Transcript Psy-cl-poly(AAm-co-MAAm) hydrogels

NIRMALA CHAUHAN
DEPARTMENT OF CHEMISTRY
GOVT. COLLEGE KULLU
(HIMACHAL PRADESH UNIVERSITY)
SHIMLA (INDIA)
Diabetes mellitus is a common problem nowadays
• Caused by decreased production of insulin
• Or by decreased ability to use insulin
• Which leads to an increase in blood glucose level
Due to the inconvenience of the traditional treatment of
diabetes by subcutaneous administration of insulin injection,
various attempts have been made to develop an efficient
method of insulin delivery.
Classical drug delivery
In conventional drug delivery systems:
• Insulin is injected subcutaneously 2 to 4 times in a day
• To achieve a near physiological pattern of insulin
secretion
Problems associated with this approach
•
•
•
•
Reduced potencies because of partial degradation
Toxic levels of administration
Increase costs associated with excess dosing
Compliance issue due to administration pain
Therefore, there has been significant interest in the
development of oral delivery systems for insulin
• That could release the drug in a constant level for longer
periods
• Patients would be freed from the need to administer multiple
doses
Controlled drug delivery system
A system by which drugs are made available to a site of
action in specific concentration for desired period.
Why control drug delivery?
To maintain an ideal pharmacokinetic profile
Goals:
• Deploy to a target site to limit
•
•
•
•
side effects
Shepard drugs through specific
areas of the body without
degradation
Maintain a therapeutic drug
level for prolonged periods of
time
Predictable controllable release
rates
Reduce dosing frequent and
increase patient compliance
Plot of drug concentration versus time for different release methods
In an ideal case scenario, such a profile can be achieved by use of the polymer
matrix as drug releasing device which :
• Releases the drug in controlled and sustained manner to maintain the
therapeutic level
In addition, the polymeric materials provide the most important
avenues for research:
• Primarily because of their ease of processing
• Ability of researchers to control their physical and chemical
properties
Among these :
• Hydrogels, specially based on the polysaccharides:
 Attracted considerable attention
 Act as a smart candidate
 For the control release of therapeutic agents
 To specific sites in the GI tract
Hydrogels
• Hydrogels are cross-linked, hydrophilic, 3-D polymer networks
• Swell quickly by imbibing a large amount of water (> 20% of their dry
•
•
•
•
mass)
or de-swell in response to changes in their external environment.
The volume phase transitions as a response to different stimuli
Make these materials interesting objects of scientific observations
Useful materials for use in drug delivery systems.
mer
mer
mer
mer
mer
mer
mer
mer
Add water
mer
mer
mer
mer
mer
mer
mer
mer
Preparation of hydrogels
1.Bulk Polymerization 2. Solution Polymerization 3. Suspension Polymerization
Schematic methods for formation of crosslinked polymers
M1
M1
M1
M1
M1
M1
M1
(H o m o p o ly m e r )
M1
M1
M2
M1
M2
M1
M2
M1
M2
M1
M1
M2
M2
(Monomer)
M1
M1
M2
M2
(Graft copolymer)
M2
(Block copolymer)
(Polymer backbone)
M1
M1
M2
(Alternate copolymer)
(Random copolym er)
M1
M2
(Crosslinked polymer)
Where M1 and M2 are the two different monomers
Figure 5. The homopolymers, copolymers and IPNs.
M2
M2
The goal of oral insulin delivery devices is to design:
• pH responsive hydrogels
• To protect the sensitive drug from
• Proteolytic degradation in the acidic environment
(stomach) and
• Upper portion of the small intestine before releasing in the
small intestine
Polysaccharide based hydrogels
Polysaccharide-based formulations are non-toxic, safe,
biocompatible, biodegradable, abundant and colon specific.
Polysaccharide based hydrogels:
 Enhance the intestinal absorption of insulin
 Increase the relative pharmacological bioavailability of insulin
Psyllium is medicinally important natural polysaccharide and
hydrogels developed from it will have all the properties.
Psyllium
Derived from the dried, ripe seeds of Plantago psyllium
A white fibrous hydrophilic material which forms the
colorless mucilaginous gel by absorbing water.
Chemically, it is composed of hemicellulose which consists of
xylan backbone linked with arabinose, rhamnose and
galacturonic acids units collectively known as arabinoxylans.
Arabinoxylans have β-1,4-linked D-xylopyranose units joined in
linear fashion and side branches of α-L-arabinofuranose residues.
Furanose conformations of side branches are the sites of water
absorption due to their flexible nature.
