174 - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/8262/15/15... · 2015-12-04 · 174 8....

174

8. Formulation and evaluation of mucoadhesive hydrogels of

Famotidine

The mucoadhesive hydrogels of Famotidine were prepared by

physical cross linking ionotropic gelation method, which is the method

most widely, used by a good number of researchers for the

preparation of alginate beads and hydrogels.

8.1 Construction of calibration curve

An accurately weighed 100 mg of Famotidine was dissolved in

pH 1.2 Hcl as per I.P178 and make up the volume up to 100 ml in a

volumetric flask, (Stock Solution: I, 1000 µg/ml). From this 10 ml of

solution was pipetted out and make up the volume up to 100 ml

(Stock Solution: II, 50 µg/ml). Then the aliquots were prepared, whose

concentration ranging from 2 to 20 µg/ml and the absorbance were

measured at 265 nm by using by using UV spectrophotometer,

Schimadzu-1200, against the reagent blank.

Table 8.1: Calibration curve data of Famotidine at pH 1.2

Concentration in µg/ml Absorbance at 265 nm0 02 0.0744 0.1476 0.2068 0.26810 0.34512 0.41814 0.48816 0.55118 0.62720 0.742

175

Fig: 8.1. Calibration curve of Famotidine

8.2 Formulation of mucoadhesive hydrogels

8.2.1 Formulation of placebo hydrogel beads

The Hydrogels were prepared by the method of physical

crosslinking (orifice ionotropic gelation technique). An accurately

weighed quantity of sodium alginate, HPMC - K100, SCMC and

carbopol were dissolved in required quantity of distilled water and this

solution is being homogenised at 500 rpm for 30 min. This solution

was sonicated for 30 min to remove air bubbles thus the solution was

dropped into 2 % cacl2 solution (crosslinking agent) using 21G syringe

and the formed hydrogels were cured for 30 min. These hydrogels

176

were washed with distilled water and dried at room temperature for 12

hours179.

8.2.2 Formulation of drug encapsulated hydrogel beads

Beads containing Famotidine were prepared by employing

sodium alginate in combination with HPMC-K100, SCMC, and

carbopol. An orifice ionic gelation process was used to prepare large

sized alginate beads. Sodium alginate and polymers were dissolved in

distilled water to form a homogeneous polymer solution; Famotidine

was added to the polymer solution and mixed thoroughly to form a

smooth viscous dispersion made upto 100 ml. The resulting

dispersion was then injected as a thin stream in to a 2 % w/v calcium

chloride solution was then added slowly while stirring for ionic

gelation reaction. Stirring was continued for 15 min to complete the

curing reaction and to produce spherical beads. Mixture was then

centrifuged and the product thus separated was washed repeatedly

with water and dried at room temperature for 12 hours. The prepared

beads were stored in a dessicator for further studies.

177

Table 8.2: Composition of mucoadhesive hydrogels of Famotidine

Formulation

Code

Drug

in g

Polymers in g

Sodium

alginateHPMC -K100

SCMC Carbopol

H1 0.5 1.0 2.0 - -

H2 0.5 1.0 - 2.0 -

H3 0.5 1.0 - - 2.0

H4 0.5 1.0 1.0 1.0 -

H5 0.5 1.0 1.0 - 1.0

H6 0.5 1.0 - 1.0 1.0

H7 0.5 1.0 1.0 0.5 0.5

H8 0.5 1.0 0.5 0.5 1.0

H9 0.5 1.0 0.5 1.0 0.5

H10 0.5 1.0 1.5 0.5 -

H11 0.5 1.0 - 1.5 0.5

H12 0.5 1.0 0.5 - 1.5

H13 0.5 1.0 1.5 - 0.5

H14 0.5 1.0 0.5 1.5 -

H15 0.5 1.0 - 0.5 1.5

2% W/V solution of calcium chloride is used as crosslinking agent.

178

Fig: 8.2 (a & b). Formulation H1 before and after drying



179

8.3 Evaluation of Famotidine hydrogels

8.3.1 Evaluation of micromeritic properties

Angle of repose

Angle of repose has been used as an indirect method of

quantifying powder flow ability, because of their relationship with

interparticle cohesion. A static heap of powder will begin to slide when

the angle of inclination is large enough to overcome frictional forces.

This sliding will stop when the angle of inclination is below to that of

the required to overcome adhesion/cohesion, i.e. sliding occurs until

the gravitational forces balance the inter-particle forces. This balance

of forces causes the powder poured from a container onto a horizontal

surface to form conical mount or heap. The sides of the heap formed

in this way make an angle with the horizontal which is called the

angle of repose represented by θ.

