Applications of Polymers in Drug Delivery

Applications of Polymers in Drug Delivery

Author: Edited by Ambikanandan Misra and Aliasgar Shahiwala
ISBN 9781847358516 

Published: 2014
page 546
Use of polymers has become indispensable in the field of drug delivery. Polymers play a crucial role in modulating drug delivery to exploit maximum therapeutic benefits and have been fundamental in the successful development of several novel drug delivery systems that are now available.

This book provides details of the applications of polymeric drug delivery systems that will be of interest to researchers in industries and academia. It describes the development of polymeric systems ranging from the conventional dosage forms up to the most recent smart systems. The regulatory and intellectual property aspects, as well as the clinical applicability of polymeric drug delivery systems, are also discussed.

Each different drug delivery route is discussed in a separate chapter of the book. All major routes of drug delivery have been covered to provide the reader with a panoramic as well as an in-depth view of the developments in polymer-based drug delivery systems. Appendices are included which incorporate useful pharmaceutical properties of the polymers and important polymeric applications for various drug delivery routes.
1 Polymers in Drug Delivery Systems
1.1 Introduction
1.2 Fundamentals of a Polymeric Drug Delivery System
1.2.1 Factors That Affect Drug Release from Polymers
1.2.2 Mechanism of Controlled Release Temporal Controlled Systems Delayed Dissolution Diffusion Controlled Release from Monolithic/Matrix Systems Reservoir Type Systems Osmotic/Solvent Controlled Systems Swelling Controlled Environmental/Stimuli Responsive Systems Thermo-responsive Polymers pH-Responsive Polymers Dual Stimuli-Responsive Polymers Distribution Controlled Systems Biodegradable/Degradation and Erosion Controlled Systems
1.3 Polymer Delivery Systems
1.3.1 Oral Drug Delivery System Gastro Retentive Drug Delivery System Floating System Hydrodynamically Balanced Systems Bio/Mucoadhesive Systems Hydration-mediated Adhesion Swelling Systems Colon Specific Drug Delivery System pH Sensitive Systems Coating with pH Dependent Polymers Coating with pH Independent Biodegradable Polymers Time Controlled/Dependent System Pressure Controlled System Osmotically Controlled System Pulsatile Drug Delivery System Ion-exchange Based Drug Delivery System
1.3.2 Transdermal Drug Delivery System Classification of Transdermal Drug Delivery Reservoir Systems Drug-in-adhesive Systems Matrix-dispersion Systems Micro-reservoir Systems Polymers for Transdermal Drug Delivery System Natural Polymers Synthetic Polymers Pressure Sensitive Adhesives Backing Membrane Release Liner
1.3.3 Mucoadhesive Drug Delivery System Hydrophilic Polymers Hydrogels Thiolated Polymers Lectin-based Polymers
1.3.4 Ocular Drug Delivery System Polymers used in Conventional Ocular Delivery Liquid Dosage Forms Semi-solid Dosage Forms Polymers used in Ophthalmic Inserts/Films
1.3.5 Implant and Parenteral Drug Delivery System Surgical Implants Microspheres Bioadhesive Microspheres Floating Microspheres Polymeric Microspheres Biodegradable Polymeric Microspheres Synthetic Polymeric Microspheres Injectable In Situ Gel Thermoplastic Paste In Situ Crosslinking System In Situ Polymer Precipitation Thermally-induced Gelling
1.4 Recent Advancements in Polymer Architecture and Drug Delivery
1.4.1 Block Copolymers
1.4.2 Polymersomes
1.4.3 Hyperbranched Polymers
1.4.4 Graft Polymers
1.4.5 Star Polymers
1.4.6 Dendrimers
1.5 Recent Patent Trends in Polymeric Drug Delivery
1.6 Future Developments

2 Applications of Polymers in Buccal Drug Delivery
2.1 Introduction
2.1.1 Advantages of Buccal Drug Delivery
2.1.2 Disadvantages of Buccal Drug Delivery
2.2 Factors Affecting Bioadhesion in the Oral Cavity
2.2.1 Functional Groups2
2.2.2 Molecular Weight
2.2.3 Flexibility
2.2.4 Crosslinking Density
2.2.5 Charge
2.2.6 Concentration
2.2.7 Hydration (Swelling)
2.2.8 Environmental Factors
2.3 Buccal Polymeric Dosage Forms
2.3.1 Semi-solids
2.3.2 Solids Powder Dosage Forms Tablets Polymeric Films and Patches
2.4 Novel Carriers
2.5 Conclusions

