107

CHAPTER - 6

DEVELOPMENT AND EVALUATION OF CITICOLINE

CONTROLLED RELEASE TABLETS

6.1 MATERIALS AND EQUIPMENTS

Table 6.1: List of Materials used in research work

Name of the Material Manufacturer

Citicoline Sodium IH Micro Labs, Bangalore, India.

Microcrystalline Cellulose

( Avicel PH-101) USP/NF

FMC Bio Polymer, Ireland.

Hypromellose (Methocel K100M) USP/NF

Dow Chemicals, Germany.

Hydroxy propyl cellulose (HF) USP/NF

Ashland Inc. SA

Ammonio Methacrylate co-polymers (Eudragit RLPO) USP/NF

Evonik industries, Germany.

Ammonio Methacrylate co-polymers

(Eudragit RSPO) USP/NF

Evonik industries, Germany.

Acetone (AR Grade) Rankem, Mumbai.

Isopropyl alcohol (AR Grade) Rankem,Mumbai.

Colloidal Silicon Dioxide USP/NF Evonik industries, Germany.

Magnesium Stearate USP/NF Ferro corporation, Cleveland

Talc USP/NF Luzenca Pharma,Italy

Titanium Dioxide USP/NF Kronos,Germany

Triacetin (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

Potassium dihydrogen Orthophosphate (AR Grade)

Merck Specialties Pvt. Ltd, Mumbai.

Sodium Hydroxide (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

Tetra butyl ammonium hydrogen sulphate (AR Grade)

Merck Specialties Pvt. Ltd, Mumbai.

Tri ethyl amine (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

Acetic acid (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

Methanol (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

Hydrochloric acid (AR Grade) Merck Specialties Pvt. Ltd, Mumbai.

108

Table 6.2: List of Equipments Used in the Research Work

Equipment Name Manufactured By

Electronic Weighing Balance Mettler Toledo (AB104), Germany.

Hot air oven Innovative instruments, New

Delhi

Sieves Jayant Scientific Ind.,Bombay

Compression Machine (8 Station) Cadmach,Ahemadabad

Conentional coating Pan Innovative instruments, New

Delhi

Digital Vernier Calipers Mitutoyo (CD-8CSX), China.

Friability Apparatus Electrolab EF – 2W, Mumbai.

Hardness Tester Dr. Schleuniger (6D), Germany.

Dissolution Apparatus TDT-08L, Electrolab, Mumbai.

Sonicator Power sonic 505, India.

HPLC Waters, USA.

FT-IR Perkin Elmer,Japan.

Vortex Mixer Spinex, India.

Stability Chamber Mack, Mumbai.

DSC Mettler Toledo,star DSC21, USA.

UV visible spectrophotometer Analytikjena Specord 210

Overhead 3-blade medium duty

stirrer Remi stirrer, Mumbai, India.

Cyclomixer Remi Instruments, Mumbai,

India.

Multifuge Centrifuger Heraus,Germany.

109

6.2 ANALYTICAL METHODS

There are several reported methods for the estimation of

Citicoline available in the literature; those are UV, Colorimetry, HPLC

&LC-MS methods.

In the present investigation we have develop a modified

Ultraviolet spectroscopic method for the estimation of citicoline for

dissolution samples*.HPLC method was developed for estimation of

drug content (Assay)*.The analytical methods (i.e dissolution and

assay)of citicoline controlled release tablets not published in official

pharmacopeia.(i.e IP,BP&USP)

* The methods was developed on the basis of development and

validation of spectrophotometric determination of citicoline by Sanjay

Surani, V et al.,58 for dissolution samples and HPLC method for the

determination of citicoline by K.Tulasi, et al.,56 for assay samples.

A modified high pressure liquid chromatographic method was

developed and validated for the quantification of uridine in rabbit

plasma by Keguang Chen et al.,59.

6.2.1 Method Development

The solubility of the Citicoline was tested in different dissolution

medias like 0.1N HCl, pH 4.5 Acetate buffer, pH 6.8 phosphate buffers

and purified water. Based on the solubility data dissolution media pH

6.8 phosphate buffers was selected as media with 900mL of volume,

maintained at 37 ± 0.5°C.Study was conducted for selection of

dissolution apparatus (Basket or Paddle) with stirring rate (75 rpm

and 100 rpm) and found USP Apparatus-I (Basket) with 100 rpm is

110

suitable for this formulation. Samples were collected at appropriate

time intervals from dissolution vessels and diluted the samples and

measured the absorbance at 270nm using UV-Visible

spectrophotometer (Analytikjena Specord 210,) and calculated using

standard calibration curve.

6.2.1.1 Standard calibration curve of Citicoline

6.2.1.1.1 Preparation of pH 6.8 Phosphate buffer

Dissolve about 6.8gm of Potassium dihydrogen phosphate in

1000 mL of water. Adjust pH to 6.8 ± 0.05 with dilute sodium

hydroxide.

6.2.1.1.2 Preparation of standard stock solution

65.3 mg of Citicoline monosodium (equivalent to 62.5mg of

Citicoline) weighed in to 50mL volumetric flask and made up the

volume with pH 6.8 Phosphate buffer. 2mL of this solution further

diluted to 50mL with pH 6.8 Phosphate buffer. Filtered the solution

through 0.45µ nylon filter.

