Presented By: SANDEEP MOLLIDAINM.Pharmacy (pharmaceutical technology)Dept. of pharmaceutical technology.Vsp.
CONTENTS
•Introduction•Classification of Hydrogels•Advantages of Hydrogels•Disadvantages of Hydrogels•Types of Hydrogels •Monomers Used In The Synthesis of Synthetic Hydrogels•Method of Preparation of Hydrogels•Characterization of Hydrogels•Common Uses For Hydrogels•Pharmaceutical Applications of Hydrogels•Summary and conclusions•References•Acknowledgement
2
Introduction:
Hydrogel is a network of polymer chains that are
hydrophilic, water insoluble, sometimes found as a
colloidal gel in which water is the dispersion medium.
Hydrogels are highly absorbent natural or synthetic
polymers.
Definition:
3
Introduction:
Hydrogels are crosslinked polymer networks that absorb
substantial amounts of aqueous solutions.
Hydrogels can contain over 99.9% water.
Hydrogels are three-dimensional, hydrophilic, polymeric
networks capable of imbibing large amounts of water or
biological fluids.
4
Introduction:
The networks are composed of homopolymers or
copolymers, and are insoluble due to the presence of
chemical crosslinks (tie-points, junctions), or physical
crosslinks, such as entanglements or crystallites.
The high water content of the materials contributes to
their biocompatibility.
5
Introduction:
These crosslinks provide the network structure and
physical integrity.
These hydrogels exhibit a thermodynamic
compatibility with water which allows them to swell in aqueous media.
6
Classification Of Hydrogels:
7
Advantages of Hydrogels :
Hydrogels possess a degree of flexibility very similar
to natural tissue, due to their significant water content.
Entrapment of microbial cells within Hydrogel
beads has the advantage of low toxicity.
Environmentally sensitive Hydrogels have the
ability to sense changes of pH, temperature, or the
concentration of metabolite and release their load as
result of such a change.8
Advantages of Hydrogels:
Timed release of growth factors and other nutrients
to ensure proper tissue growth.
Hydrogels have good transport properties.
Hydrogels are Biocompatible.
Hydrogels can be injected.
Hydrogels are easy to modify.
9
Disadvantages of Hydrogels:
Hydrogels are expensive.
Hydrogels causes sensation felt by movement of the maggots.
Hydrogels causes thrombosis at Anastomosis sites.
The surgical risk associated with the device implantation and retrieval.
Hydrogels are non-adherent; they may need to be secured by a secondary dressing.
Hydrogels are expensive.
Hydrogels causes sensation felt by movement of the maggots.
Hydrogels causes thrombosis at Anastomosis sites.
The surgical risk associated with the device implantation and retrieval.
Hydrogels are non-adherent; they may need to be secured by a secondary dressing.
10
Disadvantages of Hydrogels:
Hydrogels used as contact lenses causes lens
deposition,hypoxia, dehydration and red eye
reactions.
Hydrogels have low mechanical strength
Difficulty in handling.
Difficulty in loading.
Difficulty in Sterilization11
Types of Hydrogels :
Natural Polymers
e.g.: Dextran, Chitosan, Collagen, Dextran Sulfate
Disadvantages:
Low mechanical Strength.
Batch variation.
Animal derived materials may pass on viruses.12
Types of Hydrogels :
Synthetic Polymers
e.g.:Poly (vinyl alcohol)
Disadvantages:
Low biodegradability
Can include toxic substances
13
Hydrogels can be used in different types of controlled release systems.
These are classified according to the mechanism controlling the release of drug from the device as
- Diffusion controlled systems.- Swelling controlled system.- Chemically controlled system.- Environmental responsive systems.
Classification Of Hydrogel Based Systems:
14
Diffusion is the most common mechanism controlling release.
In hydrogel based drug delivery system. There two types : -Reservoir devices. -Matrices devices
Diffusion is the most common mechanism controlling release.