Where θ = Angle of repose

h = height of heap

r =horizontal surface radius of heap.

Bulk density

An accurately weighed quantity of hydrogel beads were poured

into graduated cylinder. Then the volume was measured directly from

the graduation marks on the cylinder as ml. The volume measure was

called as the bulk volume and the bulk density is calculated by

following formula

180

Tapped density

Tapped density refers to the bulk density of the powder after a

specified compaction process, usually involving vibration of the

container. After measuring the bulk volume the same measuring

cylinder was set into tap density apparatus. The tapped density is

calculated by the following formula.

Carr’s Index

It is one of the most important parameter to characteristic the

nature of powders and granules. It can be calculated from the

following equation.

Hausner’s ratio

Hausner’s ratio is an important character to determine the flow

property of powder and granules. This can be calculation by the

following formula

181

Table 8.3: Micrometric properties of formulations H1 – H15

Formulationcode

Angle ofrepose(θ) ± SD

Bulkdensity(g/cc) ±SD

Tappeddensity(g/cc) ±SD

Carr’sindex(%) ± SD

Hausner’sratio± SD

H1 28.15 ±0.015

0.797 ±0.010

0.904 ±0.026

11.83 ±0.115

1.131 ±0.015

H2 30.65 ±0.017

0.811 ±0.005

0.862 ±0.005

05.91 ±0.152

1.062 ±0.010

H3 20.72 ±0.011

0.524 ±0.011

0.561 ±0.011

06.65 ±0.057

1.070 ±0.005

H4 30.04 ±0.022

0.728 ±0.015

0.827 ±0.010

11.97 ±0.115

1.135 ±0.011

H5 20.15 ±0.015

0.832 ±0.015

0.896 ±0.010

07.14 ±0.111

1.076 ±0.005

H6 21.49 ±0.005

0.787 ±0.015

0.840 ±0.011

06.30 ±0.010

1.067 ±0.005

H7 27.73 ±0.011

0.717 ±0.005

0.743 ±0.005

03.59 ±0.010

1.036 ±0.011

H8 26.96 ±0.026

0.840 ±0.011

0.896 ±0.026

06.25 ±0.012

1.066 ±0.026

H9 26.53 ±0.05

0.678 ±0.026

0.710 ±0.015

05.21 ±0.005

1.047 ±0.023

H10 27.82 ±0.015

0.698 ±0.018

0.745 ±0.005

06.30 ±0.015

1.067 ±0.016

H11 24.86 ±0.010

0.785 ±0.015

0.837 ±0.012

06.21 ±0.012

1.071 ±0.012

H12 27.93 ±0.011

0.446 ±0.012

0.464 ±0.011

04.27 ±0.015

1.040 ±0.005

H13 24.98 ±0.026

0.655 ±0.005

0.694 ±0.005

05.62 ±0.010

1.059 ±0.011

H14 28.75 ±0.011

0.854 ±0.010

0.920 ±0.015

07.17 ±0.026

1.077 ±0.012

H15 29.38 ±0.015

0.775 ±0.011

0.821 ±0.011

05.60 ±0.011

1.061 ±0.011

8.3.2 Evaluation of Equilibrium Swelling Ratio (ESR)

Swelling of hydrogels was carried out in triplicate by gravimetric

method. Known weight of hydrogels for were taken and immersed

excess of 1.2 Hcl buffer for different time intervals at 37ºc and then

hydrogels were removed, wiped with tissue paper to remove excess of

182

solvent and weighed immediately. The difference in weight has given

the amount of water up taken by hydrogels after definite time

intervals180.

Where, wt = weight of hydrogels at time.

wo = initial weight of hydrogels.

