xxvii CONTENTS Abstract List of Tables List of Figures Abbreviations List of Chemicals

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1 xii CONTENTS Abstract ix List of Tables xvii List of Figures xx Abbreviations xxv List of Chemicals xxvii List of Instruments xxix 1 INTRODUCTION Prodrugs Rational for the Use of Prodrugs Pharmaceutical Phase Use of Prodrugs to Overcome Pharmaceutical Barriers Masking Taste or Odour Minimizing Pain at Site of Injection Alteration of Drug Solubility Enhancement of Chemical Stability Pharmacokinetic Phase Use of Prodrugs to Overcome Pharmacokinetic Barriers To Overcome Absorption Problems Enhancement of Oral Absorption Enhancement of Ophthalmic Absorption Enhancement of Percutaneous Absorption Prevention of Pre-systemic Metabolism Longer Duration of Action To Diminish Local and Systemic Toxicity of Drugs Classification of Prodrugs Carrier Linked Prodrugs Tripartite Prodrugs Mutual Prodrugs Polymeric Prodrugs Bioprecursors 20

2 xiii 1.8 Bio Reversible Derivatives for Various Functional Groups Esters Prodrug for Amide, Imides and Other Acidic Compounds N Mannich Bases and Acyloxy 21 Derivatives N Acyl Derivatives N Hydroxy Methyl Derivatives Prodrugs for Amines N (Acyloxy alkoxy carbonyl) Derivatives 24 and Amide Derivatives Oxazolidines Prodrugs with Carbonyl Groups Thiazolidines Enol Esters The Double Prodrug Concept Site Specific Drug Delivery Site Directed Drug Delivery Localized Drug Delivery Systemic Site Specific Delivery Site Specific Bioactivation Kidney Colon Stomach NSAIDs Mechanism of Action Beneficial Actions Due to Inhibition of 35 PG Synthesis Adverse Effects of NSAIDs 36 2 LITERATURE REVIEW Research Envisaged Objectives 63

3 xiv 3 MONOGRAPH AND ANALYTICAL PROFILE OF DRUGS Selection of Drugs Standardization of Drugs Profile of Aceclofenac General Characteristics Methods of Analysis Profile of Mefenamic Acid General Characteristics Methods of Analysis Profile of Dexibuprofen General Characteristics Methods of Analysis 73 4 EXPERIMENTAL INVESTIGATIONS Methodology Materials and Instruments Synthesis of Prodrugs Synthesis of Amide Prodrugs of Aceclofenac Synthesis of Amide Prodrugs of Mefenamic Acid Synthesis of Amide Prodrugs of Dexibuprofen Characterization of Drugs and Prodrugs Thin Layer Chromatography Melting Point Determination Molecular Weight Determination Solubility Studies Elemental Analysis Spectral Analysis UV Absorption Studies Preparation of Calibration Curve of 90 Aceclofenac Preparation of Calibration Curve of 92 Mefenamic Acid

4 xv Preparation of Calibration Curve of 93 Dexibuprofen Determination of Partition Coefficient Protein Binding Studies Hydrolysis Study of Synthesized Prodrugs In vitro Hydrolysis Study Acid Catalyzed Hydrolysis Base Catalyzed Hydrolysis Hydrolysis Rate Determination of Prodrugs In Simulated Gastric Fluid (ph 1.2) In Simulated Intestinal Fluid (ph 7.4) In Rat Fecal Matter (ph 7.4) In 80 % Human Plasma (ph 7.4) Kinetics of Drug Hydrolysis Pharmacological Screening of Drugs and Prodrugs Experimental Animals Anti Inflammatory Activity Screening Methods Experimental Method Analgesic Activity Screening Methods Experimental Method Ulcerogenic Activity Experimental Method Histopathological Studies Experimental Method EXPERIMENTAL RESULTS Characterization of Aceclofenac Synthesis of Aceclofenac Prodrugs Characterization of Aceclofenac Prodrugs Hydrolysis Studies of Aceclofenac Prodrugs Pharmacological Study of Aceclofenac Prodrugs Anti Inflammatory Activity 137

5 xvi Analgesic Activity Ulcerogenic Activity Histopathological Studies Characterization of Mefenamic Acid Synthesis of Mefenamic Acid Prodrugs Characterization of Mefenamic Acid Prodrugs Hydrolysis Studies of Mefenamic Acid Prodrugs Pharmacological Study of Mefenamic Acid Prodrugs Anti Inflammatory Activity Analgesic Activity Ulcerogenic Activity Histopathological Studies Characterization of Dexibuprofen Synthesis of Dexibuprofen Prodrugs Characterization of Dexibuprofen Prodrugs Hydrolysis Studies of Dexibuprofen Prodrugs Pharmacological Study of Dexibuprofen Prodrugs Anti Inflammatory Activity Analgesic Activity Ulcerogenic Activity Histopathological Studies SUMMARY OF RESULTS CONCLUSION AND RECOMMENDATION 212 BIBLIOGRAPHY 216 RESEARCH PUBLICATIONS 247