Pharmaceutical sciences

1. POLYMERS
Presented BY
Miss Pallavi Jadhav

2. INTRODUCTION
 Drug delivery system often requires synthetic components or biomaterials.
Frequently these materials are Polymers.
 In pharmaceutical preparations they have several applications such as in mfg of
bottles, vials, catheters & many of the drug formulations.
 “Polymer” word is derived from Greek roots “Poly” meaning many & “Meros”
meaning parts.
 Definition :
Polymers are long chain of organic molecules made by bonding of
repeating subunits called as monomers.

3. CLASSIFICATION
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, Polyamides, Polyanhydrides.
c) Semi-synthetic polymers :
e.g. Cellulose nitrate, Cellulose acetate, Vulcanized rubber etc.

4. B) Based on Bio-stability :
a) Bio-degradable polymers :
e.g. Proteins, Carbohydrates, Polylactic acid, Polyglycolic acid.
b) Non Bio-degradable polymers :
e.g. Ethyl cellulose, HPMC, Acrylic Polymers, Silicones.
C) Based on reaction mode of polymerization :
a) Addition polymers :
Monomer molecules bond to one another without the loss of any molecule.
e.g. Alkenes( polythenes )
b) Condensation polymers :
Two similar or different molecules combine with the loss of one water
molecule.
e.g. Polyamides, Polyesters, Polystyrene.

5. D) Based on interaction with water :
a) Non Bio-degradable hydrophobic polymers :
Inert compounds, eliminated intact from the site of application.
e.g. Polyethylene, PVC, Vinyl acetate.
b) Hydrogels :
Swell but do not dissolve when in contact with water.
e.g. Polyvinylpyrrolidone(Povidone).
c) Soluble polymers :
Moderate mol. Wt. cross-linked polymers that dissolve in water.
e.g. PEG, HPMC.

6. E) Based on thermal properties :
a) Thermoplastics polymers :
Polymers which soften on heating become firm again on cooling
e.g. Polyester, Teflon, Polystyrene.
b) Thermosetting polymers :
Polymers that soften on heating & can be molded but harden permanently
e.g. Bakelite.
F) Based on structure :
a) Linear polymers : Polyamides, Polyethylene, PVC, Polystyrene etc.
b) Branched chain polymers: Starch, Glycogen etc.
c) cross-linked polymers: Bakelite, Polyurethanes etc.

7. Polymers display different properties such as physical, thermal, mechanical properties depending
on multiple factors.
1) Physical Properties :
A) Crystalline & amorphous properties :
If polymers chains are arranged in a regular array which forms a regular geometric matrix
then it is said to be in crystalline state.
In many cases polymers chains are arranged irregularly that crystal formation is
thermodynamically impossible, such polymers are in amorphous state.
B)Optical properties :
Optical properties of polymers are drawn based on their crystallinity. R.I. are different for
crystalline & amorphous polymers.
C) Degree of polymerization : No. of repeating subunits in a polymer chain. [-CH2 - CH2-]n
PROPERTIES

8. 2) Thermal Properties :
Glass Transition Temperature(Tg) : It is the temperature at which glassy polymer
changes to a rubbery state. Tg plays imp role in determination of hardness & elasticity.
3) Mechanical Properties :
a) Tensile strength : Ability of polymer to resist against stretching.
b) Compressional strength : Ability of polymer to withstand load.
c) Flexural strength : Also known as bend strength.
d) Impact strength : Ability of polymer to withstand against sudden impact or shock.

9. Criteria For Polymer Selection
 Solubility in the given solvent
 Inertness
 Easy to obtain/synthesize
 Finite mol. Wt.
 Compatibility with biological environment i.e. should be non toxic & non
antigenic
 Should be biodegradable or easily eliminated from the body after its function is
over.

10. Applications
• In Dosage forms :
A) Tablets :
Binders : MC, EC, HPEC, HPC, SCMC etc.
Diluents : Starch, Cellulose, Lactose etc.
Antiadherents, Glidants : Corn starch etc.
Coating material : CAP, Acrylate polymers, HPMC phthalate, HPMC, EC etc.
B) Liquids :
Suspending agents : Acacia, Tragacanth, Cellulose derivatives etc.
Viscosity enhancers : Polyacrylic acids, CMC, gelatin etc.
Emulsifiers : Spans( Sorbitan Fatty acids, 1<HLB<8 ) – span 20, span 60
Tweens( Polyoxyethylene adducts, 9<HLB<16) – tween 20, tween 80

11. C) Semisolids :
Gel preparation/Hydrogels : Polydivinyl benzene, Polydimethyl siloxane.
Ointments : MC, HEC, Carbopols etc.
D) Transdermal patches :
Gelating agents : Pectin, gelatin, Sodium alginates, Polivinyl alcohol clays etc.
Penetration enhancers : Pyrrolidones etc.
E) Reservoir systems : (Most commonly used)

12. F) Matrix systems :
Hydrophilic matrix : high mol. wt., HPMC, HPC, HEC, PEO & cross linked acrylic acid
Hydrophobic matrix : Insoluble or non digestible, EC or polymethacrylates.
G) Swelling controlled release system( Gastro retentive) :
Hydrogels – Poly Etheylene Oxide, Poly Vinyl Alcohol, Polypropylene fumarate
H) Osmotically controlled drug delivery :
Semipermeable membranes : Cellulose acetate.
I) Ocular DDS :

13. J) Mucoadhesive systems :
• Biomedical applications :
Tissue Engineering Bone fixation devices
Vascular grafts Surgical adhesives
Biosensors Fixators
Implants mfd Dental materials

14. Thank You