In hydrogel based drug delivery system. There two types : -Reservoir devices. -Matrices devices
Diffusion Controlled Release Systems:
15
Reservoir devices:
They consists of polymeric membrane surrounding a core containing a drug .
Typically reservoir devices are capsules, cylinders, slabs or spheres.
Rate limiting step for drug release is diffusion through the outer membrane of the device.
Reservoir devices:
They consists of polymeric membrane surrounding a core containing a drug .
Typically reservoir devices are capsules, cylinders, slabs or spheres.
Rate limiting step for drug release is diffusion through the outer membrane of the device.
Diffusion Controlled Release Systems:
16
Draw backs:
In the event that the outer membrane ruptures the entire content of the device are delivered instantaneously .
While preparing these device care must taken to ensure that the device doesn't contain pin holes or defects that may lead to rupture.
Draw backs:
In the event that the outer membrane ruptures the entire content of the device are delivered instantaneously .
While preparing these device care must taken to ensure that the device doesn't contain pin holes or defects that may lead to rupture.
Diffusion Controlled Release Systems:
17
Matrix devices:
In matrix devices the drug is dispersed through out the 3D structure of the hydrogel.
Release occur due to diffusion of the drug through out the macro molecular mesh or water filled pores.
Matrix devices:
In matrix devices the drug is dispersed through out the 3D structure of the hydrogel.
Release occur due to diffusion of the drug through out the macro molecular mesh or water filled pores.
Diffusion Controlled Release Systems:
18
In these release drug systems the drug is dispersed within a glassy polymer .
Up on contact with biological fluid, the polymer begins to swell.
As the penetrant enters the glassy polymer, the glass transition temperature of the polymer is lowered allowing for relaxations of the macro molecular chains.
Swelling Controlled Release Systems:
19
They are of two types:
Erodible drug delivery system -In erodible system drug release occurs due to
degradation or dissolution of the hydrogel.
Pendent chain system -In pendent chain system drug is affixed to the
polymer back bone through degradable linkages. -As these linkages degrade drug is released
They are of two types:
Erodible drug delivery system -In erodible system drug release occurs due to
degradation or dissolution of the hydrogel.
Pendent chain system -In pendent chain system drug is affixed to the
polymer back bone through degradable linkages. -As these linkages degrade drug is released
Chemically Controlled Release Systems
20
It is also known as degradable or absorbable release system, can be either matrix or reservoir type.
In reservoir type devices the membrane erodes significantly and drug is released by diffusion mechanism.
Zero order release can be obtained by this system.
It is also known as degradable or absorbable release system, can be either matrix or reservoir type.
In reservoir type devices the membrane erodes significantly and drug is released by diffusion mechanism.
Zero order release can be obtained by this system.
Erodible Drug Delivery System
21
This system consists of linear homo/co-polymers with drug attached to the back bone chains.
The drug is released from the polymer by hydrolysis or enzymatic degradation of these linkages.
This system consists of linear homo/co-polymers with drug attached to the back bone chains.
The drug is released from the polymer by hydrolysis or enzymatic degradation of these linkages.
Pendent Chain System
22
Stimuli-sensitive Swelling-controlled Release Systems
Environmentally-sensitive hydrogels have the ability
to respond to changes in their external environment.
They exhibit dramatic changes in their swelling
behavior, network structure, permeability or
mechanical strength in response to changes in the
pH or ionic strength of the surrounding biological
fluid, or temperature.
Environmentally-sensitive hydrogels have the ability
to respond to changes in their external environment.
They exhibit dramatic changes in their swelling
behavior, network structure, permeability or
mechanical strength in response to changes in the
pH or ionic strength of the surrounding biological
fluid, or temperature. 23
Stimuli-sensitive Swelling-controlled Release Systems
Other hydrogels have the ability to respond to
applied electrical or magnetic fields, or to changes
in the concentration of glucose.