3 Applications of Polymers in Gastric Drug Delivery
3.1 Introduction
3.2 Need for Gastric Retention
3.3 Benefits and Pitfalls
3.4 Gastrointestinal Tract
3.4.1 Anatomy of the Gastrointestinal Tract Mucus Layer
3.4.2 Basic Gastrointestinal Tract Physiology
3.5 Factors Affecting Gastric Retention
3.6 Polymers in Gastro Retentive Drug Delivery Systems
3.6.1 Cellulosic Hydrocolloids
3.6.2 Carbomers or Carbopol®
3.6.3 Xanthan Gum
3.6.4 Guar Gum
3.6.5 Chitosan
3.6.6 Eudragit® Polymers
3.6.7 Alginate Polymers
3.6.8 Lectin-based Polymers
3.6.9 Thiolated Polymers
3.6.10 Miscellaneous Polymers
3.7 Evaluation of Gastro Retentive Drug Delivery Systems
3.7.1 In Vitro Evaluation Floating Systems Swelling Systems
3.7.2 In Vitro Release
3.7.3 In Vivo Evaluation
3.8 Application of Polymers in Gastric Delivery Systems
3.8.1 Floating Drug Delivery System Effervescent Floating Dosage Forms Non-effervescent Floating Dosage Forms
3.8.2 Bioadhesive Drug Delivery System
3.8.3 Swelling and Expanding Delivery System
3.8.4 Combinational/Amalgamative Delivery System Bioadhesive and Floating Approach Swellable and Floating Approach Bioadhesion and Swelling Approach Bioadhesion and High-density Approach
3.8.5 Microparticulate Delivery System Microballoons/Hollow Microspheres Alginate Beads Floating Granules Super Porous Hydrogel Systems Raft Forming Systems
3.9 Conclusion
4 Applications of Polymers in Small Intestinal Drug Deliver
4.1 Introduction
4.1.1 Advantages of Polymer Coating
4.1.2 Benefit from Polymer Coatings with Sustained Release
4.2 Physiology of the Small Intestine
4.2.1 Mucosa of Small Intestine
4.2.2 Secretion into the Small Intestine Glands Pancreatic Secretion Biliary Secretions Digestion of the Food Nutrients 
4.2.3 pH of the Small Intestine
4.2.4 Gastrointestinal Motility
4.2.5 Transit of the Dosage Form through the Small Intestine
4.2.6 Drug Absorption through Small Intestine
4.2.7 Peyer’s Patch
4.3 Scope of Small Intestinal Drug Delivery
4.4 Polymers used in Small Intestinal Drug Delivery
4.4.1 Natural Polymers Chitosan Shellac Sodium Alginate
4.4.2 Synthetic Polymers Polyacrylic acid Derivatives (Carbomer) Cellulose Derivatives Cellulose Acetate Phthalate Hydroxypropyl Methyl Cellulose Phthalate Polyvinyl Acetate Phthalate Hydroxypropyl Methyl Cellulose Acetate Succinate Cellulose Acetate Trimelliate Polymethacrylates Polymethacrylic Acid-co-ethyl Acrylate as Aqueous Dispersion. Polymethacrylic Acid-co-ethyl Acrylate as Powder Polyethyl Acrylate-co-methyl Methacrylate-co-trimethylammonioethyl Methacrylate Chloride Polymethacrylic Acid-co-methyl Methacrylate Polymethacrylic Acid-co-methylmethacrylate Methacrylic Acid - Methyl Methacrylate Copolymer (1:2) Polymethacrylic Acid-co-methyl Methacrylate (1:2)
4.5 Benefits of Polymers in Small Intestinal Drug Delivery
4.5.1 Hydroxypropyl Methyl Cellulose Phthalate
4.5.2 Hydroxypropyl Methyl Cellulose Acetate Succinate.
4.5.3 Hydroxypropyl Methyl Cellulose Acetate Maleate.
4.5.4 Methacrylic Acid Polymers and Copolymers
4.5.5 Chitosan
4.5.6 Chitosan and Methacrylic Acid Polymer and Copolymers
4.5.7 Sodium Alginate
4.5.8 Thiolated Tamarind Seed Polysaccharide
4.6 Conclusion

