International Journal of Universal Pharmacy and Bio Sciences...

24 | P a g e International Standard Serial Number (ISSN): 2319-8141

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International Journal of Universal Pharmacy and Bio Sciences 10(2): March-April 2021

INTERNATIONAL JOURNAL OF UNIVERSAL

PHARMACY AND BIO SCIENCES IMPACT FACTOR 4.018***

ICV 6.16*** Pharmaceutical Sciences Research Article……!!!

DESIGN AND CHARACTERIZATION OF FLOATING IN SITU GEL

CONTANING ANTIHYPERTENSIVE DRUG

Srilatha K. S*1, Dr.Shyam Nandan Yadav

2 C.Geethapriya

3 Vinitha.R

1

1*Department of Pharmaceutics, R R College of Pharmacy, Bangalore, India.

2Department of Pharmacy Practice, R R College of Pharmacy, Bangalore, India.

3Department of Pharmaceutical chemistry, R R College of Pharmacy, Bangalore, India.

KEYWORDS:

Diltiazem HCL, Anti-

hypertensive agent, In

situ gelling systems.

For Correspondence:

Srilatha K. S*

ADDRESS:

Department of

Pharmaceutics, R R

College of Pharmacy,

Bangalore, India.

ABSTRACT

The purpose of present research work was to prepare and evaluate oral

floatable in situ gel of Diltiazem HCL, it is a calcium channel blocker,

which interfere with the movement of calcium into heart muscle cell

and smooth cells of arteries, this action relaxes blood vessels (causing

them to widen) which lowers the blood pressure, increase the blood

Supply to the heart and decreases the hearts overall work load.

Formulation was prepared by sodium alginate and gelrite. The

prepared formulations were in liquid state and becomes gel when it

enters in to the acidic environment (pH 1.2). Formulation was

evaluated for physicochemical parameters like pH, gelling capacity,

gel strength, viscosity, in vitro floating ability, drug content

uniformity, and in vitro drug release study. The best formulation was

selected and stability studies were performed as per ICH guidelines.

Thus, study concludes that the floating in situ gelling system of

Diltiazem HCL could be used for controlled drug delivery system.



INTRODUCTION:

In-situ gel forming systems have been widely investigated as vehicles for sustained drug delivery. This

interest has been sparked by the advantages shown by in-situ forming polymeric delivery systems such

as ease of administration and reduced frequency of administration, improved patient compliance and

comfort. In-situ gel formation occurs due to one or combination of different stimuli like pH change,

temperature modulation and solvent exchange. So, In-situ gelling system via different route such as

oral, nasal and ophthalmic etc, can be formulated. Various natural and synthetic polymers such as

Gellan gum, alginic acid, xyloglucan, pectin, chitosan, poly (DL lactic acid), poly (DL-lactide-co-

glycolide) and poly- caprolactone are used for formulation development of in-situ forming drug

delivery systems. Gastro retentive in situ gelling system helps to increase bioavailability of drug

compared to conventional liquid dosage form. The gels formed from in-situ gelling system, being

lighter than gastric fluids, floats over the stomach contents or adhere to gastric mucosa due to presence

of bio adhesive nature of polymer and produce gastric retention of dosage form and increase gastric

residence time resulting in prolonged drug delivery in gastrointestinal tract.

FIGURE 1: PHYSIOLOGY OF STOMACH

Materials and methodology

Diltiazem HCl was obtained from Sun pharmaceuticals, Sodium alginate, Calcium carbonate Gelrite

and rest of the chemicals were obtained from laboratory grade.

1)Determination of absorption maximum (λmax) of Diltiazem HCL using Spectrophotometer.

Absorption maxima may be defined as the wave length at which the substance produces the maximum

absorption. Absorbance maximum for a drug was determined in 0.1N HCL buffer. A solution of



Diltiazem HCL containing 10 mcg/ml was prepared in 0.1 N HCL and scanned in the range 200nm-

400nm against 0.1N HCL respectively as blank using UV spectrophotometer.

2) CONSTRUCTION OF STANDARD CALIBRATION CURVE FOR DILTIAZEM HCL

a) Preparation of 0.1 N HCL 8.5 ml of concentrated hydrochloric acid was diluted to 1000 ml with

distilled water.

b) Preparation of standard solution of Diltiazem HCL using 0.1N HCL (pH1.2) solution.