• Main structural features of the mucilage from Plantago
ovata Forsk.
Scheme 2. Structural representation of Psyllium( Plantago ovata )
H
H
O
H
O
HO
H
H
H
O
H
-L-Rhamnopyranose
OH
H
H
H
H
O
-L-Arbinofuranose
O
H
H
H
H
(1-3)
(1-3)
H
-D-Xylopyranose
H
OH
H
OH
OH
-D-Xylopyranose
H
H O
H
(1-4) O
H
O
H
H
H
Psyllium region (B)
O
HO
H
O
H
(1-3)
O
(1-2) O
OH
(1-4)
O
(1-3)
O
OH
O
OH
-L-Arabinofuranose
H
O
H
H
H
H
O
H
OH
H H
OH
H
H
HO
H
H
H O
H
OH
O
H
-D-Xylopyranose
OH
H
H
H
(1-4)
O
H
H
H
OH
O
H
OH
H
-L-Rahmanopyranose
H
O
H
H
OH
HOOC
HO
H
-D-Galactouronicacid
H
H
OH
H
OH
H
OH
-D-Xylopyranose
-D-Xylopyranose
-L-Arabinofuranose
H
O
H
OH
OH
OH
H
H
O
O (1-2)
H
H
O
(1-4)
H
OH
O (1-3) O
(1-2)
H
H
(1-3)
O
OH
H
(1-3)
O
H3C
HO
H
HO
H
OH
O H
(1-4)
H O
H
H
H
H
H
O
(1-3)
HO
H
OH
O
H
H
H
H
-L-Arabinofuranose
HO
OH
OH
O (1-4)
H
H
HO
H
H
H
H
H
H
OH
H
H
-D-Xylopyranose
O
O
OH
O (1-3)
O
H
H
O
OH
H
H
(1-4)
OH
H
OH
H
OH
-D-Galactouronicacid
H
H O
H
(1-4)
H
H O
O
OH
HOOC
HO
H
O
OH
H O
H
OH
H
H
H
H
O
H
O
HO
OH
H
H
H
(1-3) O
OH
HO
H
(1-2)
H
CH3
OH
H
H
O
O
(1-3)
OH
H
O (1-3)
O
H
(1-4)
O
H
H
H
H
H
H O
Psyllium region (A)
H
HO
H
Constipation
Cholesterol
lowering
Diabetes
Diarrhea
Psyllium as
therapeutic
agent
Colon
cancer
Ulcerative
colitis
Irritable
bowel
syndrome
Psyllium and Diabetes
Psyllium has been proposed as a possible treatment for high
blood sugar level and viscous form of psyllium have shown
improved blood control by:
•
•
•
•
•
Trapping the ingested carbohydrates inside the viscous gel formed after
digestion
As a result sugar are absorbed into the blood stream more slowly
It increases the viscosity of intestinal contents
Therefore decrease the rate of absorption of glucose, bile acids and
other nutrients
Decreases postprandial glucose concentrations
Mechanism of action of gel forming fiber is related to:
• Ability to increase the viscosity of the gastrointestinal contents
• Thus, interfere with motility and absorption
• Improves glucose tolerance in diabetes, due to
• Retarded gastric emptying and increased intestinal transit
Schematic
representation
of
stomach and small intestine
showing:
(A)slow digestion and absorption of
'fibre rich‘ diet and
(B) rapid digestion and absorption of
energy-dense food from low fibre
diets
Insulin as a model drug
Insulin is a hormone that :
•
•
•
•
Regulates the amount of glucose (sugar) in the blood
Required for the body to function normally
Without insulin, the blood glucose builds up in blood
Cells are starved of their energy source.
Keeping in view, the pharmacological importance of
psyllium polysaccharides to reduce glucose absorption
and drug delivery devices based on hydrogels, psyllium,
if suitably tailored to prepare the hydrogels, can act as
the double potential candidates to develop novel drug
delivery systems.
Modification of natural polymers is important to improve their chemical and
physical properties.
The main objectives of the present study
To use psyllium, a medicinally important polysaccharide:





For developing the novel pH responsive hydrogels for the use in insulin
delivery
To synthesize psyllium and vinylic monomers (acrylamide,
methacrylamide) based hydrogels by chemical induced crosslinked
polymerization
To characterize these polymers/hydrogels by different physical
techniques such as SEMs, FTIR and TGA for evaluation of structural
aspects.
To study the swelling kinetics of the hydrogels as a function of , pH, for
the evaluation of swelling mechanism and diffusion coefficients for the
swelling of the hydrogels.
