Unit 1 Novel drug delivery Polymers.pptx

Polymers

1. POLYMERS Ms. Shubhangi B Khade Assistant professor Department of pharmaceutics Sanjivani College of Pharmaceutical education & research(Autonomous) Kopargaon, M aharashtra

2. CONTENTS Introduction Classification of polymers Properties of polymers Advantages of polymers Application of polymers 2

3. Introduction POLYMER Polymer is a long molecule made up from lots of small molecules called monomers . The word polymer comes from Greek words poly means many and mer means parts 3

4. Most polymers are hydrocarbons– i.e. made up of H and C Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function 4

5. CHARACTERISTICS OF IDEAL POLYMER Low Density. Low coefficient of friction. Good corrosion resistance. Good mold ability. Excellent surface finish can be obtained. Can be produced with close dimensional tolerances. Economical. Poor tensile strength. Low mechanical properties. Poor temperature resistance. Can be produced transparent or in different colours 5

6. Classification of Polymers Based on Source Natural polymers . Ex. Cellulose , Starch , Rubber, Albumin, chitosan, dextrin,etc B. Semi-synthetic polymers. Ex. Cellulose derivatives -Cellulose acetate (Rayon) c. Synthesis polymers. Ex Nylon, Polythene, Polyester 6

7. CLASSIFICATION BASED ON STRUCTURE Linear polymers - the smallest repeating unit arrange in straight line path is known as Linear polymer. Ex. PVC Branched chain polymers - contain linear chains having some branches. Ex. low density polymer Cross linked chain polymers - formed from bifunctional and tri-functional monomers and contain strong covalent bonds. Ex. Bakelite 7

8. CLASSIFICATION BASED ON MOLECULAR FORCE Thermoplastic Polymers - These are linear or slightly branched long chain polymers, which can be softened on heating & reversibly hardened on cooling repeatedly. Ex. polyvinyl chloride Thermosetting polymers - Initial Mixture of Reactive, Low Molar Mass Compounds Reacts Upon Heating In The Mold To Form An Insoluble,Infusible Network. Ex. Bakelite .Bakelite Is Formed of Phenol And Formaldehyde Polymerization. 8

9. Classification Based on Monomers Homopolymer - In this type, a single type of monomer unit is present . Ex. Polystyrene Copolymer- It consists of different type of monomer units . Ex. Styrene Butadiene Classification based on backbone structure/presence of carbon chain Organic Polymers: backbone chain is essentially made up of C atoms. Ex. Polyethylene, polypropylene Inorganic Polymers: backbone chain is made up of hetero chain other than Carbon atom. Ex. Polyethylene oxide, polypropylene oxide 9

10. Classification of Synthetic polymers Biodegradable polymer : Lactide / Glycolide PolyAnhydrides Polycaprolactones Poly orthoesters Polyphosphazene Pseudo Poly amino acids Natural Polymers Non biodegradable polymer 10

11. Lactide / Glycolide polymers They are biocompatible, exhibit predictable bio degradation kinetics . Ease of fabrication and have regulatory approval. Homo and copolymers are synthesized by ring opening melt condensation of a cyclic dimer, lactide and glycolide . Have advantages of versatality , performance properties, hence shows wide applications in CDDS. Shows wide range of hydrophilicity which makes them versatile in designing CDDS. Undergo bio degradation by bulk erosion . They are cleaved by hydrolysis to the monomeric acids and eliminated through Krebs cycle, primarily as carbon oxide and in urine . 11

12. One of the reasons for the popularity is ease of fabrication into various types i . e microparticles , implants, fibres . Etc. Microspheres and microcapsules are generally prepared by. Solvent evaporation method Phase separation method Fluidised bed coating 12

13. Poly Anhydrides They were investigated in an attempt to introduce polymeric systems which can degrade only from the surface to maximize control over the release process . They are promising candidates which can erode in a controlled manner. Approaches for synthesizing poly anhydrides include melt polycondensation , dehydrochlorination and dehydrative coupling. The matrices were formulated by either by compression or by injection molding . Microspheres of poly anhydrides were developed by hot melt process or by solvent removal method. Poly anhydrides compacts containing many drugs like corticosteroids have been fabricated by trituration and compression , and also by co dissolving and solvent technique. 13

