the presentation is about the natural polymers i.e. classification, applications, properties and examples. it is in 25 pages in shortcuted manner and simple method.
2. CONTENTS:
Introduction
Definition
Classification of natural polymers
Properties and disadvantages
Biodegradation mechanisms
Factors affecting on biodegradation of natural
polymers
Uses and applications
Examples
3. INTRODUCTION
A polymer is a large molecule (macromolecules) composed
of many repeated subunits, known as monomers.
Natural polymers and their derivatives are commonly used
in medicine and pharmacy.
Particular attention has recently been paid to natural
polymers, because they are biocompatiable and
biodegradable, so they can be hydrolyzed into removable
and non-toxic products.
monomer monomer Dimer polymer
Repeat
attachment of
monomers
4. DEFINITION
The natural polymer is produced by living
organisms and result from only raw materials
that are found in nature.
5. CLASSIFICATION
Classification of Natural polymers
Based on source
Plant Animal Microbes
Polysaccharides
e.g. Cellulose, Starch,
Alginate.
Proteins
e.g. Gluten
(Gelatin),
Albumin.
Polysaccharides
e.g. Chitin
(Chitosan),
Hyaluronate.
Polyesters
e.g. Poly(3-
hydroxylalkona
te) dervitives.
Polysaccharides
e.g. Hyaluronate.
The natural polymers are classified based on source or
structure.
7. NATURAL RUBBER
Natural rubber is another example of a
natural polymer.
It is made from only Carbon and
Hydrogen.
It is a product of Isoprene polymerization.
Isoprene
Polymer
n
prene:
rubber
Natural rubber
8. PROPERTIES & ADVANTAGES
Most of natural polymers are naturally built by condensation polymerization
Natural polymers tend to be readily biodegradable - they show no adverse
effects on the environment or human beings.
Non-toxic/ non-inflammatory - all of these materials are carbohydrates or
proteins in nature and composed of repeating monosaccharide or amino acid
units respectively. Hence they are non-toxic.
Biocompatible - their rate of degradation is generally inversely proportional to the
extent of chemical modification
Highly porous
For molecular weight the average molecular weight that can be only defined
Easy and cheap to preparation and production in comparison with synthetic
polymers
Capable of attachment with other molecules – most of these materials have
variety of functional groups leading to readily modify
Easy availability and renewable resources
9. DISADVANTAGES
Microbial contamination during production due to their
natural sources.
Batch to batch variation – as result to difference of
resources and resource regions.
Slow Process – as the production rate is depends
upon the environment and many other factors, it
can’t be changed. So natural polymers have a slow
rate of production.
potential impurities – may also result in unwanted
immune reactions.
Heavy metal contamination – that often associated
with herbal polymeric excipeints.
10. BIODEGRADATION MECHANISMS
The term 'biodegradation' is limited to the chemical processes that
alter either the molecular weight or solubility of the polymer
Natural polymers are biodegradable since they have unstable links
in their backbone and structure
They are broken down into biologically acceptable molecules that
are metabolized and removed from the body via normal metabolic
pathways
BIODEGRADATION
ENZYMATIC
DEGRADATION COMBINATIONHYDROLYSIS
BULK EROSION SURFACE EROSION
11. FACTORS AFFECTING BIODEGRADATION OF POLYMERS
Morphological factors
Shape & size
Chemical factors
Chemical structure & composition
Presence of ionic group and configuration
structure
Molecular weight
Physical factors
Variation of diffusion coefficient
12. USES & APPLICATIONS IN PHARMACY
The wide range of properties and applications
vary depending on studied natural polymer
They are either additives or active materials.
Gene and drug delivery systems.
Release-controlled drug delivery systems.
Protecting of susceptible drugs or plasmids from
degradation.
Offer different and more easily routes for drug
administration
13. CHITOSAN:
Introduction:
Chitin is a macromolecule found in the shells of crabs,
lobsters, shrimps and insects
Chitosan is obtained by partial deacetylation of chitin.
Chitin is insoluble in its native form but chitosan, the
partly deacetylated form, is water soluble.
Chemistry:
linear co-polymer of β(1-4) linked glucosamine and N-
acetyl-D-glucosamine.
14. PHYSIOCHEMICAL PROPERTIES
Odorless, white or creamy-white powder
Chelates many transitional metal ions
Highly basic polysacharides
in acidic pH, it gets solubilized due to protonation of
free amino groups and the resultant soluble
polysaccharide is positively charged.
hydrophilic in nature thereby it has the ability to form
gels at acidic pH.
Degraded by lysozyme to it’s by products
glucosamine and n-acetyl glucosamine
15. APPLICATION
Ocular delivery:
making contact lens- optical clarity, sufficient optical
correction, gas permeability, particularly towards oxygen,
wettability and immunological compatibility.
antimicrobial and wound healing properties of chitosan
along with an excellent film capability make chitosan
suitable for development of ocular bandage lenses.
Colon drug delivery:
Degraded by microflora present in human colon which
supports colon drug delivery
Coating material:
Good film forming property and mucoadhesive property
16. Mucosal delivery:
Chitosan gets protonated in acidic solution, so it binds
strongly to negatively charged cell surface making it
useful to formulate bioadhesive dosage forms.