Table 8.4: Swelling ratio data for all formulations

Formulationcode

Time in h1 2 3 4 5 6

H1 1.2±0.05

2.6±0.1

4.5±0.1

5.4±0.15

7.2±0.05

7.6±0.05

H2 2.2±0.05

3.6±0.05

4.4±0.05

6.4±0.05

7.3±0.05

8.3±0.05

H3 2.7±0.11

4.3±0.05

6.2±0.11

7.5±0.1

10.7±0.05

11.2±0.05

H4 0.5±0.15

2.6±0.15

3.6±0.05

4.3±0.05

6.6±0.05

7.8±0.05

H5 1.3±0.1

3.4±0.15

4.7±0.05

5.4±0.05

7.3±0.11

9.3±0.11

H6 1.7±0.1

4.6±0.1

6.5±0.15

7.5±0.05

9.6±0.05

10.5±0.05

H7 1.0±0.1

2.6±0.1

5.3±0.11

9.4±0.05

9.6±0.05

10.6±0.05

H8 1.6±0.1

3.3±0.15

7.4±0.05

8.2±0.05

10.6±0.05

10.6±0.05

H9 2.5±0.05

4.8±0.15

6.9±0.05

8.9±0.05

9.6±0.05

10.6±0.05

H10 1.3±0.06

2.7±0.01

4.4±0.04

5.6±0.25

7.5±0.05

8.2±0.05

H11 2.3±0.05

3.4±0.05

5.1±0.05

7.2±0.05

7.8±0.05

8.5±0.05

H12 3.7±0.01

5.3±0.04

7.8±0.15

8.5±0.06

9.±0.07

10.9±0.08

H13 2.5±0.1

4.7±0.05

7.5±0.05

9.5±0.05

12.6±0.05

14.6±0.05

H14 2.3±0.11

4.4±0.15

6.7±0.05

8.4±0.05

9.3±0.11

10.3±0.11

H15 3.7±0.11

5.6±0.12

7.5±0.15

9.5±0.05

11.6±0.05

13.6±0.05

183

Fig: 8.5 Swelling ratio of Famotidine mucoadhesive hydrogels

8.3.3 Water uptake studies

Known weight of hydrogels for were taken and immersed in

excess of distilled water at 37ºc. Then the hydrogels were removed at

particular time intervals, wiped with tissue paper to remove excess of

solvent and weighed immediately. The difference in weight has given

the amount of water uptake by hydrogels for definite period of time181.

Where, WS = weight of swollen hydrogels.

WD = weight of dried hydrogels.

184

Table 8.5: Water uptake data for all formulations

Formulationcode

Time in h1 2 3 4 5 6

H1 68.72±0.16

81.06±0.15

85.18±0.05

89.30±0.02

93.41±0.11

97.53±0.15

H2 65.82±0.05

78.95±0.02

82.35±0.02

84.18±0.08

89.32±0.13

92.64±0.16

H3 63.83±0.02

75.32±0.01

79.65±0.15

82.14±0.15

87.64±0.13

90.85±0.03

H4 57.46±0.15

70.88±0.16

73.66±0.16

75.12±0.12

82.48±0.14

84.98±0.17

H5 55.48±0.16

68.46±0.05

71.64±0.14

73.19±0.12

80.68±0.08

83.36±0.03

H6 54.45±0.02

66.72±0.01

70.84±0.14

72.18±0.15

78.89±0.11

82.66±0.05

H7 61.88±0.16

73.62±0.05

76.46±0.04

80.60±0.06

85.18±0.18

88.26±0.01

H8 60.44±0.05

72.48±0.12

75.64±0.12

78.81±0.14

84.46±0.02

87.16±0.16

H9 58.64±0.25

70.24±0.12

73.18±0.15

76.64±0.04

82.24±0.06

85.58±0.05

H10 66.32±0.25

79.65±0.11

83.12±0.13

85.60±0.16

90.85±0.03

93.41±0.15

H11 56.56±0.16

69.84±0.02

72.68±0.03

74.16±0.12

81.84±0.16

84.43±0.16

H12 52.54±0.05

64.63±0.16

68.82±0.15

70.68±0.05

76.46±0.16

80.84±0.13

H13 64.32±0.25

77.41±0.25

84.82±0.05

87.64±0.16

91.42±0.14

99.89±0.19

H14 62.56±0.25

74.88±0.015

78.92±0.16

81.65±0.06

86.42±0.03

89.30±0.07

H15 50.48±0.04

62.26±0.16

70.48±0.16

72.61±0.01

80.42±0.02

83.34±0.04

185

Fig: 8.6 Water uptake of Famotidine mucoadhesive hydrogels

8.3.4 Evaluation of gel fraction

To extract the insoluble parts of hydrogels (i.e., the gelled part),

the prepared hydrogels were soaked in water for 48 h. Then they were

taken out and washed with hot water to remove soluble part, dried

and weighed. Gel fraction was determined from equation given

below182

Where, wo = weight of dried hydrogel after crosslinking.

we = weight of Sample after extraction of soluble parts.

186

8.3.5 Morphological evaluation

Size analysis by optical microscopy

After drying at 37ºC for 48 hours, the mean diameter of the

dried beads was measured by using an optical micrometer fitted with

a calibrated eye piece. The mean of 100 beads was noted as particle

size. The sizes of both dried and wet beads were measured. All reading

is average of three trials183.