Stock I:

Accurately weighed 100 mg of Diltiazem HCL was transferred to a 100 ml volumetric flask. The

volume was made up to the mark by using 0.1 N HCL at room temperature (1000mcg/ml).

Stock II:

From the above stock solution1 10 ml was diluted to 100ml using 0.1 N HCL in volumetric flask

(100mcg/ml). From the above stock solution II, serial dilutions were made to obtain 10, 20, 30, 40 and

50 mcg/ml solution using 0.1 N HCL as diluents. Then the absorbance of these solutions was read at

237 nm using UV- visible spectrometer against using against 0.1 N HCL as blank and standard graph

was plotted using these values.

3) Preparation of In-situ gel of Diltiazem HCL (DHCL)

Active material (DHCL) was passed through sieve no. 60 while other inactive ingredients were passed

through sieve no. 40, and then aqueous solution of Gelrite was prepared in deionised water , solution

were heated up to 600C,after cooling to below 40

0C DHCL was added slowly to the above solution

while stirring on a magnetic stirrer so that there was proper and homogeneous dispersion of the drug. In

other beaker sodium alginate solution were prepared by heating up to 600C,after cooling to below 40

0C,

both solutions were mixed while stirring on magnetic stirrer. Then appropriate amount calcium

carbonate was added while stirring. Finally, the mixture was mixed well to get the final preparation.

Table no 1: Composition of floating in situ gel of Diltiazem HCL

F 1 F 2 F 3 F 4 F 5 F 6 F 7 F 8 F 9

Diltiazem HCL (mg) 300

300

300

300

300

300

300

300

300

Sodium Alginate

(mg)

750

750

750

1000

1000

1000

1500

1500

1500

Gelrite 400 400 400 400 400 400 400 400 400

Calcium carbonate

(mg) 500 750 1000 500 750 1000 500 750 1000

Sodium citrate (mg) 500 500 500 500 500 500 500 500 500

De-ionized water Qs

(ml) 100 100 100 100 100 100 100 100 100



EVALUATION OF FORMULATION

1) pH measurement

pH of the each prepared gelrite and sodium alginate based in-situ gel solution of Diltiazem HCL were

checked used a calibrated pH meter at 25 0

C.

2) Determination of drug content

Prepared 10 ml of in-situ gel were measured and transferred to 100ml of volumetric flask. To this 70 ml

0.1 N HCL was added and sonicated for 30 minutes. Volume was adjusted to 100ml. Complete

dispersion of contents were ensured visually and filtered using Whatman filter paper. From this solution

10 ml of a sample was withdrawn and diluted to 100 ml with 0.1N HCL. Contents of Diltiazem HCL

were determined spectrophotometrically at 237 nm using UV- spectrophotometer.

3) Viscosity

Viscosity of prepared in-situ gel was determined by using Brookfield viscometer DV-III using spindle

number 21 with cup and bob setting and velocity increased to 10 to 100 rpm. Temperature of each

aliquot of the sample was kept at 27 ± 10 °C during each measurement.

4) Floating behaviour.

Floating study of prepared in situ gel was carried out using 0.1 N HCL (pH 1.2). The temperature of

medium was kept at 37°C .10 ml of prepared in situ gel was introduced into the dissolution vessel

containing medium without much disturbance. The time taken for the formulation to emerge on the

medium surface (floating time) and the time the formulation constantly floated on surface of the

dissolution medium (duration of floating) were noted.

5) In-vitro gelling capacity.

The formulations for their in-vitro gelling capacity by visual method, solution of in situ gel forming

drug delivery system were prepared. The in-vitro gelling capacity of prepared formulations was

measured by placing 5ml of the gelation solution (0.1N HCL, pH 1.2) in a test tube and maintained

temperature at 37± 10 °C temperature. The formulations were transferred in such a way that if the

pipette is placed at surface of fluid in the test tube and the formulation in the pipette. As the solution

comes in to the contact with gelation solution, it was immediately converted stiff gel like structure. The

gelling capacity of solution was evaluated on the basis of stiffness of formed gel and time period for

which the formed gel remains as such. The in-vitro gelling capacity was graded in three categories on

the basis of gelation time and time period for which the formed gel remains.

(+) Gels after few minutes, dispersed rapidly.