To study the in vitro release dynamics of model drug insulin, from the
drug loaded hydrogels in different release medium, for the evaluation of
the release mechanism and diffusion coefficients.
Materials and Method
•
•
•
•
•
Plantago psyllium (Sidpur Sat Isabgol factory, India)
Acrylamide, Methacrylamide (Merck Schuchardt, Hohenbrunn, Germany)
Sodium potassium tartrate and Folin’s reagent(Merck-Mumbai-India)
Ammonium persulphate, Copper sulphate and N-N’-methylenebisacrylamide
(S.D Fine, Mumbai-India)
Insulin (Torrent Pharmaceuticals-Mehsana, Gujrat-India)
MONOMER
(CH2=CXY)
Acrylamide( AAm)
Methacrylamide(MAAm)
X
o
C
NH2
o
C
NH2
Y
POLYMER
-(CH2-CXY-)n
H
Poly(AAm)
CH3
Poly(MAAm)
Synthesis of Hydrogels
Graft copolymerization method
By free radical polymerization.
STEP-1
Psyllium
STEP-2
Monomer
(AAm/MAAm)
Crosslinker
(NN’-MBA)
Water
Initiator
(APS)
Stirred
Homogenous
Solution-1
Add in solution 1
Synthesis
Homogenous
Solution-2
Kept at 65°C temperature for 2h
in a reaction system.
Hydrogels thus formed
Stirred
2h with distilled water and
2h with ethanol and then
dried in oven at 40°C
Psy-cl-poly(AAm) hydrogels
Psy-cl-poly(AAm-co-MAAm) hydrogel
Release dynamics of Insulin from drug loaded hydrogels
Preparation of
calibration curves
Drug loading to
polymer matrix
Drug release
from
polymer matrix
Distilled water
λmax 768nm
Insulin
Swelling equilibrium
method at 37ºC
for 24hrs
pH 2.2 buffer
λmax 753 nm
pH 7.4 buffer
λmax 758nm
Mechanism of swelling and drug release
Based on the relative rate of
diffusion of water into polymer
matrix and rate of polymer chain
relaxation, swelling and the drug
release profiles classified into
three
types
of
diffusion
mechanisms:
•
Normal
Fickian
diffusion
is
characterized by n < 0.5,
• Case II diffusion by n > 1.0.
• Non-Fickian or anomalous diffusion
indicates value of n between 0.5 and
1.0
On the basis of power law expression given
by Ritger and Peppas shown in figure :
M S  kt n
Mt
 kt n
M
Mt
 Di t 
 4
2 
M
 π 
DA
0.5
0.049 2

t1/2
 (π 2 DL t) 
Mt
 8 
 1   2 exp 

M
2
π 


Mechanism for the swelling and release
dynamics of drug from hydrogels
Case I or
Simple Fickian
diffusion
It occurs when the
rate of diffusion is
much less than that
of relaxation
Case II diffusion
It
occurs
when
diffusion is very
rapid compared with
the
relaxation
process
Non-Fickian or
Anomalous
diffusion
It occurs when the
relaxation
and
diffusion rates are
comparable
Mechanism of Polymerization
Inititaion
S2O82Initiator
.
SO4+
Psy
OH
.
2SO4-
CR
CH2
.
OH
H2O
.
OH
+
Psyllium
HSO4-
+
.
O
Psy
.
OH
+
(i)
HO
+
(ii)
H2O
(iii)
.
CR
(iv)
CH2
CONH2
Vinyl monomer
CONH2
Where, R= H in case of Acrylamide
R= -CH3 in case of Methacrylamide
HO
.
CR
CH2
O2
R
C
CH2
HO
CONH2
.
Psy O
+
CH2
.
CR
+
CH2
HO [ CH2
CONH2
n CH2
CR
PsyO
CH2
CONH2
CONH2
.
CR
CONH2
(vi)
.
CR
CH2
n
CONH2
CONH2
Homopolymer Macroradical
CR
n CH2
CONH2
PsyO
PsyO
CH2
Propagation
.
CR
HO
CH2
(v)
CONH2
CR
CONH2
Vinyl monomer
+
.
O
O
CR [ CH2
CONH2
Vinyl monomer
(vii)
CR ]
CR] CH2
n-2
CONH2
CR
CH2
CONH2
.
(viii)
CR
CONH2
Psy-g-(M) Macroradical I
HO
CH2
CR
O
.
