ABSTRACT

Microsphere drug delivery systems are used to protect sensitive drugs from enzymatic degradation in the body, for controlled release and tissue targeting of the drug of interest. Starch and products derived from starch modification, are increasingly gaining acceptance in microsphere drug delivery. They are less expensive, non-toxic, readily available, bio-compatible and bio-degradable. The aim of the study was to formulate sustained release pantoprazole microspheres and enteric-coated tablets using MPS. The specific objectives of the study were (i) modification of MPS by cross-linking with glutaraldehyde, (ii) formulation of pantoprazole microspheres and tablets (iii) evaluation of the entrapment efficiency, particle size, mucoadhesive, swelling and in vitrorelease properties of the microspheres and (iv) evaluation of the tablet properties formulated.

MPS was extracted from the dried, pulverized endosperm of the dehulled seed of Mucuna pruriens utilislegume. The phytochemical analyses were performed on powdered MPS samples extracted. The samples were processed and the powder properties determined by standard Pharmacopoeial methods. MPS powder properties were compared with those of maize starch (MS) and cassava starch (CS). MPS was modified by heat treatment at 67.5 0C and used to prepare MPS flakes. The flakes were used to prepare MPS microspheres by emulsion cross- linking using glutaraldehyde as the cross-linking agent. Cross-linking time was varied between 10-180 min and the MPS microspheres prepared were characterized for particle size, swelling index and mucoadhesion. Photomicrographs of the MPS microspheres prepared were obtained. The MPS microspheres were loaded with pantoprazole and evaluated for mean particle size, trapping efficiency, mucoadhesion, and drug release profiles in both Simulated Gastric Fluid (SGF, pH=1.2) and Simulated Intestinal Fluid (SIF, pH=7.2). The pantoprazole microspheres were tabletted by the wet granulation method and tablet properties evaluated included: assay for pantoprazole content, weight uniformity, hardness, friability, disintegration and dissolution. Pantoprazole release in SGF and SIF were performed in a dissolution apparatus, using the basket type method and the content was assayedspectrophotometrically at 278 nm and 289 nm respectively. Pantoprazole release from the tablet formulations was fitted to the Korsmeyer- Peppas and Higuchi’sdiffusion model equations to elucidate and interprete drug release mechanism. Data analyses were performed by both descriptive and inferential statistics. The inferential analysis was done using GraphPadInStat Demo.

Phytochemical analyses of Mucuna pruriens utilis showed the presence of alkaloids, flavonoids, saponins, carbohydrates, resins and protein. Fat, oil, reducing sugar, tannins, and steroids were not detected. MPS microspheres cross-linked for 120 min had the highest entrapment efficiency of 81.3±1.40 % compared to an entrapment efficiency of 56.1±1.40 % for those cross-linked for 10 min only. Pantoprazole release from the microspheres was higher in SIF than in SGF. The release exhibited the triphasic pattern typical of microspheres. Representative plots of the Higuchi and Korsmeyers-Peppasequation for the release of pantoprazole in both SIF and SGF showed that the mechanism of drug release from the microspheres was complex and involved drug diffusion, desorption and surface erosion. The release mechanism obtained for microspheres cross-linked for 30 and 90 min in SGF and, cross-linked for 20, 30, 150 and 180 min in SIF, depicted non-Fickian(anomalous) diffusion model (0.43