Because of their nature, these materials can be used
in a wide variety of applications, such as separation
membranes, biosensors, artificial muscles, chemical
valves and drug delivery devices.24
pH-Sensitive Hydrogels:
Hydrogels exhibiting pH-dependent swelling
behavior contain ionic networks contain either
acidic or basic groups.
In aqueous media of appropriate pH and ionic
strength, these groups ionize, and develop fixed
charges on the gel.
Hydrogels exhibiting pH-dependent swelling
behavior contain ionic networks contain either
acidic or basic groups.
In aqueous media of appropriate pH and ionic
strength, these groups ionize, and develop fixed
charges on the gel.
25
pH-Sensitive Hydrogels:
As a result of the electrostatic repulsions, the
uptake of solvent in the network is increased.
Ionic groups, such as carboxylic or sulfonic acid, show sudden or gradual changes in their dynamic
and equilibrium swelling behavior as a result of
changing the external pH.
26
pH-Sensitive Hydrogels:
In these gels, ionization occurs when the pH of the
environment is above the pKa of the ionizable group.
As the degree of ionization increases (increased
system pH), the number of fixed charges increases,
resulting in increased electrostatic repulsions between
the chains.
This, in turn, results in an increased hydrophilicity of
the network, and greater swelling ratios. 27
pH-Sensitive Hydrogels:
Conversely, cationic materials contain groups such as amines.
These groups ionize in media which are at a pH below the pKb of the ionizable species.
Thus, in a low pH environment, ionization increases, causing increased electrostatic repulsions.
The hydrogel becomes increasingly hydrophilic and will swell to an increased level.
28
Temperature-sensitive Hydrogels:
Temperature-sensitive hydrogels have gained considerable attention due to the ability of the hydrogels to swell or deswell as a result of changing the temperature of the surrounding fluid.
Widely used in on±off drug release regulations, biosensors and intelligent cell culture dishes.
29
Temperature-sensitive Hydrogels:
Thermosensitive hydrogels can be classified as
positive or negative temperature-sensitive systems.
A positive temperature-sensitive hydrogel has an
upper critical solution temperature (UCST).
Such hydrogels contract upon cooling below the
UCST.
30
Temperature-sensitive Hydrogels:
Negative temperature-sensitive hydrogels
have a lower critical solution temperature (LCST).
These hydrogels contract upon heating above the
LCST.
31
Other Stimuli-sensitive Hydrogels:
Several stimuli, other than pH and temperature, can
trigger drug release from a depot.
These include physical stimuli, such as light,
magnetic field , electric current and ultrasound ,
which can be applied to the systems externally.
Chemical stimuli, like ionic species , certain
chemical substances and biological compounds.
Several stimuli, other than pH and temperature, can
trigger drug release from a depot.
These include physical stimuli, such as light,
magnetic field , electric current and ultrasound ,
which can be applied to the systems externally.
Chemical stimuli, like ionic species , certain
chemical substances and biological compounds.
32
Monomer abbreviation
Monomer
HEMA Hydroxyethyl methacrylate
HEEMA Hydroxyethoxyethyl methacrylate
HDEEMA Hydroxydiethoxyethyl methacrylate
MEMA Methoxyethyl methacrylate
MEEMA Methoxyethoxyethyl methacrylate
Monomers Used In The Synthesis Of Synthetic Hydrogels:
33
Monomer abbreviation
Monomer
EG Ethylene glycol
EGDMA Ethylene glycol dimethacrylate
NVP N-vinyl-2-pyrrolidone
AA Acrylic acid
PEGMA PEG methacrylate
Monomers Used In The Synthesis Of Synthetic Hydrogels:
34
Method Of Preparation Of Hydrogels:Crosslinking
Isostatic Ultra High Pressure
Nucleophilic Substitution Reaction
Using Gelling Agents
Use Of Irradiation
Freeze Thawing 35
Crosslinking:
Linear polymers
Crosslinking
Chemical compoundsIrradiation
Monomers used in the preparation of the ionic polymer network contain an ionizable group, gets ionized, or undergoes substitution after the polymerization is completed.