(++) Gelation immediate remains for 12 hours.

(+++) Gelation immediate remains for more than 12 hours.



6) Measurement of water uptake by gel

The water uptakes by gel of the selected formulation of gelrite and sodium alginate were determined by

a simple method. In this study the in-situ gel formed in 40ml of 0.1 N HCL (pH 1.2) was used. From

each formulation the gel portion from the 0.1 N HCL was separated and the excess Hcl solution was

blotted out with a tissue paper. The initial weight of the gel taken was weighed and to this gel 10 ml of

distilled water was added and after every 30 minutes of the interval water was decanted and the weight

of the gel was recorded and the difference in weight was calculated and reported.

7) In-vitro drug release study

The study of Diltiazem release from the in-situ gelling preparation was carried out by using dissolution

test apparatus USP type II (paddle method) at a rate of 50 rpm. This speed was slow enough to avoid

the breaking of gelled formulation and the mild agitation conditions believed to exist in vivo. The

dissolution medium used was 900 ml of 0.1 N HCL (pH 1.2) and temperature was maintained at 37°C.

10 ml sample was withdrawn from dissolution apparatus at every 1-hour intervals for analysis and

replaced the same amount of the pre-warmed (37°C) fresh medium. Contents of Diltiazem HCL were

determined spectrophotometrically at 237 nm using a spectrophotometer.

8) Drug release kinetic studies

The release kinetics studies were done by various mathematical models (zero order, first order,

Higuchi’s square root, and Pappas equation). The model that best fits the release data is selected based

on the correlation co-efficient (r) value in various models. The model that gives high “r” value is

considered as the best fit of the release data. The release constant was calculated from the slope of the

appropriate plots, and the regression coefficient (r2) was determined.

9)Stability studies

The purpose of stability study is to provide evidence that the quality of a drug substance or drug

product will not vary with time under the influence of a variety of environmental factors such as

temperature, humidity and light during the storage period before consumption of the product. Stability

studies were performed for the formulation which was selected as best as per ICH guidelines. The

formulation was sealed in an aluminium foil and stored at specified condition 25±2ºC and 60± 5% RH

for 3 months. Samples were periodically taken and evaluated for physicochemical parameter, drug

content and in vitro release using the same procedure mentioned previously.



Table-2: Standard plot of Diltiazem HCL in 0.1 N HCL at 237 nm.

Concentration (mcg/ml) Absorbance(nm)

0 0

10 0.116

20 0.266

30 0.338

40 0.450

50 0.566

60 0.678

FIGURE2 Standard plot of Diltiazem HCL

FIGURE 3: FTIR of Diltiazem HCL



FIGURE4: FTIR of Diltiazem HCL with excipient.

FIGURE 5: Floating In situ of Diltiazem HCL



Table-3Drug content estimation in situ gelling formulations batch F 1 to F 9

Formulations Drug content (%)

F 1 96.91 ± 0.47

F 2 98.95 ± 0.57

F 3 96.91 ± 0.46

F 4 97.41 ± 0.87

F 5 98.92 ± 0.27

F 6 97.92 ± 0.43

F 7 97.41 ± 0.23

F 8 99.22 ± 0.47

F 9 99.23 ± 0.48

Table-4: Evaluation of pH, floating lag time and floating duration

Formulations pH Floating lag time

(s)

Floating duration

(h)

F 1 6. 78 ± 0.032 18 ± 3.2 9

F 2 6. 98 ± 0.012 17 ± 1.2 9

F 3 6. 56 ± 0.031 19 ± 3.4 9

F 4 6. 79 ± 0.121 14 ± 5.2 12

F 5 6. 98 ± 0.456 13 ± 3.6 12

F 6 6. 77 ± 0.761 12 ± 4.2 12

F 7 6. 68 ± 0.789 11 ± 6.2 >12

F 8 6. 32 ± 0.068 10 ± 3.1 >12

F 9 6. 12 ± 0.124 8 ± 3.3 >12

Table-5: Evaluation of In vitro gelling capacity, viscosity and density

Formulations In vitro gelling

capacity Viscosity (Cps) Density(gm/cm2)