Transdermal drug delivery:
Studies on propranolol hydrochloride (prop-HCl)
delivery systems using various chitosan membranes
with different crosslink densities as drug release
controlling membranes and chitosan gel as the drug
reservoir have been performed.
Gene Delivery:
Chitosan, typically isolated from the shell of shrimp,
has the ability to react with DNA and compact it to
produce a nanoparticle. Such nanoparticles are more
readily taken up by cells.
17. HYALURONIC ACID:
Introduction
Carbohydrate polyanionic mucopolysacharide, occurring naturally in
all living organisms.
Can be several thousands of sugar long
One of most hydrophilic molecules, also known as natural
moisturizer
Generally found in sodium salt form i.e. as sodium hyaluronate
Chemistry
The alternating disaccharide units are linked by (1→4) inter
glycosidic linkage.
Chains consist upto 30,000 repeating units so it has high molecular
weight range (1000 to 10,000,000 Da).
18. PROPERTIES
Biodegradable, biocompatible, non-toxic, non-
immunogenic, non-inflammatory, linear chain
polysaccharide
very hydrophilic; it adsorbs water making it hygroscopic
readily soluble in water, and produces a gel
Its viscous solutions have unusual rheological properties
(pseudoplasticity) and are exceedingly lubricious
To improve the mechanical properties and control the
degradation rate, HA can be chemically modified or
crosslinked to form a hydrogel
The gel is dependent upon a number of factors including
the length of the chain, cross-linking, pH
19. APPLICATION
They are used in the preparation of gels for delivery
of drugs to eye and installation into other cavities.
Microparticulate HA carrier:
Sustained-release formulations (e.g. protein drugs) have
been developed using spray-dried HA microparticles
which act as a protein reservoir
Also protects the drugs from denaturation and increases
their bioactivity
Ocular drug delivery:
Its viscosity and pseudoplastic behavior which provide
mucoadhesive property can increase the ocular
residence time
20. Cell targetting:
The expression of CD-44 (cluster determinant 44) and
RHAMM (receptor for hyaluronate-mediated motility)
receptors by various tumour cells, which are endogenous
ligands for HA, makes this a good candidate for drug
targeting to cancer cells
Nasal delivery:
A nanocarrier composed of hyaluronic acid(HA) and
chitosan(CH) was reported to encapsulate bovine serum
albumin (BSA) and cyclosporine A for the nasal delivery of
macromolecules
Topical drug delivery:
Surface hydration and film formation enhance the
permeability of the skin to topical drugs also promotes
drug retention and localization in the epidermis
HA has been used in tissue engineering for the cartilage
replacement in the joints
Used in cosmetics, skin care system, as anti ageing
therapy (antioxidant nature)
21. GELATIN:
INTRODUCTION
Gelatin is a natural water soluble functional polymer (protein)
that is derived by partial hydrolysis of collagen (chief protein
component in skin, bones and white connective tissues of the
animal body).
It is commonly used for pharmaceutical and medical
applications because of its biodegradability and
biocompatibility in physiological environments.
GELATIN TYPES
Gelatin derived from an acid-treated precursor is known as
Type-A and gelatin derived from an alkali-treated process is
known as Type-B.
Results in a difference in isoelectric points (IP), being 7 – 9 for
gelatin type A and 4 – 5 for gelatin type B.
23. PHYSICOCHEMICAL PROPERTIES
Formation of thermo-reversible gels in water: When gelatin granules are
soaked in cold water they hydrate into discrete, swollen particles. On
being warmed, these swollen particles dissolve to form a solution.
Soluble in aqueous solutions of polyhydric alcohols such as glycerol and
propylene glycol.
Insoluble in less polar organic solvents such as benzene, acetone,
primary alcohols and dimethylformamide.
Gelatin stored in air-tight containers at room temperature remains
unchanged for long periods of time. When dry gelatin is heated above
45° C in air at relatively high humidity (above 60% RH) it gradually loses
its ability to swell and dissolve.
Sterile solutions of gelatin when stored cold are stable indefinitely; but at
elevated temperatures the solutions are susceptible to hydrolysis.
Gelatin is composed of 50.5% carbon, 6.8% hydrogen, 17% nitrogen
and 25.2% oxygen. It gives typical protein reactions and is hydrolyzed
by most proteolytic enzymes to yield its peptide or amino acid
components.
24. APPLICATION
Two-Piece Hard Capsules
Soft Elastic Gelatin Capsules
As a binder in Tablet
Tablet Coating
Suppositories
Gelatin Emulsions
Microencapsulation
Source of essential amino acids
Absorbable Gelatin Sponge
Gelatin as Nanoparticle and microparticles.
25. ALBUMIN
Introduction:
It is a major plasma protein component.
It accounts for more than 55% of total protein in human
plasma.
There are two specific types includes:
human serum albumin
bovine serum albumin (BSA): often used in medical and
molecular biology labs.
Applications:
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.