5 Application of Polymers in Transdermal Drug Delivery
5.1 Introduction
5.2 Advantages of Drug Delivery via the Transdermal Route
5.3 Mechanism of Drug Absorption in Transdermal Drug Delivery
5.4 Factors Affecting Transdermal Permeation
5.4.1 Physicochemical Properties of Penetrant Molecules
5.4.2 Physicochemical Properties of the Drug Delivery
System Release Characteristics Composition of the Drug Delivery Systems Drug Permeation Enhancer
5.4.3 Physiological and Pathological Conditions of the Skin
5.5 Types of Transdermal Drug Delivery Systems
5.5.1 Formulation Aspects Matrix Systems Reservoir Systems Micro-reservoir Systems
5.5.2 Based on Release Mechanism Passive Transdermal Drug Delivery Systems. Active Transdermal Drug Delivery Systems
5.6 Role of Polymers in Transdermal Drug Delivery Systems
5.6.1 Matrix Formers Crosslinked Polyethylene Glycol Acrylic-acid Matrices Ethyl Cellulose and Polyvinyl Pyrrolidone Hydroxypropyl Methylcellulose Chitosan Ethyl Vinyl Acetate Copolymer Gum Copal Damar Batu Organogels
5.6.2 Rate-controlling Membrane Ethylene Vinyl Acetate Copolymer Polyethylene Polyurethane Crosslinked Sodium Alginate Copolymer of 2-Hydroxy-3- Phenoxypropylacrylate, 4-Hydroxybutyl Acrylate and Sec-Butyl Tiglate Polysulfone, Polyvinylidene Fluoride (Hydrophilic Membrane) Polytetrafluoroethylene (Hydrophobic Membrane) Crosslinked Polyvinyl Alcohol Cellulose Acetate Eudragit® Chitosan
5.6.3 Pressure Sensitive Adhesives Polyisobutylenes Silicones Acrylics Hot-melt Pressure Sensitive Adhesives Hydrogel Pressure Sensitive Adhesives Hydrophilic Pressure Sensitive Adhesives Polyurethanes
5.6.4 Backing Layer/Membranes
5.6.5 Release Liner
5.6.6 Polymers to Enhance Skin Permeation Penetration Enhancers Pulsed Delivery
5.7 Future Perspectives
5.8 Conclusion