Surface morphological studies by SEM analysis

The surface morphological studies and shape of the dried

hydrogels were examined by using scanning electron microscopy.

Fig: 8.7 (a & b) SEM Photographs of Formulation F1

187




188

8.3.6 Physicochemical evaluation

Percentage yield

Percentage yield was calculated by using equation given below

Drug content

100 mg equivalent weight of Famotidine hydrogels were

triturated using mortar and pestle. Then the triturated hydrogels were

placed in volumetric flask and the volume was made upto 100 ml with

pH 7.4 phosphate buffer solution and kept aside for 24 h. After

specified time intervals these hydrogels were filtered and make

necessary dilutions, then the absorbance were measured at 265 nm

spectrophotometrically184.

Drug entrapment efficiency

The 100 mg equivalent hydrogels were soaked and digested in

100 ml of pH 1.2 Hcl for 24 h and then the solution was filtered. The

absorbance was analysed spectrophotometrically at 265 nm after a

necessary dilutions. At least three determinations were carried out for

each formulation for the determination of drug entrapment185.

189

Table 8.6: Physicochemical evaluation of Famotidine hydrogels

Formulation code

%Yield

Drugcontent

(mg)

Drugentrapmentefficiency

Gelfraction

Size analysisDriedbeads

Wetbeads

H1 95.8±0.11

96.9±0.15

95.4±0.05

95.2±0.11

1.83±0.51

2.93±0.47

H2 98.4±0.15

96.2±0.12

93.2±0.15

92.6± 0.32

1.48±0.02

2.66±0.32

H3 97.3±0.16

94.4±0.11

92.4±0.11

91.8±0.41

1.65±0.04

2.51±0.21

H4 92.6±0.12

85.3±0.25

86.2±0.16

84.8±0.21

1.68±0.22

2.67±0.41

H5 93.2±0.25

86.8±0.05

86.8±0.08

85.6±0.15

1.52±0.12

2.58±0.22

H6 91.7±0.11

82.4±0.02

85.6±0.22

84.2±0.12

1.71±0.51

2.81±0.25

H7 96.8±0.18

93.2±0.22

91.6±0.02

90.7±0.02

1.64±0.11

2.61±0.05

H8 95.6±0.22

91.8±0.14

89.9±0.12

88.7±0.22

1.48±0.12

2.49±0.41

H9 94.7±0.02

90.1±0.15

88.2±0.18

87.6±0.51

1.69±0.32

2.78±0.21

H10 96.1±0.05

92.6±0.12

90.2±0.25

89.8±0.11

1.71±0.12

2.79±0.33

H11 95.2±0.15

91.4±0.16

89.4±0.08

88.2±0.23

1.52±0.36

2.62±0.42

H12 93.9±0.03

88.6±0.04

87.3±0.02

86.4±0.36

1.58±0.41

2.57±0.04

H13 99.6±0.12

97.6±0.22

96.8±0.12

95.7±0.14

1.79±0.22

2.84±0.02

H14 98.6±0.16

96.8±0.05

94.6±0.14

93.8±0.05

1.61±0.23

2.56±0.21

H15 97.8±0.14

95.3±0.04

92.8±0.16

91.4±0.08

1.62±0.15

2.56±0.51

8.4. In-vitro mucoadhesion test

The time taken for detachment of beads from sheep stomach

mucosa was measured186,187. This was evaluated by an in-vitro

adhesion testing method, known as wash off method. The

190

mucoadhesive property of beads was compared with that of a non-

adhesive material, ethylene vinyl acetate beads.

A piece of sheep stomach mucosa (2×2 cm) was mounted onto

glass slide (3×1 inch) with cyanoacrylate glue and one more glass slide

was connected with a support. The beads (50 no) were counted and

spread over the wet rinsed tissue specimen and immediately thereafter

the support was hung on the arm of a USP tablet disintegrating test

machine as shown in photographs in Figure 8.11 (a & b). By operating

the disintegration machine the tissue specimen was given a slow

regular up and down moment. The slides move up and down in the

test fluid at 37 ± 0.50C. The number of beads adhering to the tissue

was counted at 2 h intervals up to 8 h.

