EXTEMPORANEOUSLY COMPOUNDED TOPICAL CALCIUM CHANNEL BLOCKERS FOR WOUNDS AND SKIN ULCERS by Arezou Teimouri Submitted in partial fulfilment of the requirements for the degree of Master of Science at Dalhousie University Halifax, Nova Scotia July 2019 © Copyright by Arezou Teimouri, 2019 TABLE OF CONTENTS LIST OF TABLES ........................................................................................................... iv LIST OF FIGURES ........................................................................................................ vii ABSTRACT ....................................................................................................................... x LIST OF ABREVIATIONS AND SYMBOLS USED .................................................. xi ACKNOWLEDGEMENTS ........................................................................................... xii CHAPTER 1 INTRODUCTION ..................................................................................... 1 1.1 ANATOMY AND PHYSIOLOGY OF THE SKIN .............................................................. 1 1.2 WOUND HEALING PROCESS ........................................................................................... 2 1.3 TOPICAL FORMULATIONS AND DRUG DELIVERY ................................................... 4 1.3.1 Semi-solid Dermatological Formulations ....................................................................... 4 1.3.2 Mechanisms of Dermatological Drug Delivery .............................................................. 4 1.4 CALCIUM CHANNEL BLOCKERS ................................................................................... 5 1.4.1 Pharmacology of Nifedipine and Diltiazem .................................................................... 5 1.4.2 Physicochemical Characteristics of Nifedipine and Diltiazem ....................................... 6 1.4.3 Clinical Application and Research on Topical Use of Calcium Channel Blockers ........ 8 1.5 IN VITRO ASSAYS .............................................................................................................. 9 1.5.1 Drug Release Testing ...................................................................................................... 9 1.5.2 Stability Testing ............................................................................................................ 10 CHAPTER 2 RESEARCH PROPOSAL AND OBJECTIVES .................................. 13 CHAPTER 3 RELEASE AND STABILITY OF COMPOUNDED TOPICAL NIFEDIPINE ................................................................................................................... 14 3.1 CHEMICALS ...................................................................................................................... 14 3.2 EQUIPMENT AND OTHER SUPPLIES............................................................................ 14 3.3 METHODS .......................................................................................................................... 15 3.3.1 Spectrophotometry Method Validation ......................................................................... 15 3.3.2 HPLC Conditions .......................................................................................................... 17 3.3.3 HPLC Stability Indicating Method Validation ............................................................. 18 3.3.4 Compounding of Formulations ..................................................................................... 19 3.3.5 Drug Extraction Method ............................................................................................... 21 3.3.6 Drug Release Studies .................................................................................................... 22 3.3.7 Stability Testing ............................................................................................................ 24 3.3.8 Data Analysis ................................................................................................................ 26 3.4 RESULTS ............................................................................................................................ 26 ii 3.4.1 Spectrophotometry Method Validation ......................................................................... 26 3.4.2 HPLC Stability Indicating Method Validation ............................................................. 31 3.4.3 Drug Extraction Method ............................................................................................... 37 3.4.4 Nifedipine Release Studies ........................................................................................... 39 3.4.5 Stability Testing: pH Measurement Method and Controls ........................................... 44 3.4.6 Stability of Nifedipine in Glaxal Base™ ...................................................................... 50 3.4.7 Stability of Nifedipine in K-Y® Jelly ........................................................................... 54 3.4.8 Stability of Nifedipine in Aquaphor® Healing Ointment ............................................. 58 3.5 DISCUSSION ...................................................................................................................... 61 CHAPTER 4 RELEASE AND STABILITY OF COMPOUNDED TOPICAL DILTIAZEM ................................................................................................................... 65 4.1 CHEMICALS ...................................................................................................................... 65 4.2 EQUIPMENT AND OTHER SUPPLIES............................................................................ 65 4.3 METHODS .......................................................................................................................... 66 4.3.1 HPLC Conditions .......................................................................................................... 66 4.3.2 HPLC Stability Indicating Method Validation ............................................................. 67 4.3.3 Compounding of Formulations ..................................................................................... 69 4.3.4 Drug Release Studies .................................................................................................... 70 4.3.5 Stability Testing ............................................................................................................ 70 4.3.6 Drug Extraction Method ............................................................................................... 70 4.3.7 Data Analysis ................................................................................................................ 71 4.4 RESULTS ............................................................................................................................ 72 4.4.1 HPLC Stability Indicating Method Validation ............................................................. 72 4.4.2 Drug Extraction Method ............................................................................................... 76 4.4.3 Diltiazem Release Studies ............................................................................................. 77 4.4.4 Stability Testing: pH Measurement Method and Controls ........................................... 79 4.4.5 Stability of Diltiazem in Glaxal Base™ ........................................................................ 84 4.4.6 Stability of Diltiazem in a Hydroxyethyl Cellulose-based Gel ..................................... 88 4.4.7 Stability of Diltiazem in White Petrolatum ................................................................... 92 4.5 DISCUSSION ...................................................................................................................... 95 CHAPTER 5 SUMMARY AND CONCLUSION ........................................................ 98 5.1 FUTURE RESEARCH ...................................................................................................... 101 BIBLIOGRAPHY ......................................................................................................... 102 iii LIST OF TABLES Table 1 Physicochemical characteristics of nifedipine and diltiazem HCl. .................. 7 Table 2 Chromatographic conditions for nifedipine analysis (method #1). ................ 17 Table 3 Chromatographic conditions for nifedipine analysis (method #2). ................ 18 Table 4 Non-medicinal ingredients of Glaxal Base™, Aquaphor® Healing Ointment, and K-Y® Jelly. .............................................................................................. 20 Table 5 Precision and accuracy data collected over three days for nifedipine derivatization. ................................................................................................. 28 Table 6 Interference test with nifedipine derivatization method using common solvents. .......................................................................................................... 30 Table 7 Precision data for nifedipine in methanol: water (70:30) solvent using HPLC.. ........................................................................................................................ 33 Table 8 Accuracy data for nifedipine in methanol: water (70:30) solvent using HPLC. ........................................................................................................................ 34 Table 9 Forced degradation of nifedipine using acidic, basic, and heat stress. ..........