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BIODEGRADABLE POLYMERS Prepared by : Mr. Sagar L. Vekariya Guided by : Mr. Tejas sarasiya Babaria Institute of Pharmacy, Varnama Vadodara .


Introduction Classification of BDP Different mechanism of degradation Factor affecting degradation Factors that accelerate polymer degradation Methods for studying degradation of polymer Medical application content


Polymer : A Polymer is a substance composed of molecules with a large molecular mass of repeating structural units or monomers connected by covalent chemical bonds. Main purposes of using Polymers in Pharmaceutical field : improve drug stability Controlled and sustained release formulations Sites specific drug delivery Retard the unwanted characteristics of drugs like Taste, odor,etc . Novel drug delivery systems Introduction


These polymers comprised of monomers linked to one another through functional groups and have unstable linkages in the backbone They are biologically degraded or eroded by enzymes introduced in vivo or surrounding living cells or non enzymatic process in to oligomers . Why Would we Like a Material to Degrade in the Body ? Do not require a second surgery for removal Avoid stress shielding Offer tremendous potential as the basis for controlled drug delivery BIODEGRADABLE POLYMER

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Other advantages : Less toxicity problems as compared to non-biodegradable polymers The system would be biocompatible would least or not exhibit dose dumping at any time and polymer would retain its characteristics until after depletion of the drug. Disadvantages : Sometimes dose domping A “burst effect” or high initial drug release Degradable systems which are administered by injection of a particulate form are non- retrivable


Based on origin : Natural origin : Collagen, Albumin, Casein, etc. semi-synthetic polymers : Gelatin, Dextran , Chitin, Alginate, Chitosan , etc. Synthetic polymers : Aliphatic polyesters : PGA, PLA,PCL, etc. Polyphosphoesters , polyanhydrieds , polyphosphozenes , polyaminoacids Based on enviornmental factors : Thermosensitive polymer : Polyacrylamide , etc. Electrically and chemically controlled : Poly( pyrrole ), collagen, etc pH sensitive polymer : poly (2-ethylacrylic acid), etc. CLASSIFICATION of BDP

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III. Miscellaneous polymer employed in drug delivery devices : Polymeric phospholipids Polyethyleneamine Polyamidoamine Polyethylene glycol DIFFERENT MECHANISMS OF DEGRADATION : Chemical Degradation Physical Degradation Enzymatic Degradation

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1. Chemical degradation : Chemical changes occurs in polymers which includes cleavage of covalent bonds, hydrolysis, ionization or protonation either along the back bone or side chains of polymers. Chemical degradation leads to the change in molecular weight or solubility of polymer.

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Hemiacetal : Ether Nitrile Phosphonate Polycyanocrylate O C C C C C OH OH OH OH OH OH C C C C OH OH OH OH H 2 O + C==O H H 2 O

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2. Physical Degradation : (A) Bulk-eroding system ( PLA,PGA,PLGA, PCL ) Degradation takes place throughout the whole of the polymer matrix. Loss of physical integrity. Ingress of water is faster than the rate of degradation (B) Surface-eroding system ( poly( ortho )esters and polyanhydrides ) Eroded from the surface Physical integrity maintained Mass loss is faster than the ingress of water into the bulk

Factors Affecting Degradation:

Factors Affecting Degradation Chemical Structure and Chemical Composition Distribution of Repeat Units in Multimers Molecular Weight Polydispersity Presence of Low Mw Compounds (monomer, oligomers , solvents, plasticizers, etc) Presence of Ionic Groups Presence of Chain Defects Presence of Unexpected Units Configurational Structure Morphology ( crystallinity , presence of microstructure, orientation and residue stress) Processing methods & Conditions Method of Sterilization Annealing Storage History Site of Implantation Absorbed Compounds Physiochemical Factors (shape, size) Mechanism of Hydrolysis (enzymes vs water)

Factors That Accelerate Polymer Degradation :

More hydrophilic backbone. More hydrophilic endgroups . More reactive hydrolytic groups in the backbone. Less crystallinity . More porosity. Smaller device size. Factors That Accelerate Polymer Degradation

Methods of Studying Polymer Degradation:

Morphological changes (swelling, deformation, bubbling, disappearance…) Weight lose Thermal behavior changes Differential Scanning Calorimetry (DSC) Molecular weight changes Dilute solution viscosity Size exclusion chromatograpgy(SEC) Gel permeation chromatography(GPC) MALDI mass spectroscopy Change in chemistry Infared spectroscopy (IR) Nuclear Magnetic Resonance Spectroscopy (NMR) TOF-SIMS Methods of Studying Polymer Degradation

Medical Applications of Biodegradable Polymers:

Wound management Sutures Staples Clips Adhesives Surgical meshes Orthopedic devices Pins Rods Screws Tacks Ligaments Dental applications Guided tissue regeneration Membrane Void filler following tooth extraction Cardiovascular applications Stents Intestinal applications Anastomosis rings Controlled Drug delivery system Tissue engineering Medical Applications of Biodegradable Polymers

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Polymers Their applications Collagen In Wound repairing Chitosan gelling agent Dextran Plasma volume expander Lectins as mucoadhesive Cyclodextrins,guar-gum,pectin,dextran,inulin Delivery of drug to colon Poly–e-caprolactone Microsphere,implants Some Individual applications of Biodegradable polymers

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17 PLA,PLGA Exepient for injectible drugs PLA+Doxicyclin hyclate –periodontal disease PLGA+Growth hormone---growth deficiency PLA+Bone morphogenic protein----in Bone tissue engineering PLA+Leuprolide Acetate ----in prostate cancer Rosin As a adhesive in TDDS Polyurathanes Synthetic skin (synthaderm) Lyofoam In chromatography as Dextran Gel

Uses of polymers:

18 Uses of polymers




Pal O.P. Malviya R.,Bansal V.,Sharma P.K., Rosin an important polymer for drug delivery”,”international journal of pharmaceutical sciences”,volume-3,issue-1,july-aug-2010,article 007, Jain N.K.,”Pharmaceutical Product Development”,First edition,CBS publication,P.N.585-621. polymers Biodegradable %20Materials.ppt Biodegradable polymers as Drug Delivery system, edited by Mark Chasin , Robert Langer Volume 45 Controlled Drug Delivery by S.P.Vyas , page no- 97-155 Biodegradable polymers as biomaterials - Lakshmi S. Naira, Cato T. Laurencin Gelatin as a delivery vehicle for the controlled release of bioactive molecules- Simon Young , Mark Wong , Yasuhiko Tabata , Antonios G. Mikos -- Journal of Controlled Release 109 (2005) 256– 274 Polymers in drug delivery - Omathanu Pillai and Ramesh Panchagnula Department of Pharmaceutics, National Institute of Pharmaceutical Education & Research (NIPER) Polymeric biomaterial-L. G. GRIFFITH, Massachusetts Institute of Technology, Acta mater. 48 (2000) 263±277 Rationalizing the design of polymeric biomaterials- Nela Angelova and David Hunkeler 20 REFERENCES

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