Fig: 8.11 (a & b) In-vitro mucoadhesion test by usingdisintegration apparatus

191

Table 8.7: Percentage mucoadhesion data for H1-H15

Formulation code % Mucoadhesion

H1 61

H2 62

H3 69

H4 63

H5 64

H6 62

H7 64

H8 63

H9 72

H10 73

H11 71

H12 74

H13 79

H14 71

H15 74

Fig: 8.12 Percentage of mucoadhesion of Famotidine hydrogels

192

8.5 In-vitro drug release and kinetic studies

8.5.1 In-vitro drug release studies

In-vitro drug release studies of Famotidine were performed using

USP dissolution test apparatus II (paddle method). The USP

dissolution apparatus was thermostated at temperature of 37±1ºC

and stirred at rate of 50 rpm. Each 100 mg equivalent hydrogels of

every formulation were taken and placed immersed in 900 ml of pH

1.2 Hcl buffer. The aliquots of 1 ml were withdrawn at time interval of

every one hour and filtered and replaced with equal volume of

dissolution medium. The sink condition was maintained throughout

the study. The samples were analyzed spectrophotometrically at

265 nm and finally cumulative amount of drug release at various time

intervals was calculated.

193

Table 8.8: In-vitro drug release and Higuchi’s data for H1-H5

Time inh

Sqrt oftime

Cumulative % release

H1 H2 H3 H4 H5

0 0 0 0 0 0 0

1 1.000 25.4 23.4 22.9 23.4 22.8

2 1.414 32.4 29.4 32.8 32.6 31.6

3 1.732 35.6 32.6 41.2 46.5 40.4

4 2.000 41.6 40.6 51.1 52.1 50.6

5 2.236 49.2 45.2 60.2 67.7 59.8

6 2.449 54.6 53.6 67.9 70.3 67.6

7 2.646 67.4 66.4 77.8 84.5 77.4

8 2.828 74.3 72.3 85.9 90.6 85.6

9 3.000 84.4 80.4 90.6 95.6 94.5

10 3.162 91.2 88.2 94.8 99.7 98.9

11 3.317 97.4 96.4 98.6 - -

Table 8.9: Peppa’s data for H1-H5

Log time Log cumulative % release

H1 H2 H3 H4 H5

0 1.405 1.369 1.360 1.369 1.358

0.301 1.511 1.468 1.516 1.513 1.500

0.477 1.551 1.513 1.615 1.667 1.606

0.602 1.619 1.609 1.708 1.717 1.704

0.698 1.692 1.655 1.780 1.831 1.777

0.778 1.737 1.729 1.832 1.847 1.830

0.845 1.829 1.822 1.891 1.927 1.889

0.903 1.871 1.859 1.934 1.957 1.932

0.954 1.926 1.905 1.957 1.980 1.976

1.000 1.960 1.945 1.977 1.999 1.995

1.041 1.989 1.984 1.994 - -

194

Fig: 8.13. In-vitro drug release data of H1-H5

Fig: 8.14. Higuchi’s plot of H1-H5

Fig: 8.15. Peppa’s plot of H1-H5

195


Time inh

Sqrt oftime


H6 H7 H8 H9 H10

0 0 0 0 0 0 0

1 1.000 20.4 18.2 23.1 25.5 24.8

2 1.414 24.2 26.4 32.5 34.1 31.8

3 1.732 29.8 34.5 42.7 44.5 40.6

4 2.000 38.6 43.7 51.4 53.7 47.2

5 2.236 48.9 50.2 60.5 62.1 53.8

6 2.449 59.2 59.1 68.2 72.5 62.8

7 2.646 71.6 62.3 78.4 83.6 72.6

8 2.828 87.5 73.8 86.2 86.8 80.6

9 3.000 93.6 87.5 94.9 93.9 88.4

10 3.162 98.7 93.6 98.8 97.9 96.5

11 3.317 - 98.5 - - -



H6 H7 H8 H9 H10

0 1.310 1.260 1.364 1.407 1.394

0.301 1.384 1.422 1.512 1.533 1.502

0.477 1.474 1.538 1.630 1.648 1.609

0.602 1.587 1.640 1.711 1.730 1.674

0.698 1.689 1.701 1.782 1.793 1.731

0.778 1.772 1.772 1.834 1.860 1.798

0.845 1.855 1.794 1.894 1.922 1.861

0.903 1.942 1.868 1.936 1.939 1.906

0.954 1.971 1.942 1.977 1.973 1.946

1.000 1.994 1.971 1.995 1.991 1.985

1.041 - 1.993 - - -

196




197


Time inh

Sqrt oftime


H11 H12 H13 H14 H15

0 0 0 0 0 0 0

1 1.000 21.6 20.2 28.6 22.9 25.2

2 1.414 29.2 28.8 34.8 28.8 32.1

3 1.732 31.4 30.2 40.6 38.5 40.5

4 2.000 38.6 37.4 46.2 44.4 47.4

5 2.236 47.8 46.4 52.6 54.3 54.1

6 2.449 59.9 58.6 59.8 60.8 69.8

7 2.646 74.8 72.4 68.9 76.4 80.9

8 2.828 89.6 88.9 76.2 83.6 87.4

9 3.000 94.3 94.3 86.6 89.9 90.4

10 3.162 98.4 98.8 92.6 95.2 96.3

11 3.317 - - 99.6 - -



H11 H12 H13 H14 H15

0 1.334 1.305 1.456 1.360 1.401

0.301 1.465 1.459 1.542 1.459 1.507

0.477 1.497 1.480 1.609 1.585 1.607

