Biodegradable polymers

Biodegradable polymers used in controlled drug delivery system

1. BIODEGRADABLE POLYMER Presented By Miss.Prerana Husukale Roll no.03 M.pharm-I sem-I Government College Of Pharmacy, Karad

2. INTRODUCTION Polymers , also known as Macromolecules, are very large molecules consisting of many repeating units and are formed by a process called polymerization, which links together small molecules known as monomers. The term Polymer was coined in 1833 by Johns Jacob Berzelius. Polymer, Greek: polus- many,much;meros- parts.

3. Definition : Biodegradable polymers are defined as special class of polymer that break down after its intended purpose by bacterial decomposition process to result in natural byproducts such as water,Co2,biomass & salts. Another way to define is polymers with hydrolysable backbones are susceptible to biodegradation under particular conditions. This polymers have properties of degrading in biological fluids with progressive release of dissolved or dispersed drug. The most promising area of application involves drug composites which are implanted, injected or inserted.

4. Why bio-degradable polymers developed? Field expanded from research to applications,it was recognized that surgical removal of a drug depleted delivery system was difficult and non removal may pose toxicological problems. Diffusion controlled delivery systems though are excellent means of achieving predetermined rates of drug delivery,it is limited by the polymer permeability and the characteristics of drug.

5. Basic approches governing the design of DDS containing biodegradable polymers Erosion of polymer surface with concomitant release of physically entrapped drug. Cleavage of covalent bond between the polymer & drug occuring in two polymer bulk or at the surfaces followed by diffusional drug loss. Diffusion controlled release of the physically entrapped drug,with bio –absorption of the polymer delayed until after drug depletion.

6. Classification Of Biodegradable Polymers

7. Ideal characteristics of biodegradable polymers; They should be biocompatible – [ shape, surface & leachable} They should be bio absorbable –[ degradability profile, reabsorption of degradation products] They should be bi functional- [ physical, mechanical & biological] They should be stable – [processing, sterilization & storage]

8. Enzymatic/ chemical degradation: It mediated by water,enzymes, microbes. Involves cleavage of crosslink, transformation of side chain, cleavage of backbone; Hydrolysis: 1. Bulk erosion – Degradation takes place throughout the whole of the sample. e.g. Polylactic acid[PLA], Polyglycolic acid[PGA] 2. Surface erosion – Sample is eroded from the surface. e.g. Polyanhydries, Polyorthoesters.

9. Bulk erosion Surface erosion

10. Factors Affecting Bio-Degradation Morphological factors : Shape & Size Chemical factors : Chemical structure & composition, Presence of ionic group and configuration structure, Molecular weight Physical factors : Processing condition, Sterilization process.

11. Applications of Biodegradable polymer Polymer system for gene therapy. Biodegradable polymer for ocular,tissue engineering,vascular,orthopedic,skin adhesive & surgical glues. Therapeutic agent such as antitumor,antipsychotic,aninflammatory agent. Many biomedical materials are made of polymers.

12. Lupron Depot It contains the following: leuprolide acetate 7.5 mg. Nonmedicinal ingredients: D,L-lacticglycolic acids copolymer(66.2 mg ), When mixed with diluent, the sterile lyophilized microspheres become a suspension, which is intended as an i.m. injection Lupron Depot: 7.5 mg (1-month Slow Release)

13. Reference N.K.Jain,Contrlloed & Novel Drug Delivery,CBS publications & Distributors, New Delhi, first edition-27. http:// www.ijper.org/PDFs/Jan2006.pdf . Marcel In; A Handbook of Pharmaceutical Controlled Release Dekker publication ,99-863. www.biodegradable polymer.wikipedia