLEDGEMENTS ................................................................................................iii VITA ................................................................................................................................. iv LIST OF TABLES ........................................................................................................... vii LIST OF FIGURES ........................................................................................................ ix CHAPTER 1. DEVELOPMENT OF REVERSE-PHASE HPLC ASSAYS FOR AMPICILLIN AND ITS PRODRUGS.............................................. 2 SUMMARY ................................................................................................... 3 INTRODUCTION ......................................................................................... 4 EXPERIMENTAL ......................................................................................... 7 RESULTS AND DISCUSSION ............................................................... 8 REFERENCES ........................................................................................... 16 2. KINETICS OF PRODRUG STABILITY: BACAMPICILLIN AND TALAMPICILLIN ......................................................................26 SUMMARY....................................................................................................27 INTRODUCTION .......................................................................................28 EXPERIMENTAL .......................................................................................38 RESULTS ....................................................................................................40 DISCUSSION ........................................................................................... 48 REFERENCES ........................................................................................... 58 - v - 3. KINETIC REQUIREMENTS FOR OPTIMIZATION OF PRODRUG UTILIZATION TIME ................................................ 93 SUMMARY....................................................................................................94 INTRODUCTION .......................................................................................95 EXPERIMENTAL .....................................................................................106 RESULTS AND DISCUSSION .............................................. 109 REFERENCES .........................................................................................125 4. SUBSTITUENT EFFECTS ON DEGRADATION RATES AND PATHWAYS OF CYTOSINE NUCLEO SIDES.........................139 SUMMARY..................................................................................................140 INTRODUCTION .....................................................................................141 EXPERIMENTAL .....................................................................................145 RESULTS ..................................................................................................149 DISCUSSION ......................................................................................... 157 REFERENCES ......................................................................................... 167 - vi - LIST OF TABLES TABLE PAGE 1.1 Retention Times of Ampicillin With and Without Tetrabutylammonium H ydroxide ............................................... 19 1.2 Retention Times of Ampicillin and Bacampicillin with Heptane sulfonate S odium ..........................................................................20 1.3 Isocratic Assays of Ampicillin and its P rodrugs ........................... 21 2.1 Summary of Rate Constants for Bacampicillin ................................61 2.2 Summary of Rate Constants for Ampicillin ........................................ 63 2.3 Summary of Rate Constants for Ampicillin and Bacampicillin in the Absence of B uffers ............................................65 2.4 Summary of Rate Constants for Talamplcillin . ........................ 6 6 2.5 HPLC Assays for Ampicillin, Bacampicillin and Talampicillin ....................................................................................................6 8 2.6 Summary of Catalytic Constants and Energetics .............................69 2.7 Catalytic Constants Defining Conversion and Degradation ................................................... 70 2.8 General Acid and General Base Catalytic Constants . 71 2.9 Utilization Time for Ampicillin, Bacampicillin and Talampicillin ....................................................................................................72 4.1 Rate Constants for 5-Methyldeoxycytidine Degradation . 169 4.2 Rate Constants for Substituted and Unsubstituted Cytosine N ucleosides .................................................................................170 4.3 HPLC Characteristics of Nucleosides and B a se s ...................... 171 4.4 Total Recovery of 5-Methyldeoxycytidine at pH 4.58 . 172 4.5 Total Recovery of 6 -Methylcytidine at pH 3.63 173 - vii - 4.G Total Recovery of Arablnosylcytosine at pH 1.14 .......................... 174 4.7 Recovery of G-Methylarabinosylcytosine at pH 1.14 . 175 - v i i i - LIST OF FIGURES HPLC chromatograms of bacampicillin (1) and ampicillin (3) in a ...................................................................... 22 HPLC chromatograms of ampicillin in the absence (A ,B ) ................................................................................................ 23 HPLC chromatograms of bacampicillin (A) and ampicillin (B ) ....................................................................................