0.602 1.587 1.573 1.665 1.647 1.676

0.698 1.679 1.667 1.721 1.735 1.733

0.778 1.777 1.768 1.777 1.784 1.844

0.845 1.874 1.860 1.838 1.883 1.908

0.903 1.952 1.949 1.882 1.922 1.942

0.954 1.975 1.975 1.938 1.954 1.956

1.000 1.993 1.995 1.967 1.979 1.984

1.041 - - 1.998 - -

198




199

8.5.2 In-vitro kinetics studies

Data of in-vitro release were fit into different equations and

kinetic models to explain the release kinetics of Famotidine from the

mucoadhesive hydrogels. The kinetic models used were a zero-order

equation, higuchi’s model and peppa’s models159-161. The obtained

results in these formulations were plotted in various model treatment

are as follows. I.e. Cumulative percentage release of drug Vs Square

root of time (Higuchi’s) and Log cumulative percentage release Vs Log

time (Peppas). To know the mechanism of drug release of Famotidine

from the buccal tablets the drug release data was fit into Higuchi’s

models.

To find out the mechanism of drug release from hydrophilic

matrices, the in-vitro dissolution data of each formulation with

different kinetic drug release equations. Namely Zero order: Q=K0t;

Higuchi’s square rate at time: Q=KHt1/2 and Peppas: F=Kmtn, where Q

is amount of drug release at time t, F is Fraction of drug release at

time t, K0 is zero order kinetic drug release constant, KH is Higuchi’s

square root of time kinetic drug release constant, Km is constant

incorporating geometric and structural characteristic of the tablets

and n is the diffusion exponent indicative of the release mechanism.

The correlation coefficient values (r) from Higuchi’s model indicate the

kinetic of drug release and diffusion exponent values (n) from Peppas

model indicate the mechanism of drug release.

200

Fig: 8.22. Comparative in-vitro drug release data of H1-H15

Fig: 8.23. Comparative Higuchi’s data of H1-H15

201

Fig: 8.24. Comparative Peppa’s data of H1-H15

Table 8.14: Diffusion characteristics of Formulations T1-T16

Formulationcode

Correlation coefficient values (r) Diffusion exponentvalue (n)Zero Order Higuchi’s Model

H1 0.9943 0.9707 0.5893

H2 0.9712 0.9988 0.6219

H3 0.9803 0.9806 0.6414

H4 0.9750 0.9968 0.6629

H5 0.9985 0.9943 0.6667

H6 0.9775 0.9897 0.7614

H7 0.9928 0.9862 0.7251

H8 0.9880 0.9916 0.6558

H9 0.9821 0.9974 0.6199

H10 O.9964 0.9913 0.6079

H11 0.9772 0.9896 0.7149

H12 0.9892 0.9996 0.7371

H13 0.9908 0.9915 0.5434

H14 0.9907 0.9940 0.6630

H15 0.9861 0.9949 0.6298

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8.6 Comparison of in-vitro drug release with marketed product

The optimized formulation H13 in-vitro drug release data were

compared with the marketed tablet dosage form. The prepared

hydrogels showed the controlled as well as promised release than the

marketed formulations. The results were presented in table no 8.15

and represented in figure 8.25

Table 8.15: Comparison of in-vitro drug release data(H13 vs Marketed product)

Time in

h

H13 Cumulative

% Drug Release

Marketed product

Cumulative % Drug

Release

1 28.6 58.8

2 34.8 82.4

3 40.6 98.2

4 46.2 -

5 52.6 -

6 59.8 -

7 68.9 -

8 76.2 -

9 86.6 -

10 92.6 -

11 99.6 -

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Fig: 8.25. Comparative in-vitro dissolution data

(H13 vs Marketed product)

8.7 In-vivo drug release study

Six male New Zealand white rabbits (2-2.5 kg) were selected for

the in-vivo study, which was already checked for absence of any

diseases. The fore limbs and hind limbs were tied into the iron rod of

the mini operation table; so that rabbit was in dorsal

position. The optimized formulation H13 was administered orally.

