This document discusses polymers and their applications in controlled drug delivery systems. It defines polymers as macromolecules formed by linking small molecule monomers through polymerization. Polymers are classified based on their structure (linear, branched, cross-linked), mechanism of formation (addition, condensation), origin (natural, synthetic), and degradability. Common polymers used in drug delivery include polyesters like PLA and PGA, polysaccharides like sodium alginate, and proteins like albumin and collagen. These polymers can be used to develop various drug delivery systems through diffusion, swelling, or erosion-based release.

1. By: Abdul Raheem
1st
Year Mpharm
Industrial Pharmacy
Bapuji Pharmacy college
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2. What is a Polymer?
Macromolecule.
It is defined as a large molecule consisting of many
repeatings which are formed by the process of
Polymerization.
Polymerization is the process of linking of small
molecules together.
These small molecules are called Monomers.
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3. Monomer:
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4. Types of Polymers:
These monomers are linked together in
different ways to form:
Linear Polymers
Branched Polymers
Cross linked Polymers
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5. Linear Polymers or Branched Polymers:
 Thermoplastic materials.
 They flow when heated.
 They can be fabricated by the application of heat
and pressure.
 They are soluble in certain solvents.
 Examples: Polyesters, Polyamides, Polyolefins,
LDPE, HDPE etc.
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6. Linear Polymers:
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7. Branched Polymers:
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8. Cross Linked Polymers:
 Thermosetting materials.
 They do not flow when heated.
 They cannot be fabricated by the application of heat and
pressure.
 Examples: Bakelite, Phenol-Formaldehyde polymers,
Urea-Formaldehyde polymers, Melamine-Formaldehyde
polymers, Glyptal Resins etc.
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9. Cross-Linked Polymers:
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10. Classification of polymers:
Polymers are classified based on:
 Method of polymerization
 Mechanism of polymerization
 Origin of polymers
 Degradability of polymers
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11. Method of polymerization:
Here the polymers are classified depending
upon the method of polymerization:
Addition polymers
Condensation polymers
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12. Addition polymers:
 In this the repeating units of the polymers have the
same molecular formula as the monomers.
 These are prepared by the polymerization of the
monomers bearing one or more double or triple bonds
or by the ring opening reactions of the cyclic structures.
 Examples: Low Density Poly Ethylene (LDPE), High
Density Poly Ethylene (HDPE), Poly Vinyl Chloride
(PVC), Poly Styrene (PS), Poly Tetra Fluoro Ethylene
(PTFE or TEFLON), Poly Vinyl Acetate (PVAc) etc.
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13. Addition polymers:
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14. Condensation polymers:
 These are formed by the successive reactions of the
functional groups.
 Since the by-product formed is a smaller molecule, the
repeating units of the polymers have fewer atoms than
the monomers.
 Examples: Polyesters like Dacron, Mylar etc. Polyamides
like Nylon 6, Nylon 66, Perlon, Kevlar, Nomex etc.
Polyurethanes like Spandex etc.
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15. Polyamide: Nylon
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16. Mechanism of polymerization:
Here the polymers are classified depending
upon the mechanism by which they are formed:
Chain (Addition) polymerization
Step growth (Condensation) polymerization
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17. Chain (Addition) polymerization:
 In this the polymerization reaction proceeds via discrete
initiation, propagation and termination steps.
 Once the polymerization starts, each polymer chain
undergoes rapid preferential growth in terms of
molecular weight with a steady decrease in monomer
concentration.
 Examples: Vinyl polymers were probably the first to be
synthesized in this manner.
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18. Chain Polymer: Teflon
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19. Step growth (Condensation) polymerization:
 In this there are no discrete initiation, propagation and
termination steps.
 Here the reaction proceeds via specific reactions
between the functional groups and thus any two
molecular species with appropriate groups react.
 The molecular weight of the polymer increases steadily
throughout the reaction and monomer disappears early
in the reaction.
 Examples: Polyesters like Dacron, Mylar etc. Polyamides
like Nylon 6, Nylon 66, Perlon, Kevlar, Nomex etc.
Polyurethanes like Spandex etc.
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20. Kevlar:
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21. Nomex:
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22. Spandex:
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23. Origin of polymers:
Here the polymers are classified depending
upon their origin.
Natural polymers: Example: Gelatin, Collagen etc.
Semi synthetic polymers: Example: EC, HEC, HPMC,
HPC etc.
Synthetic polymers: Example: PGA, PLA etc.
