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Addis Ababa University School of Graduate Studies ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES PHYSICOCHEMICAL CHARACTERIZATION OF ACID MODIFIED DIOSCOREA STARCH AND ITS EVALUATION AS DIRECTLY COMPRESSIBLE EXCIPIENT AND DISINTEGRANT IN TABLET FORMULATIONS By Bilal Tessema (B. Pharm) May, 2014 Addis Ababa, Ethiopia 1 PHYSICOCHEMICAL CHARACTERIZATION OF ACID MODIFIED DIOSCOREA STARCH AND ITS EVALUATION AS DIRECTLY COMPRESSIBLE EXCIPIENT AND DISINTEGRANT IN TABLET FORMULATIONS A thesis submitted to the School of Graduate Studies of Addis Ababa University in partial fulfillment of the requirements for the Degree of Master of Science in Pharmaceutics By Bilal Tessema (B. Pharm) Under the supervision of Prof. Tsige Gebre-Mariam and Dr. Anteneh Belete, Department of Pharmaceutics and Social Pharmacy, School of Pharmacy, College of Health Sciences, Addis Ababa University 2 ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES PHYSICOCHEMICAL CHARACTERIZATION OF ACID MODIFIED DIOSCOREA STARCH AND ITS EVALUATION AS DIRECTLY COMPRESSIBLE EXCIPIENT AND DISINTEGRANT IN TABLET FORMULATIONS By Bilal Tessema (B. Pharm) Department of Pharmaceutics and Social Pharmacy School of Pharmacy Approved by: Name Signature Date Prof. Tsige Gebre-Mariam __________________ May 02, 2014 (Advisor) Dr. Anteneh Belete __________________ May 02, 2014 (Advisor) Dr. Fitsum F. Sahle __________________ May 02, 2014 (Examiner) Dr. Nisha Mary-Joseph __________________ May 02, 2014 (Examiner) 3 ACKNOWLEDGEMENTS First of all, I would like to express my sincere gratitude to my advisors Prof. Tsige Gebre- Mariam and Dr. Anteneh Belete for their valuable advice and follow-up throughout the course of my work. My deepest gratitude goes to Ethiopian Pharmaceutical Manufacturing (EPHARM) Sh.Co. for the gift of paracetamol powder, Chemical Enginering Department, Institute of Technology, AAU for allowing to use their spray dryer and the Ethiopian Geological Survey for providing access to X-ray diffractometer. My special appreciation also goes to the staff members of the Department of Pharmaceutics & Social Pharmacy and Pharmaceutical Chemistry & Pharmacognosy for their respective support during my entire work. I also want to thank Fekade Tefera, Tamrat, Abdo and all my classmates for their support and encouragement during this work. Last but not least, my acknowledgement goes to Addis Ababa University and University of Gondar for sponsoring my study. i TABLE OF CONTENTS ACKNOWLEDGEMENTS i TABLE OF CONTENTS ii LIST OF TABLES v LIST OF FIGURES vi ACRONYMS viii ABSTRACT ix 1. INTRODUCTION 1 1.1. Starch 1 1.2. Dioscorea plant and its starch 2 1.2.1 Overview of dioscorea plant 2 1.2.2 Dioscorea abyssinica 2 1.3 Modification of starches 3 1.3.1 Physical modification of starches 4 1.3.2 Chemical modification of starches 4 1.4 Acid modified starch 4 1.4.1 Acid modification of starch 4 1.4.2 Properties of acid modified starch 5 1.5 Tablet excipients 5 1.5.1 Direct compressible excipient 5 1.5.2 Tablet disintegrants 5 1.6 The present study 6 1.7 Objective of the study 8 1.7.1 General objective 8 1.7.2 Specific objectives 8 2. MATERIALS AND METHODS 9 2.1 Materials 9 2.1.1 Plant materials 9 2.1.2 Chemicals and solvents 9 2.2 Methods 9 2.2.1 Starch isolation 9 ii 2.2.2 Acid modification of Dioscorea abyssinica starch 10 2.2.3 Preparation of spray dried native and acid modified starches 10 2.2.4 The recovery yield of the starch after acid hydrolysis 10 2.2.5 Measurement of starch crystallinity 10 2.2.6 Infrared spectroscopy 11 ® 2.2.7 Characterization of starches and Starch 1500 11 2.2.7.1 Determination of density and related properties 11 2.2.7.2 Flow rate and angle of repose 11 2.2.7.3 Swelling power and solubility 12 2.2.7.4 Moisture content 12 2.2.7.5 Moisture sorption pattern 13 2.2.8 Compaction property of starches 13 2.2.9 UV calibration curve of paracetamol 13 2.2.10 Granulation 14 2.2.11 Tablet compression 15 2.2.11.1 Compression of granules into tablet 15 2.2.11.2 Direct compression 15 2.2.12 Evaluation of tablets 17 2.2.12.1 Weight, thickness and diameter 17 2.2.12.2 Crushing strength 17 2.2.12.3 Tensile strength 17 2.2.12.4 Friability 17 2.2.12.5 Disintegration test 17 2.2.12.6 Dissolution test 18 2.2.12.7 Statistical analysis 18 3. RESULTS & DISCUSSION 19 3.1 Acid recovery yield 19 3.2 Crystallinity of the starches 19 3.3 FTIR 21 3.4 Powder properties of starches 24 3.5 Solubility and swelling power 26 iii 3.6 Moisture sorption property 277 3.7 Compaction property of starches 29 3.8 Lubricant sensitivity of native and acid modified starches 31 3.8.1 Effect of lubricant concentration on crushing strength and friability 311 3.8.2 Effect of lubricant concentration on tensile strength 333 3.8.3 Effect of lubricant concentration on disintegration time 344 3.9 Dilution potential 35 3.9.1 Weight variation and thickness 36 3.9.2 Crushing strength, tensile strength and friability 37 