Biodegradable polymers can be used for controlled drug release applications. They degrade in the body through natural processes and produce non-toxic byproducts. Synthetic biodegradable polymers commonly used include PLA, PGA and PLGA. Drug release from polymers occurs through mechanisms like swelling, erosion and degradation. Biodegradable polymers find applications in drug delivery systems like implants, microparticles and hydrogels. Hydrogels are three-dimensional polymer networks that can absorb large amounts of water and are useful for controlled drug delivery.

1. STUDY OF BIODEGRADABLE POLYMERS
FOR CONTROLLED RELEASE
K.SENTHIL KUMAR
Asst.Professor
Department of Pharmaceutics
QIS College Of Pharmacy,ongole,AP-523272.

2.  Polymer is a large molecule or macromolecule composed of
many smaller units called monomers that are bonded together.
 The term polymer is a Greek word which means (poly =
many" and mer means "part")
 Commonly referred as plastics.
Polymer used as a pharmaceutical excipients in drug delivery
system

3. • Biodegradable polymers can be defined as polymers that are degradable in vivo, either
enzymatically or non-enzymatically, to produce biocompatible or nontoxic by-products.
• These polymers can be metabolized and excreted through normal physiological pathways.
• They are classified into three groups, namely synthetic, semi synthetic and natural,
based on their sources.
• Biodegradation is a natural process by which organic chemicals in the environment are
converted to simpler compounds, mineralized and redistributed through elemental cycles
such as the carbon(C), nitrogen (N) and sulphur (S) cycles.
• Polymers have been used as a main tool to control the drug release rate from the
formulations.

4. Characteristics of Ideal Polymer
• Should be inert and compatible with the environment.
• Should be non-toxic.
• Should be easily administered.
• Should be easy and inexpensive to fabricate.
• Should have good mechanical strength

5. Advantage of biodegradable polymers:
 It provides a drug at a constant rate of controlled
release
 Nontoxic
 Biocompatible

6. CLASSIFICATION OF BIODEGRADABLE POLYMERS
a) Natural Polymers :
i) Proteins
Ex : albumin, collagen and gelatin
ii) Polysaccharides
• Ex : dextran, starch,cyclodextrin,pullulan, Schizophyllan(produced by fungus of the
genus Schizophyllum),Xanthan gum ,guargum ,gellan gum
• Polysaccharides can be positively charged (chitosan) or negatively charged
(alginate,heparin, hyaluronic acid, pectin,.

7. SEMI-SYNTHETIC:
• Hydroxy Propyl Methyl Cellulose (HPMC),
• Methyl Cellulose (MC),
• Hydroxy Propyl Cellulose (HPC)

8. • Poly(methyl methacrylate)- PMMA
• Poly(vinyl alcohol)- PVA
• Poly(vinyl pyrrolidone)PVP
• Poly(acrylic acid)PAA
• Polyacrylamide. PA
• Poly(ethylene glycol).PEG
• Poly(methacrylic acid).PMA
• Polylactides (PLA).
• Polyglycolides (PGA)
• Poly(lactide-co-glycolides) (PLGA)
• Polyanhydrides
• Polyorthoesters
• Poly (E-caprolactone) PCL
SYNTHETIC BIODEGRADABLE POLYMERS

9. NON BIODEGRADABLE POLYMERS
• Polyethylene terephthalate, or PET
• Poly(ethylene)- PE
• Polypropylene -PP

10. Factors Influence the Polymer Degradation
• Chemical Structure and its Composition of polymer
• Distribution of Repeat Units in Multimers
• Molecular Weight of polymer
• Physiochemical factors of polymer (shape, size)
• Mechanism of Hydrolysis (enzymes vs water)
• Configurational Structure
• Sterilization process
• Site of implantation.
• Morphology (amorphous/semicrystalline).
• Processing conditions.
• Storage history
• Presents of ionic groups.

11. • Controlled drug delivery occurs when a polymer, whether natural or
synthetic, is judiciously combined with a drug or other active agent in
such a way that the active agent is released from the material in a
predesigned manner.
• Controlled-release methodologies can be classified on the basis of the
mechanism that controls the release of the active agent from the
delivery device diffusion, osmosis, or polymer erosion.

12. MECHANISM OF DRUG RELEASE FROM
POLYMERS
• Swelling mechanism
They are initially dry and when placed in the body will absorb water or other
body fluids and swell. The swelling increases the aqueous solvent content
within the formulation as well as the polymer mesh size, enabling the drug to
diffuse through the swollen network into the external environment.
• Erosion mechanism
The physical erosion mechanisms can be characterized as heterogeneous or homogeneous. In
heterogeneous erosion, also called as surface erosion, the polymer erodes only at the surface,
and maintains its physical integrity as it degrades. As a result drug kinetics is predictable, and
zero order release kinetics can be obtained. Most polymers undergo homogeneous erosion,
means the hydrolysis occurs at even rate throughout the polymeric matrix.

14. • Degradation -Most biodegradable polymers are designed to degrade
as a result of hydrolysis of the polymer chains into biologically
acceptable .
• Diffusion- occurs when a drug or other active agent passes through
the polymer that forms the controlled‐release device. Diffusion
occurs when the drug passes from the polymer matrix into the
external environment.

