The document discusses biodegradable polymers. It defines biodegradable polymers as polymers that can be broken down into biologically acceptable molecules via normal metabolic pathways. The ideal characteristics of biodegradable polymers include biocompatibility and biodegradability. The document outlines various factors that influence polymer degradation behavior and mechanisms. It also describes common medical applications of biodegradable polymers like sutures, drug delivery systems, and tissue engineering. The document provides examples of natural biodegradable polymers like collagen and gelatin as well as synthetic polymers like polylactic acid. In conclusion, biodegradable polymers show promise for advanced drug delivery but more research is needed to address issues like sensitivity to processing.

1. Prepared by:
Malay N. Jivani
M. pHarm sem 1. (ceutics)
Sub : PFD
BIODEGRADABLE POLYMERS
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2. CONTENTS:
 Introduction To Polymers
 Definition and Ideal Characteristics of biodegradable
polymers
 Factors Influence the Degradation Behavior
 Degradation Mechanisms
 Methods of Studying Polymer Degradation
 General Medical Applications of Biodegradable Polymers
 Classification of biodegradable polymers
 Advantages of biodegradable polymers
 Biodegradable polymer in Advanced Drug Delivery
 Conclusion
 References
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3. INTRODUCTION
 Polymer Polymers are defined as very large
molecules consisting of many repeating units & are
formed by a processes called polymerization , which
links together smaller molecules known as
monomers. Monomers can be linked together in
various ways to give Linear Branched cross linked
polymers
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4. Based on biodegradability polymers are classified as:
 Biodegradable polymers
eg : collagen, poly glycolic acid etc.,
 Non biodegradable polymers
eg : poly vinyl chloride, polyethylene etc
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5. BIODEGRADABLE POLYMER :
 Definition :
Defined as polymers comprised of monomers
linked to one another through functional
groups and have unstable links in the
backbone . Broken down into biologically
acceptable molecules that are metabolized
and removed from the body via normal
metabolic pathways .
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6. IDEAL CHARACTERISTICS:
 Inert Permeability
 Biodegradability
 Bio- compatilibility
 Tensile strength
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7. Factors Influence the Degradation Behavior
 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)
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8. Degradation Mechanisms
 Enzymatic degradation
 Hydrolysis
(depend on main chain structure: anhydride > ester
> carbonate)
 Homogenous degradation
 Heterogenous degradation
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9. Degradation can be divided into 4 steps:
 Water sorption
 Reduction of mechanical properties (modulus &
strength)
 Reduction of molar mass
 Weight loss
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10. Degradation Schemes
 Surface erosion (poly(ortho)esters and
polyanhydrides)
 Sample is eroded from the surface
 Mass loss is faster than the ingress of water into the bulk
 Bulk degradation (PLA,PGA,PLGA, PCL)
 Degradation takes place throughout the whole of the sample
 Ingress of water is faster than the rate of degradation
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11. 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.
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12. 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
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13. General 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
 Drug delivery system
 Tissue engineering
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14. Why Would a Medical Practitioner 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
BONE+PLATE
BONE PLATE
Time
MechanicalStrength
Degradable Polymer
Plate
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15. Biodegradable Polymers Used for Medical Applications
 Natural polymers
 Fibrin
 Collagen
• Chitosan
 Gelatin
 Hyaluronan
 Synthetic polymers
 PLA, PGA, PLGA, PCL, Polyorthoesters …
 Poly(dioxanone)
 Poly(anhydrides)
 Poly(trimethylene carbonate)
 Polyphosphazenes
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16. CLASSIFICATION:
Based on mechanism of release of
drug
Based on type of degradation
 Based on the source
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17. 1.Based on the mechanism of release:
Slow dissolution and erosion by hydrolysis Water
insoluble polymers degradation of pendent group
without backbone cleavage.
Water insoluble polymer degrades to water-soluble
products by backbone cleavage
H2O soluble Swelling Dimensional stability H2O
insoluble Chemical change No backbone cleavage H
2 O insoluble Chemical cleavage MW↓
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18. 2. Based on type of degradation :
which contains both physical (dissolution) and
chemical (backbone cleavage) process. Chemical
degradation
Mechanism Of Degradation
 Bioerosion
 Surface erosion
 Chemical Degradation
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19. Bioerosion:
Bulk erosion Surface erosion Bulk erosion:
Degradation takes place through out the whole of the
sample Ingress of water is faster than the rate of
degradation Eg : Polylactic acid (PLA) Polyglycolic
acid (PGA)
Surface erosion
Sample is eroded from the surface Mass loss is faster
than the ingress of water into the bulk Eg :
Polyanhydrides , polyorthoesters
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20. Chemical degradation
mediated by water , enzymes , microorganisms
Cleavage of cross-links transformation of side chains
cleavage of backbone
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21. 3. Based on Source:
 Synthetic biodegradable polymers
eg : Aliphatic poly(esters)
Polyanhydride
Polyphosphazene
Pseudo polyaminoacid
Poly( orthoesters ) etc.,
 Natural biodegradable polymers:
eg : Albumin
Collagen
Gelatin etc.,
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22. Example of Some (Natural) Biodegradable Polymers:
 Collagen:
collagen Prime function is to check tissue deformation and
avoid mechanical failure. Advantages: It is a major
structural protein in animals It is used as sutures
,Dressings, etc. Readily isolated & purified in large
quantities. Can be processed in variety of forms .