36
By using Cross Linkers:
Purpose To impart sufficient mechanical strength to these polymers
Examples
Cross linkers prevent burst release of the medicaments.
Glutaraldehyde, Calcium chloride
Presence of residue.
Advantage
Drawbacks
37
Isostatic Ultra High Pressure :
Suspension of natural biopolymers (starch)
ultrahigh pressure of 300-700 MPa
5or 20 min
gelatinization of starch molecules occur.
IUHP brings about changes in the morphology of the polymer.Where as heat-induced gelatinization (40 to 52°C) causes a change in ordered state of polymer.
38
Nucleophilic Substitution Reaction:
Methacyloyl chloride 2-dimethylamino ethylamine.
Nucleophilic substitution.
N-2-dimethyl amino ethyl-methacryalmide (DMAEMA)
(a pH and temperature sensitive.)
39
By Using Gelling Agents:
Examples
Glycophosphate. 1-2 Propanediol.Glycerol. Mannitol.
Drawbacks
Turbidity. Presence of negative charged moieties pose problem of interaction with the drug.
40
Use Of Irradiation:
Irradiation method processing is costlyMechanical strength of such Hydrogels is less.
Advantages
Drawbacks
Irradiation method is convenient. Hydrogels prepared by microwave irradiation are more porous than conventional methods.
41
Freeze Thawing:
Opaque in appearance
Little swelling capacity.
Advantage
Drawbacks
Sufficient mechanical strength.
Good Stability.
42
Characterization Of Hydrogels:
43
Atomic Force Microscope
Atomic Force Microscopy (AFM):
A Multimode Atomic Force Microscope form Digital Instrument is used to study the surface morphology of the hydrogels.
44
X-ray Diffraction:
Used to understand whether the polymers retain their crystalline structure or they get deformed during the pressurization process
45
FTIR (Fourier Transform Infrared Spectroscopy)
Any change in the morphology of Hydrogels changes their IR absorption spectra.
Formation of coil or helix which is indicative of cross linking is evident by appearance of bands near 1648 cm-1
FTIR
46
Rheology:
Hydrogels are evaluated for viscosity under constant temperature (4°C) by using Cone Plate viscometer.
Cone plate viscometer47
Swelling Behavior:
The Hydrogels are allowed to immerse in aqueous
medium or medium of specific pH to know their
swellability. of these polymeric networks.
These polymers show increase in dimensions related
to swelling.
48
Swelling degrees (SDs) of hydrogels were measured
at 370 C. The fresh made samples (wet) were weighted
and immersed in buffer solutions with different pH
values. These samples were gently wiped with filter
paper to remove the surface solution when taken out
from the solutions, then weighted and returned to the
Same container at pre-determined time intervals.
Swelling Behavior:
49
Swelling Behavior:
The SD was calculated as follows:
W0 = Weight of the original Hydrogel
Wt = is the weight of hydrogel at various swelling times
SD (%)= (Wt/Wo)×100
Picture of a swollen Hydrogel50
In-vitro Release Study For Drugs:
Since Hydrogels are the swollen polymeric networks,
interior of which is occupied by drug molecules,
therefore, release studies are carried out to understand
the mechanism of release over a period of application
51
In-vitro Release Study For Drugs:
Dissolution media: Buffer solution with various pH values.
R.P.M: 90 rpm.
Temperature : 370C.
Sink condition is maintained by replacing the buffer periodically.
Dissolution apparatus
52
Physical, Chemical And Toxicological Properties Of Hydrogels:
Factors affecting swelling of hydrogels.
Mechanical properties.
Cytotoxicity and in-vivo toxicity.
53
Factors Affecting Swelling Of Hydrogels:
It is defined as the ratio of moles of crosslinking
agent to the moles of polymer repeating units.
The higher the crosslinking ratio, the more
crosslinking agent is incorporated in the hydrogel
structure.
Crosslinking ratio
54
Factors Affecting Swelling Of Hydrogels:
Highly crosslinked hydrogels have a tighter
structure, and will swell less compared to the same hydrogels with lower crosslinking ratios.