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24. Degradability of polymers:
Here the polymers are classified depending
upon their ability to degrade.
Biodegradable polymers: Example: Natural polymers
like gelatin, collagen etc and Synthetic polymers like PGA,
PLA etc.
Non-biodegradable polymers: Example: Semi synthetic
polymers like EC, HEC, HPMC, HPC etc.
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25. Ideal characteristics of a polymer:
 Should be inexpensive.
 Should be readily available.
 Should be easily processed on large scale.
 Should be biocompatible.
 Should be non-toxic.
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26. Importance:
 Polymers are used as carrier materials in the
formulation of controlled drug delivery systems.
 The selection of the polymer depends upon the
intended use and the desired release profile.
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27. Biodegradable Polymers:
 These are polymers consisting of monomers linked to
one-another through functional groups and have
unstable linkages in their back bone.
 These polymers are biologically degraded or eroded into
oligomers or monomers that can be metabolized and
excreted by the enzymes introduced in-vitro (or) by the
enzymes generated by surrounding living cells (or) by
the enzymatic processes.
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28. Ideal Characteristics of Biodegradable Polymers:
 They should be biocompatible – (shape, surface and
leachables).
 They should be bioabsorbable – (degradability profile,
reabsorption of degradation products).
 They should be bifunctional – (physical, mechanical and
biological).
 They should be stable – (processing, sterilization and
storage).
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29. Mechanism of Release through biodegradable
polymers:
 Diffusion
 Swelling
 Erosion
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30. Classification of Biodegradable Polymers:
 Natural Polymers:
 Proteins: Example: Albumin, Collagen, Gelatin etc.
 Polysaccharides: Example: Sodium alginate Chitin,
Chitosan, Cellulose, Dextran, Inulin, Hyaluronic acid,
Starch etc.
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31. Classification of Biodegradable Polymers:
 Synthetic Polymers:
 Aliphatic Polyesters: Example: Poly-Glycolic Acid (PGA),
Poly-Lactic Acid (PLA), Poly-Hydroxy Butyrate (PHB), Poly-
β-Malic Acid (PMA) etc.
 Poly Phospho Esters
 Poly Anhydrides
 Poly Phosphazenes
 Pseudo Amino Acids
 Poly Ortho Esters
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32. Natural Polymers:
 They are an attractive class of biodegradable polymers.
 They are derived from natural sources.
 They are easily available.
 They are relatively cheap.
 They qualify for a number of chemical modifications.
 They can be a protein or a polysaccharide in chemical origin.
 Modified natural polymers are natural polymers altered to improve
their biodegradation profile that can be achieved by chemical
modification or enzymatic alteration.
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33. Proteins:
Albumin:
 It is a major plasma protein component.
 It accounts for more than 55% of total protein in
human plasma.
 It is used to design particulate drug delivery
systems.
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34. Serum Albumin and Albumin:
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35. Advantages:
 It is easily available.
 It is biodegradable into natural products.
 Non-toxic and non-antigenic.
 The release pattern of drugs from albumin micro-
spheres is biphasic – initial burst release is followed
by a comparatively slower first order release.
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36. Factors affecting drug release from albumin
micro-spheres:
 Physicochemical properties and the concentration
of the drug.
 Interaction between the drug and the albumin
matrix.
 Size and density of microspheres.
 Nature and degree of cross-linking.
 Presence of the enzymes and pH of the
environment.
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37. Uses:
 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.
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38. Collagen:
 It is the primary structural protein.
 It occurs in the animal tissue as aligned fibres in
skin, connective tissue and the organic substance of
the bone.
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39. Collagen:
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40. Advantages:
 It is easy to isolate and purify in large quantities.
 It is biocompatible and non-toxic.
 It has well established physicochemical, structural
and immunological properties.
 It is easy to process collagen in various forms.
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41. Disadvantages:
 Poor stability.
 Variation in drug release kinetics.
 Low mechanical strength and elasticity.
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42. Uses:
Collagen shields are used in the ocular drug delivery
systems of drugs like Pilocarpine, Gentamycin etc.
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43. Polysaccharides:
Sodium alginate:
 Alginates are hydrophilic carbohydrates obtained
from various species of brown sea weeds, by the use
of dilute alkalies.
 They can be easily fabricated into particulate
systems.
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44. Sodium Alginate:
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45. Advantages:
 It protects the antigens and the vaccines against
degradation in GIT.
 It acts as an adjuvant.