TABLE OF CONTENTS

Title page ....i 

Certification ...ii 

Dedication ...iii 

Acknowledgement....iv 

Table of Content.v 

List of Figures ...ix 

List of Tables x 

List of Appendices.xi 

Abstract xii

Chapter 1 Introduction

1.1 Starch: Definition, Etymology and Source....1

1.2 Production and Purification of Starch...2

1.3 Applications of starch...2

1.3.1 Starch as source of food.3

1.3.2 Pharmaceutical Application of Starch...3

1.3.3 Miscellaneous application ....4

1.4 Test for Starch5

1.5 Starch Modification5

1.5.1 Chemical modification...7

1.5.2 Physical modification ...8

1.5.3 Enzymatic modification.8

1.5.4 Pregelatinization of Starch...11

1.6 Mucuna..11

1.6.1 Common species of Mucuna.12

1.6.2 Taxonomy of Mucuna pruriens Linn...15

1.6.3 Description of Mucuna pruriens....15

1.6.4 Traditional uses of M. pruriens Linn. ...16

1.7 Cross-Linking 17

1.7.1 Methods of Cross-linking....18

1.7.2 Chemical Cross-linkers.18

1.7.3 Factors Affecting Cross-linking...18

1.7.4 Cross-linking Agent.....19

1.7.5 Glutaraldehyde.....19

1.8 Chemistry and Pharmacological Profile of Pantoprazole ...20

1.9 Microspheres- A Drug Delivery System.....22

1.9.1 Advantages of Microsphere as a drug delivery system23

1.9.2 Disadvantages of Microsphere as a drug delivery system...24

1.9.3 Formulations of Microspheres.....24

1.9.4 Methods of preparation of Microspheres24

1.9.4.1 Solvent Evaporation Technique...24

1.9.4.2 Emulsion Cross-link Method-..25

1.9.4.3 ComplexCoacervation Method .....25

1.9.5 Mechanism of Drug Loading...26

1.9.6 Drug Release from Microspheres....26

1.9.7 Mechanism and Kinetics of Drug Release28

1.10. Tablet Component and Excipients...29

1.10.1 Methods of Tablet Production..29

1.10.2 Wet Granulation30

1.10.2.1 Important steps involved in the wet granulation30

1.10.2.2 Limitation of wet granulation....30

1.10.2.3 Special wet granulation techniques...31 

10.2.3.1 High shear mixture granulation.....31

1.10.2.3.2 Fluid bed granulation ...31

1.10.2.3.3 Extrusion and Spheronization 31

1.10.2.3.4 Spray drying granulation32

1.10.3. Dry granulation .32

1.10.3.1 Steps in dry granulation ...33 

1.10.3.2 Slugging process...33 

1.10.3.3 Roller compaction..34

1.10.3.4 Formulation for dry granulation ....34

1.10.4 Direct Compression.34

1.10.5 Advances in Granulation.35

1.10.5.1 Steam Granulation...35

1.10.5.2 Melt Granulation / Thermoplastic Granulation

1.10.5.3 Moisture Activated Dry Granulation (MADG).....36 

1.10.5.4 Moist Granulation Technique (MGT)...36

1.10.5.5 Thermal Adhesion Granulation Process (TAGP) ..36

1.10.5.6 Foam Granulation...36

1.10.6 Equipment used in Tablet Production....37

1.10.7 Good Manufacturing Practices (GMP) For Pharmaceutical Products-...37

1.11 Aims and Objectives of the Study..38

Chapter 2 Experimental 

2.0 Materials and Methods..39 

2.1 Materials 

2.1.1 Equipment....39 

2.2 Methods 

2.2.1 Processing of M. pruriens utilis ..40 

2.2.2 Phytochemical Analysis-40

2.2.2.1 Test for Alkaloids..40

2.2.2.2 Test for Carbohydrates..40

2.2.2.3 Test for Reducing Sugar41

2.2.2.4 Test for Glycosides41

2.2.2.5 Test for Tannins....41

2.2.2.6 Test for Saponin...41

2.2.2.7 Test for Starch ...42

2.2.2.8 Test for Proteins...42

2.2.2.9 Test for Flavonoids42

2.2.2.10 Test for Resins ....43

2.2.2.11 Test for Steriods and Terpenoids...43 

2.2.2.12 Test for Acidic Compounds43 

2.2.2.13 Test for Fats and Oils.44 

2.2.3 Removal of Non-starchy materials...44

2.2.4 Powder Characteristics of M. pruriens.....44

2.2.4.1 Bulk Density44

2.2.4.2 Tapped Density....44

2.2.4.3 Angle of Repose...44

2.2.4.4 Flow Rate.....45

2.2.4.5 Ash Value....45

2.2.4.6 Hydration Capacity.....46

2.2.4.7 Moisture Content-46

2.2.4.8 Melting point or Gelatinization Temperature...../46

2.2.4.9 Preparation of Pregelatinized M. pruriens starch.46

2.2.4.9.1 Preparation of M. pruriens flakes 46

2.2.4.9.2 Preparation of Microspheres and drug-loading...46

2.2.5 Preparation of Buffer Solution.....47

2.2.6 Preparation of Simulated Intestinal Fluid (SIF)....47

2.2.7 Preparation of Simulated Gastric Fluid (SGF).....47

2.2.8 Determination of Standard Calibration Curve (Beers Plot).........47

2.2.9 Characterization of Microspheres..............51

2.2.9.1 Photomicrograph of Microspheres.............51

2.2.9.2 Determination of absolute drug content of drug loaded Microspheres-...................51

2.2.9.3 Entrapment efficiency...;51

2.2.9.4 Determination of Particles Size.................52

2.2.9.5 Swelling studies.........52

2.2.9.6 Evaluation of mucoadhessive property.........52

2.2.9.7 In Vitro Release Study of Drug-loaded Microspheres................53

2.2.10 Enteric Coating of Pantoprazole Tablets.....53 

2.2.11 Tablet Properties of M. pruriens Starch...57

2.2.11.1 Hardness Test-..57 

2.2.11.2 Friability Test...57

2.2.11.3 Disintegration Test-..57 

2.2.11.4Weight Uniformity Test....57

2.2.11.5 In vitro Drug Release 58

2.2.11.6 Assay of Active Ingredients58 Chapter 3

Result and Discussion

3.0 Phytochemical Constituents 

3.1 Comparison of the Physical properties of some starches...61 

3.2 Physical Properties of Pantoprazole Tablets ....73

Chapter 4

Summary and Conclusion and Recommendation

4.1 Summary of Results..82

4.2 Conclusion

4.3 Recommendation.....83

References 

Appendices