Crosslinking hinders the mobility of the polymer
chain, hence lowering the swelling ratio.
Crosslinking ratio
55
Factors Affecting Swelling Of Hydrogels:
The chemical structure of the polymer may also
affect the swelling ratio of the hydrogels.
Hydrogels containing hydrophilic groups swell to a
higher degree compared to those containing
hydrophobic groups..
Chemical Structure
56
Factors Affecting Swelling Of Hydrogels:
Hydrophobic groups collapse in the presence of
water, thus minimizing their exposure to the water
molecule.
As a result, the hydrogels will swell much less
compared to hydrogels containing hydrophilic
groups.
Chemical Structure
57
Factors Affecting Swelling Of Hydrogels:
Swelling of environmentally-sensitive hydrogels
can be affected by specific stimuli.
Swelling of temperature-sensitive hydrogels can be
affected by changes in the temperature of the
swelling media.
Chemical Structure
58
Factors Affecting Swelling Of Hydrogels:
Ionic strength and pH affect the swelling of ionic
strength- and pH-sensitive Hydrogels, respectively.
There are many other specific stimuli that can affect the swelling of other environmentally-responsive
Hydrogels.
Chemical Structure
59
Mechanical properties:
Mechanical properties of hydrogels are very
important for pharmaceutical applications.
The integrity of the drug delivery device during
the lifetime of the application is very important to
obtain FDA approval, unless the device is
designed as a biodegradable system.
60
Mechanical properties:
A drug delivery system designed to protect a
sensitive therapeutic agent,such as protein, must
maintain its integrity to be able to protect the protein
until it is released out of the system.
Changing the degree of crosslinking has been
utilized to achieve the desired mechanical property
of the hydrogel.
61
Mechanical properties:
Increasing the degree of crosslinking of the system
will result in a stronger gel.
However, a higher degree of cross-linking creates a
more brittle structure.
Hence, there is an optimum degree of crosslinking
to achieve a relatively strong and yet elastic
hydrogel. 62
Mechanical properties:
Copolymerization has also been utilized to achieve
the desired mechanical properties of hydrogels.
Incorporating a co-monomer that will contribute
to H-bonding can increase the strength of the
hydrogel.
63
Cytotoxicity And In-vivo Toxicity:
Cell culture methods, also known as cytotoxicity
tests, can be used to evaluate the toxicity of
hydrogels.
Three common assays to evaluate the toxicity of
hydrogels include
-extract dilution. -direct contact.-agar diffusion.
64
Cytotoxicity And In-vivo Toxicity:
Most of the problems with toxicity associated with
hydrogel carriers are the unreacted monomers, oligomers and initiators that leach out during application.
So, a good understanding the toxicity of the
monomers and initiators used is very important.
65
Cytotoxicity And In-vivo Toxicity:
Approaches to solve this problem:
Modifying the rate of polymerization in order to
achieve a higher conversion
Extensive washing of the resulting hydrogel.
Formation of hydrogels without any initiators to
eliminate the problem of the residual initiator.
66
Cytotoxicity And In-vivo Toxicity:
Commonly used technique to eliminate the problem
of the residual initiator is by using gamma irradiation.
Hydrogels can be made without the presence of
initiators by using thermal cycle to induce
crystallization. The crystals formed act as physical
crosslinks and are able to absorb the load applied to
the hydrogels.
Commonly used technique to eliminate the problem
of the residual initiator is by using gamma irradiation.
Hydrogels can be made without the presence of
initiators by using thermal cycle to induce
crystallization. The crystals formed act as physical
crosslinks and are able to absorb the load applied to
the hydrogels.67
Common Uses For Hydrogels:
68
Pharmaceutical Applications Of Hydrogels:
Peroral Drug Delivery
Drug Delivery In The Oral Cavity
Drug Delivery in the G.I.T
Ocular Delivery
Transdermal Delivery
Subcutaneous Drug Delivery
Hydrogels To Fix Bone Replacements
Tissue Engineering
Protein Drug Delivery
Topical Drug Delivery
69
Drug delivery through the oral route has been the
most common method in the pharmaceutical
applications of hydrogels.