6 Application of Polymers in Peyer’s Patch Targeting
6.1 Introduction
6.2 Peyer’s Patch Physiology, Structure, and Function
6.2.1 General Properties and Peyer’s Patch Distribution in Different Species
6.2.2 M Cell Structure and Function
6.3 Strategies for Achieving Effective Delivery to the Peyer’s Patch
6.3.1 General Principles of Peyer’s Patch Delivery
6.3.2 Effect of Particle Size on Peyer’s Patch
6.4 Peyer’s Patch Drug Delivery using Polymeric Carriers
6.4.1 Polylactide-co-glycolic Acid
6.4.2 Polylactic Acid
6.4.3 Poly-D,L-lactide-co-glycolide
6.4.4 Polystyrene
6.4.5 Chitosan
6.4.6 Other Polymer Carrier
6.5 Uptake of Particles by Peyer’s Patches
6.6 Targets for Peyer’s Patch Delivery
6.6.1 Lectin-mediated Targeting
6.6.2 Microbial Protein-mediated Targeting Yersinia Salmonella Cholera Toxin Virus Protein
6.6.3 Vitamin B12 Mediated Targeting
6.6.4 Non-Peptide Ligand Mediated Targeting
6.6.5 Peptide Ligand Mediated Targeting
6.6.6 Claudin-4 Mediated Targeting
6.6.7 Monoclonal Antibody Mediated Targeting
6.6.8 M Cell Homing Peptide Targeting
6.6.9 Immunoglobulin A Conjugates Targeting
6.7 Summary and Conclusions
7 Applications of Polymers in Colon Drug Delivery
7.1 Introduction
7.2 Anatomy of the Colon
7.3 Correlation between Physiological Factors and use of Polymers in Colon Drug Delivery Systems
7.3.1 The pH of the Gastrointestinal Tract
7.3.2 Gastrointestinal Transit Time
7.3.3 Colonic Motility
7.3.4 Colonic Microflora
7.3.5 Colonic Absorption
7.4 Advantages of Colon Drug Delivery Systems
7.5 Disadvantages of Colon Drug Delivery Systems
7.6 Polymers for Colon Drug Delivery Systems
7.6.1 Pectin
7.6.2 Guar Gum
7.6.3 Chitosan
7.6.4 Amylose
7.6.5 Inulin
7.6.6 Locust Bean Gum
7.6.7 Chondroitin Sulfate
7.6.8 Dextran
7.6.9 Alginates
7.6.10 Cyclodextrin
7.6.11 Eudragit®
7.6.12 Cellulose Ethers
7.6.13 Ethyl Cellulose
7.6.14 Polymers for Enteric Coating
7.6.15 Polyvinyl Alcohol
7.7 Application of Polymers in Colon Drug Delivery Systems
7.7.1 System Dependent on pH
7.7.2 System Dependent on Time Reservoir Systems with Rupturable Polymeric Coats Reservoir Systems with Erodible Polymeric Coats Reservoir Systems with Diffusive Polymeric Coats Capsular Systems with Release-controlling Polymeric Plugs Osmotic System
7.7.3 Bacterially Triggered System Prodrug Polysaccharide-based Matrix, Reservoirs and Hydrogels
7.7.4 Time- and pH-Dependent Systems
7.7.5 Pressure Controlled Delivery Systems
7.8 Conclusion

8 Applications of Polymers in Parenteral Drug Delivery
8.1 Introduction
8.2 Parenteral Route for Drug Delivery
8.2.1 Advantages of Parenteral Administration
8.2.2 Disadvantages of Parenteral Administration
8.3 In Vivo Distribution of Polymer
8.4 Biodegradation
8.4.1 Erosion
8.4.2 Degradation Processes Chemical and Enzymic Oxidation Chemical and Enzymic Hydrolysis
8.5 Polymers for Parenteral Delivery
8.5.1 Non-degradable Polymers
8.5.2 Biodegradable Polymers Synthetic Polymers Polyesters Polylactones Polyamino acids Polyphosphazenes Polyorthoesters Polyanhydrides Natural Polymers Collagen Gelatin Albumin Polysaccharides
8.6 Polymeric Drug Delivery Carriers
8.6.1 Polymeric Implants
8.6.2 Microparticles
8.6.3 Nanoparticles
8.6.4 Polymeric Micelles
8.6.5 Hydrogels
8.6.6 Polymer-drug Conjugates
8.7 Factors Influencing Polymeric Parenteral Delivery
8.7.1 Particle Size
8.7.2 Drug Loading
8.7.3 Porosity
8.7.4 Molecular Weight of the Polymer
8.7.5 Crystallinity
8.7.6 Hydrophobicity
8.7.7 Drug-polymer Interactions
8.7.8 Surface Properties: Charge and Modifications
8.8 Summary

9 Applications of Polymers in Rectal Drug Delivery
9.1 Introduction
9.2 Rectal Drug Delivery
9.2.1 Anatomy and Physiology of the Rectum
9.2.2 Absorption through the Rectum Mechanism of Absorption Factors Affecting Absorption
9.3 Polymers used in Rectal Dosage Forms
9.3.1 Solutions
9.3.2 Semi-solids/Hydrogels
9.3.3 Suppositories
9.3.4 In Situ Gels
9.4 Conclusion

