Biodegradable polymers

Applications of Biodegradable polymers

1. BIODEGRADABLE
POLYMERS
Presented by : Dr. Shrestha Sharma
M.Pharma, PhD(Pharmaceutics)

2. WHAT IS BIODEGRADABLE POLYMER?
Biodegradation:-means gradual breakdown of a
material mediated by a specific biological activity
“Biodegradable” polymers are materials with the
ability of functioning for a time periodand
subsequently degrade, under a controlled
mechanism into products easilyeliminatedin body
metabolic pathways
“Nature’s way: every resource made by nature
returns to nature. Nature has perfected the system
we just need to figure out how “

3. WHY WOULD A MEDICAL PRACTITIONER
LIKE A MATERIAL TO DEGRADE IN BODY?
Do not require a
second surgery for
removal
Offer tremendous
potential as the basis
for controlled drug
delivery
Do not evoke any
immunogenic response

4. IMPORTANT PROPERTIES OF
BIODEGRADABLE POLYMERS
Material should not evoke any sustained
inflammatory or toxic response upon implantation
in the body
Material should have acceptable shelf life
Degradation time should match healing or
regeneration process
Should be non toxic , able to get metabolisedand
clearedfrom body
Material should have appropriate permeability and
processibility for intended application

5. CLASSIFICATION BASED ON SOURCE OF
DERIVATION
Biodegradab
le polymers
Biomass
product
(agro-
resources)
polysaccharide
s
starch
wheat
Pectin
Chitin
Cellulose
products
Proteins and
lipids
Collagen
gelatin
Soya
Zein
gluten
From
microorganis
m(by
extraction)
Polyhydroxy
alkonaotes
Polyhydroxy
butyrate
From
biotechonolo
gy(bio-
derived
monomers)
polylactides
Polylactic
acid
From
petrochemic
al products
Polycaprolacto
e
Polyester
amide
Aliphatic
poly co ester

6. CLASSIFICATION ON THE BASIS OF MODE OF
DEGRADATION
Biodegradabl
e polymers
Hydrolyticall
y degradable
polyesters
Polyglycolide
Polylactide
Poly(lactide
coglycolide0
Polly
caprolactone
polyanhydride
s
Polysebacic
acid
Poly adipic
acid
polyacetals
polyketals
polyurethanes
Enzymaticall
ydegradable
Proteins and
amino acids
Collagin
gelatin
Polyglutamic
acid
polysaccharide
s
Non human
origin
Chitosin
Alginicacid
agarose
Human
origin
Hyaluronic
acid
Chondritin
sulphate

7. ADVANTAGES OF SYNTHETIC
BIODEGRADABLE MATERIALS
Tailor-able properties
Predictable lot-to-lot uniformity
Free from concerns of
immunogenicity
Reliable source of raw materials

8. FACTORS INFLUENCING THE
DEGRADATION BEHAVIOUR
Physicochemical factors
Morphology (crystallinity, presence of
microstructure, orientation)
Chemical structure and composition
Molecular weight
Solubility
Hydrophilicity, hydrophobicity
Water absorption
Site of implantation
Mechanism of hydrolysis (enzymes vswater)

9. STEPS OF DEGRADATION
Water sorption
Reduction of mechanical properties
(modulus and strength)
Reduction of molar mass
Weight loss

10. DEGRADATION SCHEMES
a) Bulk erosion(PLA,PGA,PLGA,
PCL)
Degradation takes place throughout
the whole of the sample
Ingress of water is faster than the
rate of degradation
b) 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

11. POLYMER DEGRADATION BY EROSION

12. MEDICAL APPLICATIONS OF
BIODEGRADABLE POLYMERS
Dental applications
Guided tissue
regeneration Membrane
Void filler following tooth
extraction
Bases , liners and
varnishes for cavities
Cardiovascular applications
Stents
Intestinal applications
Anastomosis rings
Tissue engineering