In peroral administration, hydrogels can deliver
drugs to four major specific sites; mouth, stomach,
small intestine and colon.
Peroral Drug Delivery:
70
By controlling their swelling properties or
bio-adhesive characteristics in the presence of a
biological fluid, hydrogels can be a useful device
for releasing drugs in a controlled manner at these
desired sites.
Peroral Drug Delivery:
71
Additionally, they can also adhere to certain specific
regions in the oral pathway, leading to a locally increased drug concentration, and thus, enhancing
the drug absorption at the release site.
Peroral Drug Delivery:
72
Drug delivery to the oral cavity can have versatile
applications in local treatment of diseases of the
mouth, such as periodontal disease, stomatitis,
fungal and viral infections,and oral cavity cancers.
Long-term adhesion of the drug containing hydrogel
against copious salivary flow, which bathes the oral
cavity mucosa, is required to achieve this local drug
delivery.
Drug Delivery In The Oral Cavity:
73
Drug Delivery in the G.I.T:
Ease of administration of drugs. Availability of large surface area for drug absorption
High patient compliance.
First pass metabolism.
Pre-systemic metabolism.
Advantages with oral route
Drawbacks with oral route
74
Drug Delivery in the G.I.T:
Hydrogel-based devices can be designed to deliver
drugs locally to specific sites in the GI tract. E.g.,: Specific antibiotic drug delivery systems for the
treatment of H.pylori infection in peptic ulcer disease
These Hydrogels protect the insulin in the harsh, acidic
environment of the stomach before releasing the drug
in the small intestine. 75
Ocular Delivery :
Effective tear drainage; blinking &Low permeability
of the cornea.
Limited absorption due to rapid elimination leading
to poor ophthalmic bioavailability.
Due to the short retention time, a frequent dosing
regimen is necessary for required therapeutic
efficacy.
Drawbacks with ocular route
76
Ocular Delivery :
Silicone rubber Hydrogel composite ophthalmic
inserts extended the duration of the Pilocarpine to
10 hr, compared to 3 hr when Pilocarpine nitrate was
dosed as a solution.
Hydrogels in Ocular Delivery
77
Ocular Delivery :
In-situ forming Hydrogels are attractive as an ocular
drug delivery system because of their facility in
dosing as a liquid,and long term retention property as
a gel after dosing.
Hydrogels in Ocular Delivery
78
Ocular Delivery :
Swollen Hydrogels can deliver drugs for long duration.
Easy to remove.
Patient compliance is high.
Advantages
79
Transdermal Delivery :
Drug delivery to the skin has been generally used to treat skin diseases or for disinfections
of the skin.
Transdermal route is employed for systemic
delivery of drugs.
Purpose
80
Transdermal Delivery :
The possible benefits of transdermal drug delivery
are - drugs can be delivered for a long duration.
- drugs can be delivered at a constant rate.
- drug delivery can be easily interrupted on
demand by simply removing the devices.
- drugs can bypass hepatic first-pass
metabolism.81
Transdermal Delivery :
Furthermore, because of their high water content,
swollen hydrogels can provide a better feeling for
the skin in comparison to conventional ointments
and patches.
82
Subcutaneous delivery:
Subcutaneously inserted exogenous materials may
more or less evoke potentially undesirable body
responses, such as inflammation, carcinogenecity
and immunogenecity.
Therefore, biocompatibility is a prerequisite that
makes materials implantable.
83
Subcutaneous delivery:
Due to their high water content, hydrogels are
generally considered as biocompatible materials.
They also provide several promising properties:
* minimal mechanical irritation upon in-vivo
implantation, due to their soft, elastic properties.