F 1 + 145 ± 0.23 0.837 ± 0.5

F 2 + 155 ± 0.20 0.643 ± 0.61

F 3 ++ 160 ± 0.44 0.737 ± 0.72

F 4 ++ 172 ± 0.54 0.698 ± 0.53

F 5 +++ 179 ± 0.66 0.737 ± 0.32

F 6 +++ 185 ± 0.45 0.641 ± 0.53

F 7 +++ 189 ± 0.67 0.842 ± 0.61

F 8 +++ 191 ± 0.87 0.8673± 0.43

F 9 +++ 195 ± 0.17 0.8916± 0.43

*Average of three trials (Average + S.D)

(+) Gels after five min, dispersed within 8 hr, (++) Gels within 60 sec and retains gel structure for 12

hr, (+++) Gels immediately and retains gel structure for more than 12hrs



Table-6: Evaluation of gel strength.

Formulations Gel strength (gm/cm2 )

F 1 20.17 ± 0.20

F 2 19.27 ± 0.42

F 3 32.62 ± 0.30

F 4 53.96 ± 0.31

F 5 33.54 ± 0.29

F 6 55.17 ± 0.58

F 7 61.37 ± 0.32

F 8 63.57 ± 0.24

F 9 68.17 ± 0.63

Table-7: In-vitro drug release studies from F 1 to F 9

Ti

me

(hr)

F 1 F 2 F 3 F 4 F 5 F 6 F 7 F 8 F 9

1 57.05±1

.96

47.66±1

.02

53.65±0

.02

49.69±0

.34

46.27±0

.27

49.47±0

.36

50.87±0

.16

48.81±2

.16

46.82±2

.15

2 63.34±1

.24

61.09±1

.33

62.09±1

.15

60.65±1

.95

54.98±1

.96

53.31±1

.52

52.71±1

.36

51.11±1

.22

50.13±1

.29

3 70.05±1

.32

70.13±1

.99

72.24±0

.99

66.24±0

.32

58.24±0

.04

56.49±0

.35

56.19±0

.68

53.15±0

.39

53.28±0

.38

4 73.05±1

.22

73.23±1

.24

78.63±1

.56

70.64±1

.47

63.67±0

.47

60.87±0

.85

60.07±0

.74

56.07±0

.78

57.22±0

.74

5 78.06±1

.06

79.57±1

.77

80.66±1

.23

78.98±1

.62

68.34±1

.10

62.35±2

.10

63.20±1

.10

58.27±3

.10

59.88±3

.18

6 85.12±1

.96

83.16±1

.96

83.98±1

.76

83.98±1

.76

72.55±1

.23

68.56±7

.23

67.57±0

.23

61.37±0

.20

63.32±0

.27

7 94.44±1

.46

92.24±1

.56

94.23±1

.02

88.54±1

.68

81.66±1

.24

72.69±1

.94

79.68±1

.96

64.12±1

.97

65.18±1

.94

8 98.27±1

.16

98.20±1

.40

98.57±1

.43

92.02±1

.05

84.66±1

.80

87.68±1

.75

82.61±1

.02

68.62±1

.02

67.11±1

.05

9 94.65±1

.28

88.57±1

.31

98.87±0

.31

95.82±0

.34

71.87±0

.63

71.96±0

.69

10 95.22±1

.65

74.25±0

.76

74.25±0

.75

11 85.56±0

.48

81.86±0

.49

*Average of three trials (Average ± S.D.)



Table-8: Drug release kinetic studies from F 1 to F 9

Formulations Zero order

R2

First order

R2

Higuchi R2

F 1 0.9778 0.9502 0.9738

F 2 0.9818 0.9528 0.9672

F 3 0.9814 0.9703 0.9736

F 4 0.9254 0.8153 0.9918

F 5 0.9349 0.9044 0.9941

F 6 0.9489 0.9151 0.9877

F 7 0.9536 0.9092 0.9863

F 8 0.9613 0.9638 0.9873

F 9 0.9636 0.9832 0.9885

Table-9: Drug release kinetic studies from F 1 to F 9 Formulations Korsmeyer -Peppas R

2 Korsmeyer -Peppas n

F 1 0.9872 0.6825

F 2 0.9848 0.6787

F 3 0.9877 0.6778

F 4 0.9483 0.6876

F 5 0.9563 0.6883

F 6 0.9606 0.6827

F 7 0.9612 0.6855

F 8 0.9730 0.6900

F 9 0.9793 0.6840

Table-10: Accelerated stability study at 40± 2 °Cand 75± 5%RH of the Formulation F8