14. Poly caprolactones and its co polymers The identity of poly caprolactones as a biodegradable polymer emerged as a result of extensive work by union carbide to identify synthetic polymers degraded by microorganis ,. Polycaprolactones and its derivatives are assessed to be well suited for controlled delivery due to high permeability to many drugs, and freedom from toxicity. Has exceptional ability to form compatible blends with variety of other polymers. It is manufactured by oxidation of cyclohexanone with peracetic acid. Derivatives are most convinently prepared by Bayer Villiger peroxidation of the corresponding ketone. Films of polycaprolactones are generally prepared by casting the common solution of the polymer and the drug. Many drugs like tetracycline , 5FU have been investigated using PCL copolymers including to peroidental pockets,. 14

15. Poly orthoesters They are one of the polymers that contain acid labile linkages to their backbone. The hydrolysis of such polymers can be predominantly confined to outer surface and the resultant surface erosion allows excellent control of the release kinetic of the incorporated therapeutic agent. They are prepared by trans esterification. The polymer has been investigated for usage in development of various formulations like implants and oral delivery systems. Ex. Implants containing Levonorgestrel . 15

16. Poly Phosphazenes Polyphosphazenes are an example of a polymer where hydrolytic stability / instability is determined not by change in the backbone structure but by change in side groups attached to macromolecular backbone. Poly phosphazenes and its derivatives have been used in fabrication of matrix containing. Melphalan In addition drugs containing carboxylic acid groups could also be linked to polyphosphazenes by amide linkage to prepare CDDS prodrug . Derivatives also been investigated for use as hydrogels. 16

17. Pseudo Poly amino Acids Are derived from simple nutrient amino acid They are prepared by linking amino acids by bonds other than amide bonds and are reported useful in CDDS. 17

18. Natural Polymers Natural polymers remains attraction because they are natural products of living organism , readily available,relatively inexpensive and capable of multitude of chemical modifications. Majority investigations as matrices is centred on proteins, i.e collagen, gelatin, and albumin and polysaccharides i.e starch, dextran Most protein based DDS are formulated as solid crosslined microspheres. Collagen has been fabricated as films, fibres , sponges, absorbable sutures, sponge wound dressings Polysaccharides as microspheres. Hyaluronic acid found in highest conc in soft connective tissues so mainly used in ophthalmic preparations. 18

19. Polymers as Biomaterials A range of materials have been employed to control the release of drugs and other active agents. The earliest of these polymers were originally intended for other, nonbiological uses, and were selected because of their desirable physical properties, for example : Poly(urethanes) for elasticity. Poly( siloxanes ) or silicones for insulating ability. Poly(methyl methacrylate) for physical strength and transparency. Poly(vinyl alcohol) for hydrophilicity and strength. Poly(ethylene) for toughness and lack of swelling. Poly(vinyl pyrrolidone ) for suspension capabilities 19

20. To be successfully used in controlled drug delivery formulations, a material must be chemically inert and free of leachable impurities. It must also have an appropriate physical structure, with minimal undesired aging, and be readily processable . Some of the materials that are currently being used for controlled drug delivery include Poly(2-hydroxy ethyl methacrylate) Poly(N-vinyl pyrrolidone ). Poly(methyl methacrylate). Poly(vinyl alcohol). Poly(acrylic acid). Polyacrylamide. Poly(ethylene-co-vinyl acetate). Poly(ethylene glycol). Poly( methacrylic acid). 20

21. Factors Affecting Biodegradation Of Polymers •Chemical structure and composition. •Distribution of repeat units in multimers . •Presence of ionic group. • Configuration structure. •Presence or unexpected units or chain defects. •Molecular weight •Molecular weight distribution. 21

22. •Morphology- amorphous/ semi crystalline,microstructures , residual stresses. •Presence of low molecular weight compounds. •Processing condition. •Annealing. •Sterilization process. •Shape. •Site of implantation. •Adsorbed and absorbed compounds like water, lipids and ions. •Physicochemical factors like ion exchange, ionic strength and pH. •Physical factors like shape and size changes, variations of diffusion coefficients, mechanical stresses , stress and solvent induced cracking. •Mechanism of hydrolysis 22

23. Applications APPLICATIONS OF POLYMERS IN SOLID DOSAGE FORMS IN TABLETS Polymers like methyl cellulose, hydroxyl ethyl cellulose, hydroxyl ethyl methyl cellulose are used as binders. Polymers likecarboxyl methyl cellulose sodium is used as disintegrating agent . Polymers like all the cellulose derivative are used as film coating materials. Polymers like cellulose acetate phthalate , hydroxyl propyl methyl cellulose phthalate, polyvinyl acetate phthalate are used as enteric coating material. INCAPSULES Gelatin, a natural polymer which is the major ingredient in the manufacturing of capsules 23

24. THANK YOU 24