Slide 1: POLYMERS USED IN DRUG DELIVERY SYSTEM
B. Vamsikrishna Reddy
M.Pharm first year,
firstname.lastname@example.org 1 Contents : Contents Introduction
Mechanism of degradation
References 2 Introduction : Introduction Significant advances have been made in the development of various drug delivery devices with the help of polymers.
They have better physical, chemical& biological properties for efficient therapy. 3 DEFINITION : DEFINITION Polymers are defined as very large macromolecules consisting of repeating units of monomers.
The monomers can be linked together to generate a linear polymer.
Two types of polymers are there:
1 )Linear&Branched polymers .
2) Cross linked polymers. 4 Slide 5: 5 Polymer degradation : Polymer degradation Degradation of polymer is primarily the process of chain cleavage leading to reduction of molecular weight.
Erosion is the sum of all processes leading to loss of polymer matrix.
Degradation is either through bulk erosion and surface erosion. 6 Classification of polymers : Classification of polymers 1.Based on method of polymerisation
a) Addition polymers
b) Condensation polymers
c) Chain polymerization. 7 Conti.. : Conti.. 2. Based on degradability of polymers
Non biodegradable polymers
Environment responsive polymers 8 Biodegradable polymers : Biodegradable polymers Natural polymers- Collagen
Modified natural polymers- Dextrin
Synthetic polymers (aliphatic poly esters)
Polyglycolic acid and its copolymers
Polylactic acid and its copolymers
Polycaprolactone and its copolymers
Polyphosphazene 9 Non biodegradable polymers : Non biodegradable polymers Hydrophilic polymers- HPMC
Ethyl cellulose,silicones 10 Environment responsive polymers : Environment responsive polymers Thermosensitive polymers
Electrically and Chemically controlled polymers
pH sensitive polymers 11 Natural and modified natural polymers : Natural and modified natural polymers Natural polymers are proteins and polysaccharides chemically.
Natural polymers modified either by chemical means or enzymatically are termed as modified natural polymers. 12 Collagen : Collagen Advantages of using the collagen:
Easy to isolate and purify in large quantities.
Biocompatible and non toxic profile.
Well established physiochemical, structural and immunological properties. 13 Conti… : Conti… Disadvantages of collagen
Residual aldehyde cross linking agents
Chances of trigering antigenic responses
Poor mechanical strength
Non reproducible delivery rates 14 Albumin : Albumin Advantages are:
Biodegradation into natural products
Absence of toxicity and antigenicity 15 Gelatin : Gelatin Physiochemical properties of gelatin depends on :
Source of collagen
Thermal degradation and pH value
Electrolyte content 16 Gelatin (contd) : Gelatin (contd) Advantages are:
Low antigen profile
Low temperature preparation technique
Poor binding to drug molecules 17 Contd: : Contd: Properties of gelatin:
Colloid and emulsifying property. 18 Chitosan : Chitosan Properties that render them suitable:
a. Have pharmacological properties like antiulcer.
b. Heamostatic property due to polycationic character.
c. Gel forming ability at low pH.
d. Favourable biological properties. 19 Synthetic polymers : Synthetic polymers Synthesized by two methods
a) Poly condensation of bi-functional hydroxyl acids
b) Ring opening & Polymerisation of cyclic ester monomers. 20 Poly glycolic acid: : Poly glycolic acid: Highly crystalline polymer and low solubility in organic solvents.
Simplest linear aliphatic ester.
Non toxic ,biocompatible.
Rate of hydration is increased by increasing glycollic acid concentration in copolymer. 21 Lactide&glycolide ratios(co polymer) : Lactide&glycolide ratios(co polymer) polymer Degradation time
(in months) DL- L/G (85:15)
DL- L/G (25:75)
DL-L/G (50:50) 5-6
1-2 22 Slide 23: 23 Polyphosphoesters : Polyphosphoesters Has a unique backbone consisting of phosphorous atom attached either to carbon or oxygen
Chemical reactivity results in uniqueness of the class
Biocompatibility 24 Slide 25: 25 Slide 26: 26 NON BIODEGRADABLE POLYMERS : NON BIODEGRADABLE POLYMERS Ethyl Cellulose-Hydrophobic polymer
1.Coating of solid dosage forms, in matrix systems which are prepared by wet granulation or direct compression or in micro encapsulation.
2.Excellent film forming properties.
3.Tasteless and odorless, physiologically inert.
4. Stable in pH range of 3 and 11.
5.Nonionic character 27 Hydrophilic polymers : Hydrophilic polymers Ex: HPMC
The physicochemical properties of this substance of this strongly depend on the following:
Molecular weight 28 ENVIRONMENT RESPONSIVE POLYMERS : ENVIRONMENT RESPONSIVE POLYMERS 1) Thermosensitive polymers:
Temperature modulation of polymeric
device is needed in these cases:
a) Hyperpyretic drug delivery
b) Transdermal delivery system
c) Externally modulated devices 29 pH sensitive polymers: : pH sensitive polymers: 1) Acidic group and swells in basic pH,
2) Basic group and swells in acidic pH
Employs enzymes or antibodies to produce pH change.
This pH change modifies its erosion rate. 30 RECENT POLYMERS : RECENT POLYMERS DENDRIMERS:
Ideal candidates among model hyperbranched polymers because of their well-defined structure and high density of functional groups.
Use of such nano-structured systems for targeted drug delivery is being explored. This may be achieved by attaching ligands or antibodies to the surface groups, and using the multivalency effect to improve targetabilty. Proposed structure of drug/dendrimer complex with targeting moiety may look as shown in figure. 31 Structure of dendrimer : Structure of dendrimer 32 Uses of polymers : Uses of polymers 33 AS GENE CARRIER: : AS GENE CARRIER: 34 CONCLUSION- : CONCLUSION- The knowledge and skill in area of biodegradable polymer technology is expanding rapidly.
This cutting edge technology has generated a substantial number of biodegradable polymers with wide range of degradation rates.
This has widened the horizon of the options that researchers have at their disposal for controlled and targeted delivery of a whole array of therapeutic moieties. 35 REFERENCES: : REFERENCES: Biodegradable polymers as Drug Delivery system, edited by Mark Chasin, Robert Langer Volume 45
Controlled Drug Delivery by S.P.Vyas, page no- 97-155
Biodegradable polymers as biomaterials -Lakshmi S. Naira, Cato T. Laurencin
Gelatin as a delivery vehicle for the controlled release of bioactive molecules- Simon Young , Mark Wong , Yasuhiko Tabata , Antonios G. Mikos-- Journal of Controlled Release 109 (2005) 256– 274
Polymers in drug delivery -Omathanu Pillai and Ramesh Panchagnula Department of Pharmaceutics, National Institute of
Pharmaceutical Education & Research (NIPER)
Polymeric biomaterial-L. G. GRIFFITH, Massachusetts Institute of Technology, Acta mater. 48 (2000) 263±277
Rationalizing the design of polymeric biomaterials- Nela Angelova and David Hunkeler 36 Thank you : Thank you 37