Physicochemical

parameters

Initial 30 th

day 60 th

day 90 th

day

PH

6.32±0.068 6.31±0.060 6.32±0.088 6.32±0.096

Viscosity 191±0.87 192±0.86 195±0.88 193±0.99

Drug content 99.22±0.49 99.01±0.56 99.36±0.88 98.22±0.33

Table-11: Accelerated stability study at 40± 2 °Cand 75± 5%RH of the Formulation F9

Physicochemical

parameters

Initial 30 th

day 60 th

day 90 th

day

PH

6.12±1.24 6.12±0.88 6.12±0.994 6.33±0.942

Viscosity 195±0.17 195±0.76 195±0.98 195±0.84

Drug content 99.23±0.48 99.23±0.56 98.39±0.88 99.98±0.67

Table-12: In vitro drug release of formulation F8 after stability.

Time in hrs Initial 30 th

day 60 th

day 90 th

day

1 48.81±2.16 47.81±2.07 47.33±1.07 48.38±1.22

2 51.11±1.22 52.11±1.33 52.45±1.34 52.85±1.86

3 53.15±0.39 53.15±0.44 53.15±0.44 53.15±0.56

4 56.07±0.78 55.07±0.77 55.88±0.12 56.89±0.22



5 58.27±3.10 57.88±3.56 58.88±1.56 58.94±2.50

6 61.37±0.20 62.34±0.24 61.34±0.55 61.88±0.65

7 64.12±1.97 65.12±1.96 65.65±2.96 65.89±1.96

8 68.62±1.02 66.63±1.54 67.63±2.56 67.64±1.56

9 71.87±0.63 72.80±0.44 71.80±0.42 71.82±0.43

10 74.25±0.76 73.44±0.78 74.44±0.84 73.12±0.08

11 85.56±0.48 86.57±0.55 86.86±0.56 86.42±0.01

Table-13: In vitro drug release of formulation F9 after stability.

Time in hrs Initial 30 th

day 60 th

day 90 th

day

1 46.82±2.15 46.56±0.15 45.45±0.16 45.23±0.22

2 50.13±1.29 51.13±1.22 51.22±1.36 51.96±1.44

3 53.28±0.38 53.99±0.24 53.26±0.29 53.05±3.29

4 57.22±0.74 57.27±0.88 57.39±0.63 57.36±0.45

5 59.88±3.18 58.56±0.18 58.06±0.22 58.96±0.93

6 63.32±0.27 63.22±0.66 63.06±0.35 63.96±0.65

7 65.18±1.94 65.63±0.95 65.12±0.63 65.22±0.54

8 67.11±1.05 67.23±1.23 67.03±0.23 67.96±0.69

9 71.96±0.69 71.69±0.32 70.62±0.02 70.85±0.45

10 74.25±0.75 73.26±0.76 74.27±0.88 74.65±0.78

11 81.86±0.49 82.86±0.55 82.56±0.32 82.99±0.68

CONCLUSION:

In the present study, an attempt was made to formulate and evaluate oral floating in-situ gel of

Diltiazem HCL which is an antihypertensive drug. Diltiazem HCL is well absorbed from stomach and

first part of the small intestine, Pre-formulation studies and estimation of drug by UV visible

spectrophotometer was carried out. The possible interaction between drug and polymer were studied by

performing FTIR study no interactions were observed p H

measurement, determination of drug content,

viscosity, floating behaviour, In vitro gelling capacity, measurement of water up taken by the gel, In

vitro drug release kinetic studies and stability studies were performed. Results were in the limit, The

optimum formulation F8 and F9 were selected based on good gelling capacity, viscosity and drug

content. Cumulative drug release was 71.87±0.63 and 71.96± 0.69 after 8hrs, which may give the

complete release in 12hrs.So F8 and F9 were selected as best formulations. All the formulations

followed non Fickian transport as the R 2 values were in the range of 0.9483-0.9848 and n=0.6778-0.

6900.Stubility study showed that there were no significant changes were found for the parameters

considered after 3 months. Thus floating in situ gelling system of Diltiazem HCL can be formulated

as sustained drug delivery of drug and recommended for further studies.



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