 Disadvantages
Poor dimensional stability. Variability in drug release
kinetics. Poor mechanical strength.
 Application:
Majorly used in ocular drug delivery system
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23. Example of Some (Natural) Biodegradable Polymers:
 Albumin:
It is a major plasma protein component. It accounts for
more than 55% of total protein in human plasma. It is used
to design particulate drug delivery systems.
 Application: :
Albumin micro-spheres are used to deliver drugs like
Insulin, Sulphadiazene , 5-fluorouracil, Prednisolone etc. It
is mainly used in chemotherapy , to achieve high local drug
concentration for relatively longer time.
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24. Example of Some (Natural) Biodegradable Polymers:
 Gelatin:
Heterogeneous products obtained by hydrolytic extraction
of treated animal collagen. Physicochemical properties
depends on the source of collagen, extraction method and
thermal degradation.
 Applications :
Employed as matrix and as coating material. Gelatin
micropellets are used for oral controlled delivery of drugs.
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25. Example of Some (Natural) Biodegradable Polymers:
 Dextran :
Dextran is a complex branched polysaccharide made of
many glucose molecules joined into chains of varying
lengths. It consists of α-D-1,6-glucose-linked glucan with
side-chains linked to the backbone of Polymer. Mol.wt
ranges from 1000 to 2,00,000 Daltons
 Applications :
Used for colonic delivery of drug in the form of gels
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26. Example of Some (Synthetic) Biodegradable Polymers:
 Lactide /glycolide polymers:
Most widely used biodegradable polymers Lactide /
glycolide are the simplest aliphatic polyester
Biodegradation : Undergo biodegradation by bulk erosion.
Cleaved by hydrolysis to monomeric acids and eliminated
through kreb’s cycle. Enzymatic degradation is also
reported.
 Applications :
Used to deliver drugs in the form of microspheres ,
implants etc., Examples of drugs delivered include steroid
hormones, antibiotics, anti cancer agents etc.,
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27. Example of Some (Synthetic) Biodegradable Polymers:
 Polycaprolactone:
semi-crystalline polymer slower degradation rate than PLA
remains active as long as a year for drug delivery
Biodegradation: Occurs in two phases: First phase:
hydrolytic chain scission of the ester linkage Second phase:
decrease in the rate of chain scission and onset of weight
loss due to: Diffusion of small mol wt polymer Breakup of
polymer mass to produce smaller particles
 Applications: :
Drug delivery applications of PCL includes: - Cyclosporin in
the form of nanoparticles - Ciprofloxacin in the form of
dental implants
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28. Example of Some (Synthetic) Biodegradable Polymers:
 Poly anhydrides:
Compression and injection moulding methods are
employed to formulate matrices bearing drug. B
iodegradation: Degrades by surface erosion Carboxylic
anhydride bond in the polymer chain is responsible for fast
erosion. Degradation is faster in basic than acidic media.
 Applications:
Suitable for short term drug delivery Used for vaccination
and localized tumor therapy.
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29.  Polyphosphazenes:
Hydrolytic stability/instability is determined by change in
side group attached to macromolecular backbone. Based on
side chain these are of 3 types: Hydrophobic phosphazenes
Hydrophilic phosphazenes Amphiphilic phosphazenes
 Applications: :
Used in the construction of soft tissue prosthesis, tissue like
coatings, as material for blood vessel prosthesis. Used for
immobilization of antigen or enzyme
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30. Example of Some (Synthetic) Biodegradable Polymers:
 Poly orthoesters:
Poly orthoesters These have acid- labile linkages in their
backbone. Acid excipents causes fast erosion whereas basic
excipients causes long term erosion.
 Application:
Used in contraceptive steroid bearing bioerodible polymer
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31. ADVANTAGES OF BIODEGRADABLE POLYMERS:
 Localized delivery of drug Sustained delivery of drug
 Stabilization of drug
 Decrease in dosing frequency
 Reduce side effects
 Improved patient compliance
 Controllable degradation rate
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32. BIODEGRADABLE POLYMERS IN ADVANCED
DRUG DELIVERY:
POLYMERIC MICELLES: used to deliver therapeutic
agents.
HYDRO GELS: these are currently studies as
controlled release carriers of proteins & peptides.
The polymer matrix can be formulated as either
micro/ nano -spheres, gel, film or an extruded shape.
The shape of polymer can be important in drug
release kinetics .
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33. Conclusion:
 Numerous synthetic biodegradable polymers are available and
still being developed for sustained and targeted drug delivery
applications. Biodegradable polymers have proven their
potential for the development of new, advanced and efficient
DDS and capable of delivering a wide range of bioactive
materials.
 However, only few have entered the market since many drugs
faces the problem of sensitivity to heat, shear forces and
interaction between polymers. These problems can be overcome
by fully understanding the degradation mechanism to adjust the
release profile.
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34. References:
 Controlled and Novel D rug D elivery by N. K. Jain; pg no:
27-51.
 Controlled Drug D elivery C oncepts and Advances by
S.P.Vyas Roop K.Khar ; pg no:97-155.
 Novel Drug Delivery Systems by Yie W Chien ; second
edition; pg no:32-34.
 Design of Controlled Release Drug Delivery System by
Xiaoling Li, Bhaskara R. Jasti ; pg no:271-303.
 International Journal of Pharma Research and
Development; volume 2
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