10 Applications of Polymers in Vaginal Drug Delivery
10.1 Anatomy and Physiology of the Vagina
10.1.1 Vaginal pH
10.1.2 Vaginal Microflora
10.1.3 Cyclic Changes
10.1.4 Vaginal Blood Supply
10.2 The Vagina as a Site for Drug Delivery
10.3 Vaginal Dosage Forms
10.4 Polymers for Vaginal Drug Delivery
10.4.1 Polyacrylates
10.4.2 Chitosan
10.4.3 Cellulose Derivatives
10.4.4 Hyaluronic Acid Derivatives
10.4.5 Carrageenan
10.4.6 Polyethylene Glycols
10.4.7 Gelatin
10.4.8 Thiomers
10.4.9 Poloxamers
10.4.10 Pectin and Tragacanth
10.4.11 Sodium Alginate
10.4.12 Silicone Elastomers for Vaginal Rings
10.4.13 Thermoplastic Polymers for Vaginal Rings
10.4.14 Miscellaneous
10.5 Toxicological Evaluation
10.6 Conclusion

11 Application of Polymers in Nasal Drug Delivery
11.1 Introduction 379
11.2 Nasal Anatomy and Physiology
11.2.1 Nasal Vestibule
11.2.2 Atrium
11.2.3 Olfactory Region
11.2.4 Respiratory Region
11.2.5 Nasopharynx
11.3 Biological Barriers in Nasal Absorption
11.3.1 Mucus
11.3.2 Nasal Mucociliary Clearance
11.3.3 Enzymic Barrier
11.3.4 P-Glycoprotein Efflux Transporters
11.3.5 Physicochemical Characteristics of the Drug
11.4 Toxicity
11.5 General Considerations about Polymers used in Nasal Drug Delivery
11.5.1 Thermoresponsive Polymers
11.5.2 Polymers Sensitive to pH
11.5.3 Mucoadhesive Polymer
11.6 Polymers used in Nasal Drug Delivery
11.6.1 Cellulose Derivatives
11.6.2 Polyacrylates
11.6.3 Starch
11.6.4 Chitosan
11.6.5 Gelatin
11.6.6 Phospholipids
11.6.7 Poly(N-alkyl acrylamide)/Poly(N-isopropylacrylamide)
11.6.8 Poloxamer
11.6.9 Methylcellulose
11.6.10 Cyclodextrin
11.7 Applications of Polymers in Nasal Delivery
11.7.1 Local Therapeutic Agents
11.7.2 Genomics
11.7.3 Proteins and Peptides
11.7.4 Vaccines Features of the Nasal Mucosa for Immunisation
11.8 Conclusion
12 Application of Polymers in Lung Drug Delivery
12.1 Introduction
12.2 Anatomy and Physiology of Human Respiratory Tract
12.3 Barriers in Pulmonary Delivery
12.4 Polymers for Pulmonary Drug Delivery
12.4.1 Natural Polymers Chitosan Gelatin Hyaluronic Acid Dextran Albumin
12.4.2 Synthetic Polymers Poly(D,L-lactide-co-glycolide) Polylactic Acid Poly(?-caprolactone) Acrylic Acid Derivatives Diketopiperazine Derivatives Polyethylene Glycol Conjugates
12.4.3 Miscellaneous Polymers
12.5 Conclusion
12.6 Future Directions

13 Applications of Polymers in Ocular Drug Delivery
13. 1 Introduction
13.2 Barriers to Restrict Intraocular Drug Transport
13.3 Drug Delivery Systems to the Anterior Segment of the Eye
13.3.1 Viscous Systems
13.3.2 In Situ Gelling Systems Temperature Induced In Situ Gelling Systems Poloxamers Xyloglucan Methyl Cellulose Ionic Strength Induced In Situ Gelling Systems Gellan Gum Alginates Carrageenan pH Induced In Situ Gelling Systems Carbomers (Polyacrylic Acid) Pseudolatexes
13.3.3 Mucoadhesive Gels
13.3.4 Polymeric Inserts/Discs
13.3.5 Contact Lenses Conventional Contact Lens Absorbed with Drugs Molecularly Imprinted Polymeric Hydrogels Drug-polymer Films Integrated with Contact Lenses Drugs in Colloidal Structure Dispersed in the Lens
13.3.6 Scleral Lens Delivery Systems
13.3.7 Punctal Plug Delivery Systems
13.4 Polymeric Drug Delivery Systems for the Posterior Segment of the Eye
13.4.1 Intravitreal Implants
13.4.2 Particulate Systems (Nanocarriers)
13.5 Conclusion
Appendix 1
Appendix 2