13. MEDICAL APPLICATIONS-BIODEGRADABLE POLYMERS
Wound management
Sutures
Staples
Clips
Adhesives
Surgical meshes
Orthopedic devices
Pins
Rods
Screws
Ligaments

14. Pharmaceutical applications of biodegradable
polymers
Drug delivery system:-
Nanoparticles
Microparticles
Transplants
Sustained release formulations
Controlled release delivery
Protein encapsulation and delivery
Brain targeting
Chemotherapy

15. POLY ESTERS
Most extensively studied class of polymers
They are thermoplastic polymers with
hydrolytically labile aliphatic ester linkages
Among polyesters –most investigated class
is poly hydroxyacid (poly glycolic acid and
poly lactic acid)
Developed from ring opening and
condensation polymerization

16. POLYGLYCOLIDE
Properties-highly
crystalline(45-55%) ,
Tg(35-40),excellent fibre
forming ability.
DEXON –first
BIODEGRADABLE
synthetic suture
Disadvantages–high
rate of degradation ,low
solubility , degradation by
products . So
copolymersused

17. POLY LACTIC ACID
Lactic acid:
is a chiralmolecule
 exist in L-, and racemicform
Only L –Lactideoccurs naturally
PLLA –(Poly L-lactic acid)
Crystalline form .Tg–60-65 ,, M.P, -175
Very slow degrading polymer
Good tensile strength
Low extension
More hydrophobic
More resistant to hydrolysis
Loses strength in around 6 months
PDLA-(Poly D-lactic acid )
Amorphous form .Tg–55 -60
Low tensile strength
Faster degradation time
Losses strength in 1 –2 months

18. APPLICATIONS OF POLY LACTIC ACID
 PLLA applications:-
1. Due to high tensile strength, used for load bearing applications as orthopaedic fixation
devices and a scoffolding material for ligament replacement
2. Also used in resorbable medical implants in shape of rod ,plate,screw,sponge,tissue
engineering
3. Due to slow degradation used as sustained release delivery
 PDLA applications :-
1. Due to faster degradation rate , preferred candidate for delivery vehicle in the form of
microspheres
2. Protein encapsulation and delivery
3. Also can be used for brain targeting in the form of nanoparticulates.
 Limitations of poly lactic acid :-
1. Difficulty in controlling hydrolysis
2. Poor hydrophilicity
3. Rigity and crystallinity
 To overcome limitations blended with starch ,chitosan , PCL, PEG etc
 starch reduces cost but decreases tensile strength
 Chitosan has good cell adhesion but low mechanical strength

19. POLY(LACTIDE-CO-GLYCOLIDE)
Most widely investigated
biodegradable polymer
It is a copolyester of lactic acid
and glycolic acid..combines
properties of both
Composition range 25 -75%
form amorphous polymer
On increasing the % of lactic
acid , stability towards
hydrolysis increases ..but
50:50 ratio of LA to GA is
highly unstable
50:50 ratio of LA:GA degrades
in 1-2 months
75:25 ratio LA:GA degrades in
4-5 months
85:15 ratio LA:GA degrades in
5-6 months

20. APPLICATIONS OF POLY (LACTIDE-CO-GLYCOLIDE)
1 PURA SORB : semicrystallinebioresorbablecopolymer. 80L:20G
2 VICYL : multifilament suture 90%GA:10%LA
3 PANACRYL :modified versionof vicryl, higher LA/GA ratio leading
to decrease in rate of degradation
4 LUPRON DEPOT : drug delivery vehicle composed of PLGA used
for release of gonadotrophinreleasing hormone analog for prostate
cancer and endometrosis
OTHER APPLICATIONS :
 Also used in making meshes , suture reinforcement , skin
replacement material
Tissue engg, skin graft
Also used for controlled release of drug in the form of microspheres,
microcapsules , nanospheres,nanofibres
Used in the form of nanoparticlesfor brain targeting
Novel chitin/ PLGA microspheres developed for delivery of protein