3.9.2 Disintegration time of directly compressed paracetamol tablets 39 3.9.3 Dissolution of directly compressed paracetamol tablet 40 3.10 Evaluation of paracetamol tablet at different disintegrant concentrations 41 3.10.1 Weight variation and thickness 41 3.10.2 Crushing strength, tensile strength and friability 42 3.10.3 Disintegration time 44 3.10.4 Drug dissolution 45 4. CONCLUSION 47 5. SUGGESTIONS FOR FURTHER WORK 48 REFERENCES 49 iv LIST OF TABLES Table 2.1: Tablet composition for disintegrant evaluation 15 Table 2.2 Tablet composition for dilution capacity evaluation 16 Table 3.1: Powder properties of dioscorea starches and starch 1500® 24 Table 3.2: Compaction properties of native dioscorea starch (NDS), ® acid modified dioscorea starch (AMDS) and Starch 1500 29 Table 3.3: Weight and thickness of paracetamol tablets formulated by direct compression method at different Paracetamol concentrations 36 Table 3.4: Tensile strength of spray dried NDS, spray dried AMDS ® Starch 1500 tablets at different paracetamol concentrations 38 Table 3.5: Weight and thickness of tablets formulated by wet granulation method at different disintegrant concentrations 41 Table 3.6: Tensile strength of paracetamol tablets formulated from NDS, ® AMDS and Starch 1500 at different disintegrant concentrations 44 v LIST OF FIGURES Figure 1.1: Chemical structure of (A) Linear amylose starch molecule and (B) branched Amylopectin starch molecule 1 Figure 1.2: Photo of dioscorea plant (A) and tuber in the garden (B) 3 Figure 2.1: Absorbance of paracetamol in phosphate buffer (pH 5.8) at 243 nm with 95% confidence bands for the mean; (r2 = 0.999) 14 Figure 3.1: Recovery yield of dioscorea starch after acid hydrolysis 19 Figure 3.2a: The X-ray diffraction patterns of native dioscorea starch 20 Figure 3.2b: The X-ray diffraction patterns of acid modified dioscorea starch 21 Figure 3.3a: The FTIR spectra of paracetamol 22 Figure 3.3b: The FTIR spectra of acid modified dioscorea starch 23 Figure 3.3c: The FTIR spectra of paracetamol & AMDS mixture 23 Figure 3.4: Swelling power of dioscorea starches (native and acid modified) ® and Starch 1500 at different temperatures 26 Figure 3.5: Solubility of dioscorea starches (native and acid modified) and ® Starch 1500 at different temperatures 27 Figure 3.6: Moisture sorption patterns of dioscorea starches ® (native and acid modified) and Starch 1500 28 ® Figure 3.7: Crushing strength of spray dried NDS, AMDS and Starch 1500 tablets at different concentration of magnesium stearate 32 ® Figure 3.8: Friability of spray dried NDS, AMDS and Starch 1500 tablets at different concentration of magnesium stearate 33 Figure 3.9: Tensile strength of spray dried NDS, spray dried AMDS and ® Starch 1500 tablets at different concentration of magnesium stearate 34 Figure 3.10: Disintegration time of spray dried NDS, spray dried AMDS and ® Starch 1500 tablets at different concentration of magnesium stearate 35 Figure 3.11: Crushing strength of tablets formulated from spray dried NDS, ® spray dried AMDS and Starch 1500 at different paracetamol concentrations 37 vi Figure 3.12: Friability of spray dried NDS, spray dried AMDS and ® Starch 1500 at different paracetamol concentrations 39 Figure 3.13: The disintegration time of tablets formulated from spray dried ® NDS, spray dried AMDS and Starch 1500 at different paracetamol concentrations 40 Figure 3.14: Dissolution profiles of spray dried NDS, spray dried AMDS & ® Starch 1500 at 20 & 50% paracetamol concentrations 41 Figure 3.15: The crushing strength of tablets formulated from NDS, AMDS ® and Starch 1500 at different concentrations of disintegrant 43 Figure 3.16: The friability of tablets formulated from NDS, AMDS and ® Starch 1500 at different concentrations of disintegrant 43 Figure 3.17: The disintegration time of tablets formulated from NDS, AMDS ® and Starch 1500 at different disintegrant concentrations 45 Figure 3.18: Dissolution profiles of paracetamol tablets at low (5% w/w) and high (12.5% w/w) disintegrant concentrations 46 vii ACRONYMS ANOVA: Analysis of Variance AMDS: Acid Modified Dioscorea Starch API: Active Pharmaceutical Ingredient BP: British Pharmacopoeia CL: Chain Length DP: Degree of Polymerization FTIR: Fourier Transform Infrared NC: Number of Chains NDS: Native Dioscorea Starch PVP: Polyvinylpyrrolidone SD: Standard Deviation SNNPR: South Nation Nationalities and People Regional state RH: Relative Humidity RPM: Revolution Per Minute USP/NF: United State Pharmacopoeia/National Formulary UV: Ultra Violet viii ABSTRACT Starch is one of the most important and flexible food ingredients possessing value added attributes for innumerable industrial applications. Dioscorea abyssinica (Fam. Dioscoreaceae) is a potential source of starch for large scale production in Ethiopia. Starch is usually modified either chemically or physically to augment its convenience for industrial use.
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