O
CONH2
PsyO
CH2
CR
[CH2
CONH2
CR]
CH2
n-2
CONH2
.
C
CH2
CONH2
Psy-g-(M) Macroradical II
.
CR
+
CONH2
HO
CH2
CR
O
CONH2
OR
(ix)
PsyO
CR [ CH2
CH2
CONH2
.
C
CH2
CH2
n-2
CONH2
CONH2
CR]
.
CR +
O
N
H
N
H
CONH2
.
CH2
O
CH
O
HN
(NN-MBA)
Psy-g-(M) Macroradical II
(x)
HN
O
CH
CH2
PsyO
.
[ CH2 CR] CH2 C CH2 CR
n-2
CONH2
CONH
CONH2
2
CONH
CH2 CR
2
Psy-cl-(M) macroradical III
Termination
.
CH2
CH
O
HN
HN
O
. CR H2C
CONH2
CONH2
CH2 ] CR
n-2
CH2 OPsy
CH2
+
CH
HN
CH2
.
C CH2 CR
HN
Psy-cl-(M) macroradical III
CONH2
CH2 [ CR
C
CH
[CH2 CR] CH2
n-2
CONH2
CONH2 CONH2 CONH2
PsyO CH2 CR
CONH2
O
O
CH
.CH2
Psy-cl-(M) macroradical III
CONH2
CONH2
CR H2C
C
CH2
[ CR
]n-2CR
CH2
CH2
CH
O
O
HN
HN
HN
O
O
CH
CH
CH2
PsyO
CH2 CR
[ CH
2
]
OPsy
CH2
CH
HN
CH2
CONH2
CONH2
CR CH2 C CH2
n-2
CR
CH2
CONH2 CONH2 CONH2
CONH2
Psyllium crosslinked poly(M) networks or [Psy-cl-poly (M)] hydrogels
Where, Psy-OH = Psyllium g = Grafting cl = Crosslinking
(xi)
Characterization
All psyllium crosslinked hydrogels synthesized at optimum
reaction parameters were characterized by using:
• Scanning electron micrography (SEM)
• Energy dispersion X-ray analysis (EDAX)
• Fourier transform infrared spectroscopy (FTIR)
• Thermogravimetric analysis (TGA)
• Swelling studies
SEMS Analysis
To investigate the surface morphology of crosslinked hydrogels prepared by
chemical method SEM’s were taken at different magnification reveals that
•
•
Psyllium has homogeneous surface
Crosslinked polymer show a structure heterogeneity-porous structure-regions for water
permeation and interaction sites of external stimuli with hydrophilic group of polymers
Psyllium
Psy-cl-poly(AAm) hydrogels
Psy-cl-poly(Aam-co-MAAm) hydrogels
EDAX Analysis
To investigate the elemental composition of psyllium and crosslinked
polymeric hydrogels EDAX were taken
Table: Results of EDAX for elemental composition (Wt %) of psyllium and
crosslinked hydrogels prepared by chemical method.
Polymers
Psyllium
Psy-cl-poly(AAm) hydrogels
Psy-cl-poly(AAm-co-MAAm)
hydrogels
C
O
N
45.66
47.79
-
45.52
42.44
12.03
47.22
44.13
8.65
Na
Ca
K
Cl
-
-
-
-
-
-
-
-
FTIR Spectra
FTIR spectra of psyllium, psy-cl-poly(AAm) polymers were recorded in KBr pellets on Nicolet 5700 FTIR (THERMO).
100 **psy
469.5
749.3
898.3
1269.4
1161.3
1078.3
1458.2
1398.2
1637.7
1560.3
1728.0
75
2926.3
80
3425.6
85
3909.4
3805.3 3863.4
3754.4
The absorption bands at:
3425.6 cm-1 = hydroxyl groups, 1200-1030 cm-1
due to C–O
and C–O–C
stretching
characteristic
peaks
of
natural
polysaccharides, band at 930-820 cm-1 and
785-730 cm-1 vibrational mode of pyranose
ring of polysaccharides.
%Transmittance
90
2121.1
95
70
Psyllium
65
60
4000
3000
2000
1000
W aven umb ers (cm-1)
100 **psyaam
897.7
95
90
80
474.5
2145.7
85
70
1042.3
1457.5
75
60
55
1664.3
2926.1
65
3421.6
%Transmittance
Besides the absorption peaks on psyllium, ,
the bands at 1664.3 cm-1 , 1611cm-1 and
1353.4cm-1
due
to
C=O
stretching(Amide-I),
N-H
in-plane
bending(Amide-II) and C-N stretching
vibrations(Amide-III) respectively.
