3. Introduction
Polymer is a combination of two greek words.
i.e poly means “many” & meros means “parts of units”.
Definition :
Polymers is a long chain organic molecules in which, it is
linking from small molecules, this known as called as
monomers.
More monomers molecules are joined a large units of long
polymers.
4. On the basis of Monomer Arrengements:-
Co-polymer :-
Polymers formed from two or more different
monomers are called as Copolymers.
- [A – B – A – B – A – B] –
Homo-polymer :-
Polymers formed from bonding of monomers are called as
Homopolymers.
- [A – A – A – A – A] -
5. Classification of Polymers -
1) Polymers based on Backbone.
2) Natural and Synthetic polymers.
1) Polymers based on Backbone.
1) Polymers with carbon chain.
Eg. polypropylene, polychloride.
2) Polymers with heterochain.
Eg. polyethylene oxide, polypropylene oxide, cellulose.
6. 2) Natural Polymers –
1) Protein based.
E g. Albumin, Gelatin.
2) Polysaccharide.
E g. Polysialic acid.
3) Synthetic Polymers.
1) Biodegradable.
2) Non biodegradable.
1) Biodegradable.
E g. polyesters, polyamides,
polyhydrides.
7. 2) Non biodegradable.
E g. Cellulose derivatives, silicones,
Acrylic polymers, etc.
Biodegradable polymers -
Biodegradable polymers are made by chemical
linkage such as ester and amino chain.
The degradable mechanisms is done by hydrolysis
or enzymatic cleavages.
8. Properties
1) Molecular weight and Molecular weight distribution.
2) Polymer Hydrophobicity.
1) Hydrophobic polymers.
2) Hydrophilic polymers.
3) water soluble polymers.
4) Hydrogels.
1) Molecular weight and Molecular weight distribution.
It is random process & molecules within given polymer
mass will have different mol. Wt, and for this reason mol. wt.
of polymers are described in terms of average mol. wt.
9. 2) Polymer Hydrophobicity
when a polymer is placed in an aq. Environment, then it
will absorb water and the absorbed water is determined by
polymer structure. because polymeric controlled release expose
to the polymer.
i) Hydrophobic polymers
polymers are essentially water impermeable and when
placed an aq. Environment will absorb very Little water and there
is no fixed the amount of absorbed water below which is polymer
is hydrophobic.
ii) Hydrophilic polymers
There are polymers that absorb more 5 wt % water.
10. 3) Water soluble polymers -
some polymers are freely soluble in water and even
they are very high mole.weight.
for E g. - polyvinyl alcohol, polyethylene oxide.
4) Hydrogels -
These are highly hydrophilic or water soluble polymers
that have cross linked by covalent bond because the polymer
cannot dissolved due to covalent bond.
12. • Polymeric materials are used with soil to improve plant
growth.
• Pharmaceutical industry.
• Other industry.
Transdermal Patches :
- Drug is sandwiched between drug impermeable backing and
drug permeable rate controlling polymer.
E g. Ethylene-vinyl acetate copolymer
- In the reservoir, drug is dispersed in solid polymer matrix.
E g. Polyisobutylene
- On the external surface, there should be adhesive polymer.
E g. Silicone Polymer, Polyacrylates.
13.
14. Applications In Controlled Drug Delivery -
Matrix Systems
Drug particles are enclosed in a matrix environment formed by
cross-linking of polymer chains.
For the drug to get released, it has to be first dissolved in
surrounding polymer and then diffuse through the polymer
structure.
Example- Nitroglycerine releasing system for treatment of
angina pectoris.
15. Swelling Controlled Release Systems
Drug is enclosed in a collapsible drug compartment inside a
rigid, shape-retaining housing.
The shape between external housing and drug compartment
contains laminate of swellable, hydrophillic cross-linked
polymer.
e.g. polyhydroxyalkyl methacrylate.
This polymer absorbs GI fluid through annular openings in the
bottom of housing.
16. Drug delivery orifice
Shape retaining housing
Collapsible drug container
Swellable polymer
Liquid drug formulation
Annular openings
17. REFERENCE -
Text book of Introduction to novel drug delivary system, N.
K. Jain CBS Publisher, New Delhi, page no. 300-331.
Controlled Drug Delivery By- Robinson 2nd edition
page no.140 -169