84
Subcutaneous delivery:
* Prevention of protein adsorption and cell
adhesion arising from the low interfacial
tension between water and hydrogels;
* Broad acceptability for individual drugs with
different hydrophilicities and molecular sizes
* Unique possibilities to manipulate the release of incorporated drugs by crosslinking density
and swelling. 85
Hydrogels To Fix Bone Replacements:
Provided orthopedic fasteners and replacements hip and knee replacements, etc. are coated with
Hydrogels which expand in the presence of liquids.
Swelling of such coatings causes the fastener or
replacement to be securely fixed into position once
inserted into bone material.
86
Hydrogels To Fix Bone Replacements:
87
Protein Drug Delivery:
Interleukins are conventionally given as injection.
Hydrogels have the following advantages
-Better patient compliance.
-Hydrogels form insitu and release proteins
slowly
-They are biodegradable and biocompatible.
Hydrogels have the following advantages
-Better patient compliance.
-Hydrogels form insitu and release proteins
slowly
-They are biodegradable and biocompatible.88
Topical Drug Delivery:
Hydrogels are used to deliver drugs like Desonide
(synthetic corticosteroid) usually used as an anti-
inflammatory.
Hydrogels with their moisturizing properties avoids
scaling and dryness and has better patient
compliance.
89
Topical Drug Delivery:
Antifungal formulations like Cotrimazole has been
developed as Hydrogel formulation for vaginitis and
shows better absorption than conventional cream
formulations.
90
Tissue Engineering:
Microgels (micronized Hydrogels) can be used to
deliver macromolecules like phagosomes in to
cytoplasm of antigen-presenting cells.
The release is because of acidic conditions. Hydrogels
mold themselves to the pattern of membranes of the
tissues and have sufficient mechanical strength.
This property is also used in cartilage repairing
91
In The Treatment Lower Extremity Diabetic ulcers:
Diabetic ulcers are the primary cause of amputations
of the leg, foot,or toe.
NanoDOX™
A topical doxycycline Hydrogel for chronic wounds
NanoDOX™ contains 1% Doxycycline Monohydrate
Hydrogel.
Improve the topical delivery to increase local efficacy
92
Rectal Delivery:
This route has been used to deliver many types of
drugs for treatment of diseases associated with the
rectum, such as hemorrhoids.
ADVANTAGES:
This route is an ideal way to administer drugs
suffering heavy first-pass metabolism.
93
Rectal Delivery:
DRAWBACKS:
Patients compliance is less due to discomfort
arising from given dosage forms.
Substantial variability in patient’s acceptance of
treatment. this leads to variation of availability of
drugs.
94
Summary & Conclusion:
Recent developments in the field of polymer
science and technology has led to the development
of various stimuli sensitive hydrogels like pH,
temperature sensitive, which are used for the targeted
delivery of proteins to colon, and chemotherapeutic
agents to tumors.
95
Summary & Conclusion:
Some environmental variables, such as low pH and
elevated temperatures, are found in the body.
For this reason, either pH-sensitive and/or
temperature sensitive hydrogels can be used for
site-specific controlled drug delivery.
96
Summary & Conclusion:
Hydrogels that are responsive to specific molecules,
such as glucose or antigens, can be used as biosensors as well as drug delivery systems.
The hydrogels may be suitable as a wound
substitutes and can be used in wound healing.
97
Summary & Conclusion:
New synthetic methods have been used to prepare
homo- and co-polymeric hydrogels for a wide
range of drugs, peptides, and protein delivery
applications.
Hydrogels are also used in regenerating
human tissue cells.
98
References:
1.Remington: The Science and Practice of Pharmacy.
Published by Lippincott Williams & Wilkins, 2005.
Twenty-First Editions. P.NO. 294,756,867,868.
2. Handbook of Pharmaceutical Excipients, A. Wade and P.J.
Weller ed., The Pharmaceutical Press, London, 1994, pp.
229–232.
3. British Pharmacopoeia 2002, the Stationary Office,
London, 2002, p. 2092–2094.
99
Thank You
100