50
4000
3000
2000
W aven umb ers (cm-1)
Psy-cl-poly(AAm) polymer
1000
TGA Analysis
Psyllium
DTG TGA
(g/min) (%)
The primary thermograms (TGA, DTA
and DTG) of psyllium and crosslinked
polymers
were
taken.
These
thermograms were obtained in the
range 20-800oC under air atmosphere at
10oC/min heating rate.
DTA
(V)
200
TGA
DTG
DTA
100
8000
150
80
6000
60
100
40
50
4000
2000
20
0
0
0
-50
0
100
200
300
400
500
600
o
DTA
(V)
DTG TGA
(g/min) (%)
400
20
TGA
DTG
DTA
100
Temperature ( C)
DTA
(V)
DTG TGA
(g/min) (%)
500
100
400
80
40
TGA
DTG
DTA
35
30
80
25
300
10
300
60
20
60
15
200
40
200
40
100
20
0
0
10
5
0
100
0
20
-5
-10
0
0
0
100
200
300
400
500
o
Temperature ( C)
Psy-cl-poly(AAm)hydrogel
600
700
-10
800
0
100
200
300
400
500
600
700
o
Temperature ( C)
Psy-cl-poly(AAm-co-MAAm) hydrogels
800
Thermo Gravimetric Analysis
Table: Thermo gravimetric analysis of Psyllium and crosslinked hydrogels prepared by chemical
method.
Sample
Psyllium
Psy-cl-poly(AAm)
Psy-cl-poly(AAm-coMAAm) hydrogels
IDT
(oC)
FDT
(oC)
220
DT(0C) at every 10% weight loss
10
20
30
40
50
60
70
80
90
100
Residue
left (%)
548
192
278
294
298
301
306
369
424
460
548
1.80
216
622
90
238
269
325
377
451
503
542
581
622
0.97
225
607
115
246
272
313
370
438
499
538
573
607
0.54
Since the pH change occurs at many specific or physiological sites
in the body, it is one of the important parameters in the
design of drug delivery systems. Utilization of pH changes
within the GI tract is of special interest for the controlled drug
delivery.
To understand the effect of pH on water uptake by the hydrogels, the
most common approach used is the study of gel swelling.
• Swelling studies were carried out in distilled water, pH 2.2 buffer
and pH 7.4 buffer for 24 h at 37 oC.
Swelling as a function of pH
Swelling has been observed maximum in pH7.4 buffer as compared to pH2.2 buffer
because in basic medium–COO- groups ionize and charged carboxylate groups repel each
other and expand the polymer networks. Non-Fickian diffusion has been observed
8
Distilled water
pH 2.2 buffer
pH 7.4 buffer
Distilled water
pH 2.2 buffer
pH 7.4 buffer
12
Amount of water uptake (g/g of gel)
Amount of water uptake (g/g of gel)
7
6
5
4
3
2
1
10
8
6
4
2
0
0
30
60
90
120
150
180
210
240
270
300
1440
Time (min.)
Swelling kinetics of psy-cl-poly(AAm) hydrogels in different medium
o
at 37 C
30
60
90
120
150
180
210
240
270
300
1440
Time (min.)
Swelling kinetics of psy-cl-poly(AAm-co-MAAm) hydrogels in different
o
medium at 37 C.
Table : Results of diffusion exponent ‘n’, gel characteristic constant ‘k’ and various
diffusion coefficients for the swelling kinetics of psy-cl-poly(AAm) and psy-cl-poly(Aamco-MAAm) hydrogels in distilled water at 37 oC.
Drug in
releasing
medium
Diffusion
exponent ‘n’
Gel
characteristic
constant
‘k’×102
Initial
Di×104
Diffusion coefficients
(cm2/min)
Average
DA×104
Late Time
DL×104
Psy-cl-poly(AAm) based hydrogels
Distilled Water
pH 2.2 buffer
pH 7.4 buffer
0.66
1.15
4.74
7.41
0.69
0.54
2.75
8.51
12.83
1.35
0.61
1.52
6.59
10.89
1.01
Psy-cl-poly(AAm-co-MAAm) based hydrogels
Distilled Water
pH 2.2 buffer
pH 7.4 buffer
0.69
0.74
1.74
3.87
0.32
0.70
0.68
2.36
5.16
0.38
0.65
0.94
1.72
4.07
0.31
In designing a device for oral delivery of sensitive peptide drug such
as insulin, it is important to protect the drug in the harsh
environment of the stomach and upper GI tract and release the
drug into the distal portions of the intestine. Therefore, in an
effective carrier the release rates must be significantly greater in
neutral or basic conditions than acidic conditions.
