2. 22
WWhhaatt iiss PPoollyymmeerr??
• “Polymer” word is derived from Greek roots
“Poly” meaning many and “Meros”
meaning parts.
• Definition :
Polymers are long chain organic
molecules assembled from many smaller
molecules called as monomers.

3. 33
• Copolymer :
Polymers formed from two or
more different monomers are called as
copolymers.
- [A – B – A – B – A – B] –
• Homopolymer :
Polymers formed from bonding of
identical monomers are called as
homopolymers.
- [A – A – A – A – A] -

4. 44
CCLLAASSSSIIFFIICCAATTIIOONN
A. Based on origin :
a) Natural Polymers :
e.g. Proteins – Collagen, Keratin, Albumin
Carbohydrates – starch, cellulose,
glycogen.
DNA, RNA
b) Synthetic Polymers :
e.g. polyesters, polyanhydrides, polyamides.
B. Based on Bio-stability :
a) Bio-degradable Polymers :
e.g. polyesters, proteins, carbohydrates, etc
b) Non – biodegradable Polymers :
e.g. ethyl cellulose, HPMC, acrylic polymers, silicones.

5. 55
C. Based on Reaction mode of Polymerization :
a) Addition Polymers :
Here, the monomer molecules bond to
each other without the loss of any other
atoms.
e.g. Alkene monomers
b) Condensation Polymers :
Usually two different monomers combine
with the loss of small molecule, usually water.
e.g. polyesters, polyamides.

6. 66
D. Based on Interaction with Water :
a) Non – biodegradable Hydrophobic Polymers :
These are inert compounds and are eliminated
intact from the site of application.
e.g. polyethylene – vinyl acetate, polyvinyl chloride.
b) Hydrogels :
They swell but do not dissolve when brought in
contact with water.
e.g. polyvinyl pyrrolidone
c) Soluble Polymers :
These are moderate mol. wt uncross-linked
polymers that dissolve in water.
e.g. HPMC, PEG
d) Biodegradable Polymers :
These slowly disappear from the site of
administration in response to a chemical reaction such as
hydrolysis.
e.g. Polyacrylic acid. Polyglycolic acid.

7. 77
AApppplliiccaattiioonnss iinn CCoonnvveennttiioonnaall
DDoossaaggee FFoorrmmss
• Tablets :
- As binders
- To mask unpleasant taste
- For enteric coated tablets
• Liquids :
- Viscosity enhancers
- For controlling the flow
• Semisolids :
- In the gel preparation
- In ointments
• In transdermal Patches

8. 88
AApppplliiccaattiioonnss IInn CCoonnttrroolllleedd
DDrruugg DDeelliivveerryy
• Reservoir Systems
- Ocusert System
- Progestasert System
- Reservoir Designed Transdermal Patches
• Matrix Systems
• Swelling Controlled Release Systems
• Biodegradable Systems
• Osmotically controlled Drug Delivery

9. 99
A. Reservoir System :
 Ocusert System :
- Novel means of controlled ocular drug delivery
- Used for max 7 days treatment of Glaucoma
- Consists of core reservoir of pilocarpine &
alginic acid sandwiched between two sheets
of transparent, lipophillic, rate controlling
membrane of ethylene-vinyl acetate
copolymer.
- Inserted in cul-de-sac, lachrymal fluid enters the
system and the dissolved drug slowly gets
released through polymeric membrane.

10. 1100
 Progestasert system :
- Used for once-a-year contraception
- Consists of drug saturated liquid medium
encapsulated in a polymeric
membrane.
- Progesterone is released at a constant
rate of 65 μg/day.
- Polymers used are :
Silicone elastomers, polyethylene,
ethylene-vinyl acetate.

11. 1111

12. 1122
 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. 1133
TrTarnasndsedremrmaal lC Coonnttrroolllleedd DDrurug gD Deleivleivreyry

14. 1144
BB.. OOssmmoottiiccaallllyy CCoonnttrroolllleedd DDrruugg
DDeelliivveerryy SSyysstteemm
• Drug is coated with semi-permeable
polymer
e.g. Cellulose acetate.
• Water generates osmotic
pressure gradient by
permeating through semi-permeable
membrane.
• Due to that drug pumps
out of delivery orifice over
a prolonged time at a
defined rate.

15. 1155
CC.. BBiiooddeeggrraaddaabbllee SSyysstteemm
• Mainly used for parenteral controlled drug
delivery.
• Drug is encapsulated in biodegradable
microcapsules which are suspended in
aqueous / oleaginous medium and injected
subcutaneously or intra-muscularly.
• Polymers used for microcapsules are :
Gelatin, dextran, polylactate, lactide –
glycolide copolymer.
• The release of drug is controlled by the rate
of bio-degradation of polymer.

16. 1166
DD.. MMaattrriixx SSyysstteemmss
• 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.
• Polymers used are :
polyalkyls, polyvinyls, etc.
• Example – Nitroglycerine releasing system for
prophylaxis or treatment of angina pectoris.

17. 1177
EE.. SSwweelllliinngg CCoonnttrroolllleedd RReelleeaassee
SSyysstteemmss
• 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.

18. 1188
BBeeccaauussee ooff tthhiiss,, llaammiinnaattee sswweellllss aanndd ggeenneerraatteess
hhyyddrrooddyynnaammiicc pprreessssuurree aanndd iinndduucceess tthhee
ddeelliivveerryy ooff ddrruugg ffoorrmmuullaattiioonn tthhrroouugghh tthhee oorriiffiiccee..
Drug delivery orifice
Shape retaining housing
Collapsible drug container
Swellable polymer
Liquid drug formulation
Annular openings