21. POLYKETALS
Hydrophobic polymers with biodegradable
ketal linkage
Advantages over conventional polymers :-
1.Like polyesters do not release acid on
degradation
2.Do not cause any inflammation at targeted
site..
3.Stablein both acids and bases (can be used
oral drug delivery)
4.Degrades only in presence of reactive
oxygenspecies, which is present around
inflamed tissues

22. APPLICATIONS OF POLYKETALS
Used in form of microparticles
and nanoparticles for treatment
of inflammatory diseases
(lung injury , acute liver failure
and inflammatory bowel
disease)
For the treatment of liver failure
,enzymesuperoxide
dismutaseincorporated inside
polyketals for delivery of enzyme
at targeted site
Another application is incase of
protein deliverywhere proteins
are immobilised on the surface
of microparticles
Also researches on insulin
delivery for type 1 diabetes

23. CHITOSANAND ITS PROPERTIES
Most promising biodegradable polymer
,produced commercially by deacetylation of
chitin which is structural element in
eoskelton of crustaceans
Unique properties :-
Bioahesiveness,binds to –vely charged
surfaces as mucosal memb. (enhances
transport of polar drugs across epithelial
surfaces)
Formation of gels with controlled
degradability in physiological conditions
Specific cellular interaction that can be used
target drug to specific cell types
Biocompatible, anti bacterial.
Do not cause inflammation to human
tissues,
Do not induce antibody formation
Low mechanical strength

24. APPLICATIONS OF CHITOSAN
Helps in rapid clotting of blood, used in bandages and other
haemostatic agents.
CELOX :marketed prepn. Quickly stops bleeding
Fat attractor, helps in reducing fat, hypolipemic formulations include
particles, powders, soln , injection prepn
Mucoadhesive chitosan microspheres for non-invasive and improved
nasal delivery of insulin(able to open tight junctions in nasal epithelia ,
permitting drugs to diffuse through this barrier)
Chitosan and its derivative trimethyl chitosanused in non viral gene
delivery
Used as brain targeting of drugs in form of NPs as used in delivery of
cholinesterase inhibitor (chitosan NPs increase circulation time time in
blood and decreased uptake by RES)
Also used for delivery of anti cancer drugs , selectively aggregate
leukemia tumour cells
Trimethyl chitosan , shown to transfect breast cancer cells with
increased degree of trimethylation , increasing cytotoxicity
Combined with PCL used as local oral mucoadhesive controlled release
delivery of drugs to buccal mucosa

25. ALGINIC ACID AND ITS APPLICATIONS
present in cell walls and intercellular
spaces of brown algae
Non branched binary copolymer of
mannuronicacid andglucuronicacid
Due to high acidcontent –undergo
spontaneous and mild gellingin p/o
cations as Ca (allows encapsulation
of no. of drugs)
Improves efficiency of delievery of
drugs and targeting
Disadvantages:-
Poor adhesion
Inability to undergo enzymatic
degradation

26. POLYANHYRIDES AND ITS APPLICATIONS
Extensively investigated
surface eroding
biodegradable polymer
Most hydrolytically labile
polymer
Used for short term release
of drugs
Rapid degradation and
limited mechanical
properties render them
ideal for controlled drug
delivery
Treatment of brain cancer

27. HYALURONIC ACID AND ITS APPLICATIONS
Member of glycosaminoglycanfamily
Water soluble
Forms highly viscuos solutions
Unique viscoelasticproperties
Found in high concn. In synovial fluidand vitreous humour
Applications :-
Approved for use in eye surgery(corneal transplantation , cataract ,
glaucoma )
Used to treat osteoarthritis of knee
Due to biocompatibility , used as scaffolds in tissue engg.
Used as tumour markerfor prostate and breast cancer
Tissue healing
Wound dressing applications

28. References
www.sciencedirect.com
www.cpia.ca/anti-litter
www.biodeg.net
en.wikipedia.org/wiki
www.clemson.edu
www.gatech.edu
www.amazon.com
www.mdpi.com
www.ebookee.com
www.nims.go.jp
www.biomed.metu.edu
www.nims.go.jp

29. Thank you