In vitro release dynamics of Insulin from
Psyllium crosslinked hydrogels
The release of water soluble drug entrapped in a hydrogels
occurs :
• Water penetrates into the network
• Swell the polymer and dissolve the drug
• Followed by diffusion along the aqueous pathways to the surface
of the device
The release of the drug is closely related to :
• Swelling characteristics of the hydrogels which in turn
• Key function of chemical architecture of the hydrogels
Release profile of Insulin
The release of insulin has been observed more in pH7.4 buffer as compared to
pH 2.2 buffer. This observation may be explained on the basis of swelling of the
hydrogels which has also been observed higher in pH 7.4 buffer.
Distilled water
pH 2.2 buffer
pH 7.4 buffer
30
Amount of drug release
after 24hrs (ug/10mL /g of the gel)
Amount of drug released (µg/g of gel)
35
25
20
15
10
5
0
30
60
90
120
150
180
210
240
270
300
1440
30
A=Distilled water
B= pH 2.2 buffer
C= pH 7.4 buffer
20
10
0
Time (min.)
A
Release profile of insulin from drug loaded psy-cl-poly(AAm) hydrogels
o
in different medium at 37 C.
60
C
70
Distilled water
pH 2.2 buffer
pH 7.4 buffer
Amount of drug release
after 24hrs (ug/10mL /g of the gel)
Amount of drug released (µg/g of gel)
B
Different release medium
50
40
30
20
60
A=Distilled water
B= pH 2.2 buffer
C= pH 7.4 buffer
50
40
30
20
10
10
0
30
60
90
120
150
180
210
240
270
300
1440
Time (min.)
Release profile of insulin from drug loaded psy-cl-poly(AAm-co-MAAm)
o
hydrogels in different medium at 37 C.
A
B
Different release medium
C
• The release of insulin in pH7.4 and pH2.2 buffer occurred through a
non-Fickian and Fickian diffusion mechanisms.
• The values of initial and average diffusion coefficients (i.e. earlier
stages diffusion coefficients) have been observed higher than the
late diffusion coefficients.
• This may be due to the higher concentration gradient of the insulin
in the earlier stages of diffusion than late stages of diffusion.
It means after maintaining the certain concentration, the release of
drug from the polymer matrix occurred slowly and this is very
important observation for designing the controlled drug delivery
systems.
Table : Results of diffusion exponent ‘n’, gel characteristic constant ‘k’ and various
diffusion coefficients for the release of model drug (Insulin) from drug loaded hydrogels
in different medium at 37oC.
Drug in
releasing
medium
Diffusion
exponent ‘n’
Gel
characteristic
constant
‘k’×102
Initial
Di×104
Diffusion coefficients
(cm2/min)
Average
DA×104
Late Time
DL×104
Psy-cl-poly(AAm) based hydrogels
Distilled Water
pH 2.2 buffer
pH 7.4 buffer
0.81
0.87
18.0
16.95
2.25
0.38
8.39
7.47
19.88
1.60
0.60
2.73
19.69
20.44
3.19
Psy-cl-poly(AAm-co-MAAm) based hydrogels
Distilled Water
pH 2.2 buffer
pH 7.4 buffer
0.60
3.29
8.33
7.61
1.69
0.40
10.69
5.82
12.75
2.01
0.57
3.46
7.83
7.96
1.34
Conclusion
From the foregone discussion it can be concluded that :
• Drug delivery system developed from the modification of the
psyllium have the double potential
Here double potential of these delivery systems is due to :
• Therapeutic importance of psyllium to cure the diabetes and
• Release of curative agents from drug loaded hydrogels on the
other hand
• This will release the insulin in the colon in a controlled and
sustained manner,
• Polymer degradation in the colon will release the psyllium,
which itself has been proposed as a glucose lowering agent
• Degradation of the polymer matrix and release of drug may
exert the synergic effect
It is further it can be concluded that the swelling of the
Crosslinked hydrogels:
• Higher in pH 7.4 buffer as compared to pH 2.2 buffer
• Hydrogels have been found pH responsive
Thus could be exploited for developing the site specific drug
delivery systems.
Further reading:
B. Singh, N. Chauhan / International Journal of Diabetes Mellitus 2 (2010) 32–37
B. Singh, N. Chauhan / Food Hydrocolloids 23 (2009) 928–935
Thank You