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46. Uses:
 Alginates are particularly used as carriers of
peptides and other sensitive drug molecules since
particulate carriers can be easily prepared in
aqueous solution at room temperature.
 Alginate micro-spheres are efficiently used for oral
delivery of vaccines.
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47. Dextran:
 It is a polymer of glucose.
 It is prepared by subjecting the sucrose to the action of
the bacterium Leuconostoc mesenteroides.
 The crude high molecular weight dextran which is
formed is hydrolyzed and fractionated to yield dextran
of desired molecular weight.
 It is used in the form of a gel for colonic delivery of
drugs.
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48. SEM of Dextran:
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49. 49
Partially deacetylated chitin a cellulose – like
biopolymer consisting predominantly of N-acetyl-D-
glucosamine chains.
Chitosan and hydroxy propyl chitosan degrade
enzymatically, so used for implantable controlled
release dosage forms
Chitosan can be cross-linked with citric acid, EDTA,
or glutaraldehyde, and the cross-linked have been
applied to drug delivery systems

50. Synthetic Polymers:
 Most attractive class of polymers.
 Biocompatible and versatile in terms of physical,
chemical and biological properties.
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51. PGA and PLA:
 They are also known as poly-glycolic acid and poly-
lactic acid respectively.
 They are the simplest linear aliphatic polyesters.
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52. SEM of PGA and PLA:
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53. Biodegradation:
 PGA/PLA chains are cleaved by hydrolysis to form
monomeric acid units.
 They are eliminated in-vivo through Krebs’s cycle as
CO2 and in urine.
 PGA/PLA on hydrolysis Glycolic acid/Lactic→ →
acid Krebs’s cycle CO→ → ↑ 2 + Excreted in urine.
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54. Drug release from the polymer:
 Leaching of the contents from the polymer.
 Bio-erosion of the matrix.
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55. Poly-phospho esters:
 These are referred to as polyphosphates,
polyphosphonates or polyphosphites depending upon
the nature of side chain attached to phosphorus.
 These polymers are:
 Versatile
 Have good physicochemical profile
 Biocompatible
 These polymers are used to deliver paclitaxel and
cisplatin in the form of micro-spheres.
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56. APPLICATIONS IN CDDS
In Reservoir System
• Drug core is separated from biological fluids by a
water insoluble polymeric membrane
• Example of polymers used in reservoir systems are
Ethyl cellulose, Poly ethylene vinyl acetate, Silicone
etc.
Example for Reservoir systems are
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57. 1. Reservoir designed Transdermal patches
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58. 2. The progestasert system
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59. 3. Occusert system
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60. In Matrix System
• The drug is homogenously dispersed either at a
molecular scale or as solid particles within a
polymeric medium.
• Examples of polymers used as cellulose derivatives
like HPMC, sod.CMC, PVP, Polyurethane etc.
• Swelling Controlled Release System
• It is assumed that the shape and dimensions of the
devices do not change during the course of drug
release .
• Hydrophobic nature of the polymers are used .
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61. APPLICATIONS IN NDDS
Osmotic pressure controlled GI delivery
 Semi permeable membrane made from bio compatible
polymers are used
 For example, Acutrim tablet which contain phenyl
propanolamine as a drug and cellulose acetate as a
polymer
 Gel diffusion controlled GI delivery systems
 It is fabricated from gel forming polymers such as
CMC
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62. Bio adhesive GI drug delivery system
It is capable of producing an adhesion interaction
with a biological membrane
Eg ;Carbopol
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63. CONTINUES…
•Lactic acid and glycolic acids are widely used in drug
delivery research due to their versatility in
polymer properties.
•Poly-anhydrides are used in CDDS because of their
unique property of surface erosion.
•Poly-caprolactone is used with other polymers in
designing CDDS.
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64. •Poly-phosphazenes are used in the
formulation of Melfalan matrix systems.
•Pseudo-amino acids are used in controlled
release formulations
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65. •Hyaluronic acid is used in controlled release
ophthalmic preparations.
•Poly-ortho esters are used in developing
implants and oral CDDS.
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66. 66

67. References:
 Controlled and novel drug delivery – N.K Jain. CBS
Publishers and distributors, New Delhi
 Novel drug delivery system- Y.W. Chien. Marcel
Dekkar,inc. New york, 1992
 D.jone. Pharmaceutical Applications of Polymers for
Drug delivery. Volume 15, 2006
 Darveshwar, Mule madhav. Review on applications
on polymers in pharmaceutical formulations.
Pharmatutor-art-1059
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68. THANK YOU
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