Dextrose solution was transfused continuously throughout the

period of study. Periodically 1 ml of blood sample was taken

by syringe, which already contained 1 ml of heparin solution

to prevent blood clotting. These blood samples were

subjected for centrifuging at 2,500 rpm for about 30 minutes.

1 ml of supernatant was taken, and after suitable dilution,

analyzed at 265 nm using UV spectrophotometer.

204

The study was approved by the Ethical committee of

Annamacharya College of pharmacy, Rajampet, Andhra Pradesh,

India, (Reg. No.1220/a/08/CPCSEA/ANCP/IAEC/14/2010).

Table 8.16: In-vivo drug release data for formulation H13

Time in h Cumulative %

drug release

1 12.66

3 21.68

6 45.83

9 68.32

11 91.66

Fig: 8.26. In-vivo drug release plot of H13

8.8. In-vitro – In-vivo Correlation

The data obtained from the in-vitro drug release of formulation

H13 is correlated with in-vivo drug release in rabbit followed by

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diffusion of drug from H13. The correlation of data was carried out by

plotting graph in excel. The graph was plotted by taking in-vitro

cumulative percentage of drug release on x-axis and in-vivo

cumulative percentage of drug release on y-axis for the same period of

time.

Table 8.17: In-vitro and in-vivo correlation data of H13

Time in h Cumulative %drug release

(in-vitro)

Cumulative %drug release

(in-vivo)0 0 0

1 28.6 12.66

3 40.6 21.68

6 59.8 45.83

9 86.6 68.32

11 99.6 91.66

Fig: 8.27. In-vitro and In-vivo correlation plot

206

8.9 Stability studies as per ICH

The formulation H13 was selected and the stability studies were

carried out at accelerated condition of 40±20C, 75±5% RH conditions,

stored in desiccators, the hydrogels were packed in muslin cloth

which is covered by aluminium foil and kept in above said condition

for period of three months. The hydrogel beads were analyzed

periodically for their morphology, swelling ratio, water up take, drug

content, in-vitro mucoadhesion and in-vitro drug release. Results were

analyzed by One-way ANOVA followed by Tukey’s test. Differences

were considered statistically significant at p<0.05.

8.10 Results and discussion

The mucoadhesive hydrogels of Famotidine were prepared by

physical cross linking orifice ionic gelation process with varying

proportions of polymers like HPMC-K100, SCMC and carbopol in

combination with sodium alginate. The 2% Cacl2 solution served for

the purpose of cross linking. The composition of mucoadhesive

hydrogels were shown in the table 8.2 and the formulations before

and after drying were shown in the figure 8.2, 8.3, 8.4 of H1, H9 and

H13 respectively.

Evaluation of Famotidine mucoadhesive hydrogels

The all prepared formulation of mucoadhesive hydrogels of

Famotidine were dried at room temperature and the dried beads were

evaluated for its micromeritic properties which includes angle of

207

repose, bulk density, tapped density, Carr’s Index and Hausner’s

ratio. The obtained results were presented in the table 8.3.

Equilibrium Swelling Ratio (ESR)

The swelling behavior of the polymer was reported to be crucial

for its mucoadhesive character. Hence the polymers were shown

enough mucoadhesive character to provide the controlled release of

Famotidine towards the mucosal membrane. The adhesion increases

with the degree of hydration till the point of disentanglement at the

polymer tissue surface, which leads to abrupt drop in adhesive

strength due to over hydration. The formulation H13 shows the

maximum swelling at the end of 6 h than the other formulation which

is due to more concentration of HPMC with addition of carbopol and

excess hydration of polymer. The formulation H13 having sodium

alginate, HPMC and carbopol in the ration of 1:1.5:0.5 respectively.

The data of swelling ratio were presented in the table 8.4 and in figure

8.5.

Water uptake studies

The water uptake of polymers is playing very significant role for

swelling and drug release. The drug release followed by diffusion

mechanism by the creation of pore in the hydrogel beads only after

absorbing the body fluids. The water uptake of polymer mainly

depends on the hydrophilic nature. The formulation H13 shows

maximum uptake due to high proportions of HPMC. The data of water

208

uptake of all the formulations were presented in the table 8.5 and the

figure were shown in 8.6.

Gel fraction

Gel fraction is carried out to determine the gelled part and

separate the water soluble part. The data of gel fraction were

presented in the table 8.6.