15. BIODEGRADABLE POLYMER APPLICATIONS
1. Coated tablet preparation
2. Capsules preparation(as diluents)
3. Disperse Systems
4. Gels,jellies,implant,ocusert,in situ gel, contact lense.
5. Transdermal Drug Delivery Systems (Patches)
6. Preparation of pellet ,Nanocarriers ,microparticle, taste masking
etc.
7. Buccal tablet,buccal patch,parenteral product,osmotic
tablet,floating tablet,colonic tablet,

16. • The perfection of such systems can be used to grow tissues and cells in
vitro or use a biodegradable scaffold to construct new structures and
organs in vitro.
• biodegradable polymers are being used orthopedic applications, such as
bone and joint replacement.(USED AS CEMENT)
• EG. hyaluronic acid have been used extensively in the repair of cartilage,
ligaments, and tendons
GENERAL APPLICATION OF BIODEGRADABLE POLYMERS

17. • biodegradable materials play an important role in dental or maxillofacial
surgery above all for bone regeneration and periodontal disease
• In medicine, a stent is any device which is inserted into a blood
vessel or other internal duct to expand it to prevent or alleviate a
blockage
biodegradable stent or naturally-dissolving stent

18. TISSUE ENGINEERING
biodegradable polymers and their composites as materials for controlled-release of
agrochemicals in soil
Cellulose, natural gum, rosin, waxes

19. .
Scaffold plays a unique role in tissue regeneration and repair

20. HYDROGEL
Hydrogels were first reported by Wichterle and Lím (1960)

21. A hydrogel is a three-dimensional (3D) network of hydrophilic polymers
that can swell in water and hold a large amount of water while
maintaining the structure due to chemical or physical cross-linking of
individual polymer chains.
 Hydrogels can be physical, chemical, or biochemical. Physical gels can undergo a
transition from liquid to a gel in response to a change in environmental conditions
such as temperature, ionic concentration, pH, or other conditions such as mixing of
two components.
 Chemical gels use covalent bonding that introduces mechanical integrity and
degradation resistance compared to other weak materials.
 In biochemical hydrogels, biological agents like enzymes or amino acids participate in
the gelation process.

22. • Hydrogels are polymeric materials that do not dissolve in water at
physiological temperature and PH but swell considerably in aqueous
medium.
• Hydrogels are of special interest in controlled release applications because
of their safe tissue biocompatibility, the case with which the drugs are
dispersed in the matrix and the high degree of control achieved by selecting
the physical and chemical properties of the polymer network.
HYDROGELS

23. HYDROGELS
• Hydrogels consist of polymer chains cross – linked to each other to
create a tangled mush structure, providing a matrix for the Entrapment
of drugs. These properties conducted a considerable research on
hydrogels and their usage in controlled release technology.

24. Classification of hydrogels
On the basis of route of their synthesis
1. Homopolymer hydrogels (made up of only one type of
hydrophilic monomer)
2. Copolymer hydrogels or network gels (composed of two types
of monomers)
3. Mutipolymer hydrogels (made up of three types of monomers
or inter penetrating polymeric network)

25. on the basis of type of ionic charges present on polymer networks
•Anionic hydrogels (anionic thermos associative
carboxy methyl pullulanhydrogels )
•Cationic hydrogels (new thermos sensitive gel)

26. on the basis of physical structures hydrogels
• Amorphous hydrogels
• Semi crystalline hydrogels
On the basis of Smart Hydrogel
• pH Acidic or basic hydrogel Change in pH—swelling—release of drug
• Ionic Strength Ionic hydrogel Change in ionic strength—change in concentration of ions inside
the gel—
change in swelling—release of drug.
• Thermal Thermo-responsive hydrogel Change in temperature—change in polymer–polymer and
water–
polymer interactions—change in swelling—release of drug

27. POLYMERS USED FOR HYDROGEL PREPARATION
• Poly (lactic –glycolic acid)
• Hydroxyethyl cellulose
• Starch
• Chitosan
• Sodium alginate
• Xanthan gum, pectin
• Gellan gum ,locust gum
• Guargum
• Carbopol

28. APPLICATIONS OF HYDROGEL
• Colon Specific Hydrogels: Colon specific hydrogels of polysaccharide have
been specifically designed because of presence of high concentration of
polysaccharide enzymes in the colon region of GI.
• Drug delivery in GI tract - hydrogels delivers drugs to specific site in the
GIT.
• Modified Dosage Forms: An interesting research in the field of drug
delivery is of bio- macromolecules like insulin delivered to the site of
absorption with hydrogel

29. • Rectal Delivery – hydrogels showing bioadhesive properties are used for
rectal drug delivery.
• Protein drug delivery – hydrogels which show better complicance and form
in situ polymeric network and release protein slowly.
• Transdermal delivery – hydrogels can be used as controlled release devices
in the filed of wound dressing due to it swelling properties. Hydrogel based
formulations are being explored for transdermal iontophoresis to obtain
enhanced permeation of products

30. • Subcutaneous delivery – anticancer drugs are mainly used for the
subcutaneous delivery.
• Gene delivery – change in composition of hydrogels leads to effective
targeting and delivery of nuclei acids to specific cells for gene therapy.
• Tissue Engineering – micronized hydrogels are used to deliver
macromolecules into cytoplasm of antigen presenting cells.