Physicochemical evaluation

The all formulated hydrogels were evaluated for its

physicochemical characters like percentage yield, drug content, drug

entrapment efficiency and size analysis. The obtained results were

present in the table 8.6.

In-vitro mucoadhesion test

The in-vitro mucoadhesion test was performed by wash-off test

which indicate the ability of the formulation adhering over the

mucosa. The role of polymer is very crucial for the mucoadhesion. All

the polymers were chosen for formulation is showing good adhesion.

The data of percentage of mucoadhesion were presented in the table

8.7 and represented in the figure 8.12.

In-vitro drug release and kinetic studies

Distinguishable difference was observed in the release of

Famotidine in all formulations. The in-vitro drug release and Higuchi’s

plot have shown that the drug release followed zero order kinetics,

which was known from the regression value (r). Sodium alginate is

present in an ionized state, and as a result, the polymeric network

209

gets loosened comparatively, attributing for the higher drug release.

The drug release mainly depends upon the degree of swelling, water

uptake based on hydrophilic nature of the polymer, percentage of

mucoadhesion. The data of in-vitro release of all the formulation were

presented in the table 8.8 to 8.13 and represented in the figure 8.13 to

8.21.

Data of in-vitro release were fit into different equations and

kinetic models to explain the release kinetics of Famotidine from the

buccal tablets. The kinetic models used were a zero order equation,

Higuchi’s model and Peppas models. The obtained results in these

formulations were plotted in various model treatments as cumulative

percentage release of drug versus square root of time (Higuchi’s) and

log cumulative percentage release versus log time (Peppas).

To find out the mechanism of drug release from hydrophilic

matrices, the in-vitro dissolution data of each formulation were

calculated with different kinetic drug release equations. The

mechanism of drug release by Peppas model indicates the non-Fickian

evidenced with diffusion exponent values (n). The in-vitro drug release

of optimized formulation was compared with the release pattern of

marketed product and the data are present in table 8.14, represented

in figure 8.25.

In-vivo drug release study

Based on the in-vitro evaluation study the prepared

mucoadhesive hydrogels of Famotidine (H13) was selected for in-vivo

210

evaluation by applying the hydrogels to rabbits, one of its as control

untreated. The in-vivo studies of optimized formulation shows zero

order release pattern. The results were presented in the table 8.15 and

represented in figure 8.23.

The correlation of drug release was carried out for the

therapeutic efficacy of a pharmaceutical formulation and is governed

by the factors related to in-vitro and ex-vivo, in-vitro and in-vivo

characteristics of the drug. The drug release follows zero order,

showing the correlation coefficient value 0.983, the data were

presented in the table 8.16 and shown in figure 8.27.

Stability studies as per ICH

The formulation H13 was selected and the stability studies were

carried out at accelerated condition of 40±20C, 75±5% RH conditions,

stored in desiccators, the hydrogels were packed in muslin cloth

which is covered by aluminium foil and kept for period of three

months. The hydrogel beads were analyzed periodically for their

morphology, swelling ratio, water up take, drug content, in-vitro

mucoadhesion and in-vitro drug release. Results were analyzed by

One-way ANOVA followed by Tukey’s test. Differences were considered

statistically significant at p<0.05.

8.11 Conclusion

The Famotidine mucoadhesive hydrogel beads were prepared by

orifice ionotropic gelation method is well suited for the successive

formulations. The polymers and solvent were chosen has showed more

211

percentage yield of hydrogels. The polymer used as sodium alginate,

HPMC K100, SCMC and carbopol for the formulation of hydrogels

shows no significant interaction with drug evidenced by Physical

observation, DSC and FTIR studies. The physicochemical properties

were characterized by Swelling index, Water uptake studies, Gel

fraction, Size analysis, percentage yield, Drug content and Drug

entrapment efficiency. The in-vitro drug release studies were

performed all the formulations shows the controlled release pattern of

drug up to 11 h. Surface morphological studies by SEM analysis

obtained showed good spherical shape and also surface morphological

characters. In-vitro drug release was also compared with that of

marketed product. The satisfactory results were obtained in all

prepared formulations and based on the results H13 was best one

when compared to other. Good correlation was observed between in-

vitro and in- vivo profile, revealed the ability of the formulation to

reproduce the in-vitro release pattern. Hence Famotidine oral

mucoadhesive hydrogel beads could be promising one as they,

increase bioavailability, minimize the dose, reduces the side effects

and improve patient compliance and also Famotidine might be a right

and suitable candidate for oral controlled drug delivery via

mucoadhesive hydrogels.

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