6.2.1.1.3 Preparation of Standard Calibration Curve

From the standard stock solution serial dilution were done to

obtain solutions ranging from 5.0µg/mL to 60µg/mL, i.e. from 10% to

120% with respect to sample concentration. The absorbance of above

solutions was measured at wavelength of 270nm using UV-Visible

spectrophotometer (Analytik jena), against dissolution media as blank.

The absorbance values of standard curve was represented in table

6.3and a graph was plotted of concentration v/s absorbance which

was shown in Fig. 6.1

111

Table 6.3: Calibration curve values

The linear equation was y = 0.0139, x = 0.0006

Where x is concentration and y is the peak absolute area.

The correlation coefficient was r2 = 1.000, indicating good linearity.

Figure 6.1: Standard Claibration Curve of Citicoline

y = 0.0139 x 0.0006 R² = 1.000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 10 20 30 40 50 60 70

Ab

sorb

ance

Concentration (µg/mL)

Concentration in µg/mL Absorbance

5 0.0704

10 0.1452

20 0.2699

30 0.4193

50 0.7028

60 0.8329

Slope 0.0139

Intercept 0.0006

Correlation Coefficient 1.000

112

6.2.2 Assay by HPLC

6.2.2.1 Method development

Different columns, mobile phases, flow and column

temperatures were tested in the development of the analytical method.

C-8 and C-18 columns of the same length, different lengths and

diameters were also tested and pH of buffer variations from 4.0 to 6.5

were also tested by keeping all parameters and conditions were

constant (0.8 mL/min., injection volume of 20µL, temperature at

25°C). Then the mobile phases with different buffer concentrations

and organic content were also tested by keeping the all parameters

and conditions were constant. Finally we got the good

chromatographic peak with more than 5000 theoretical plates, tailing

factor of less than 2.0 and Relative standard deviation of less than

2.0% for six replicate standard injections.

6.2.2.1.1 Preparation of dilute acetic acid

12.0 mL of acetic acid was diluted to 100mL with purified water.

6.2.2.1.2 Preparation of Buffer

1.697g of Tetra butyl ammonium hydrogen sulphate was

dissolved in 100 mL of purified water; 2mL of Triethyl amine added

and adjusted the pH to 6.0 with diluted acetic acid.

6.2.2.1.3 Preparation of mobile phase

Prepared and degassed mixture of buffer and acetonitrile in the

ratio of 75:25%v/v.

Diluent: Mobile phase used as diluent

113

6.2.2.1.4 Chromatographic conditions

Column : C18, 250×4.6mm 5µ or equivalent

Flow rate : 0.8mL/min

Detection : 270nm

Injection volume : 20µL

Column Temperature : 25°C

Run time : 10min

6.2.2.1.5 Standard preparation

52.25mg of Citicoline sodium (equivalent to 50mg of Citicoline)

weighed accurately in to 100 ml volumetric flask, dissolved and made

up the volume with 100mL with diluent. 5mL of this solution was

diluted to 50mL of diluent and mixed well.

6.2.2.2 Method validation76

The system suitability linearity, accuracy and precision of the

method were validated.

The specificity of test method by HPLC was demonstrated that

the excipients from tablets do not interfere with the analytic peak. The

linearity of the method was tested in the concentration range

5.04µg/mL to 60.48µg/mL (10.0% to 120.0%).For accuracy of the

method, standard drug was spiked from 70% to 130.0% and recovery

was found to be 99.3% to 100.3% and RSD 0.5%. The precision of the

method was checked were found to be relative standard deviation

1.1%.

114

Table 6.4: Linearity

Figure 6.2: Citicoline Assay Linearity graph

Table 6.5: Accuracy/recovery

Level Actual weight of

Citicoline added in mg % in mg recovery

% recovery

70% 35.30 35.4 100.3

100% 50.20 50.0 99.7

130% 65.10 64.6 99.3

Mean 99.7

SD 0.50

%RSD 0.50

y = 25434 x -16967.4 R² = 1.000

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000

0 10 20 30 40 50 60 70

Ab

sorb

ance

Concentration (µg/mL)

Concentration in µg/mL Peak Area

5.05 126981

10.1 250963

20.2 513926

30.3 754889

50.5 1259816

60.6 1532579

Slope 25434.0

Intercept -6967.4

Correlation Coefficient 1.000

115

Table 6.6: Precision

S.No. % Assay

1 100.9

2 99.1

3 99.8

4 101.0

5 98.2

6 99.2

Average 99.7

SD 1.10

% RSD 1.1

Figure 6.3: Citicoline Assay Standard

6.3 PRE-FORMULATION

6.3.1 Solubility Analysis

The solubility of Citicoline was determined in different media as

follows.

1. 0.1N HCl,

2. pH 4.5 Acetate buffer

3. pH 6.8 phosphate buffer

4. Purified water

116

1.0gm of Citicoline was weighed and transferred to separate 100

mL volumetric flasks. To each of the volumetric flasks above

mentioned media were added and shaken well. The volume was made

up to volume with same media the samples were kept in constant

water bath shaker for 24 hours at temperature of 37 °C. After 24

hours the samples were removed from bath, equilibrated for 1 hr. then

the samples were filtered through 0.45 μm filter.

The dissolved citicoline was measured using UV-Visible

spectrophotometer at 270 nm after suitable dilutions.

6.3.2 Compatibility Studies

6.3.2.1 Differential Scanning Calorimetry

Compatibility study of Citicoline with polymers was checked by

Differential Scanning Calorimetry at a heating rate 20°C/min over a

temperature range of 25-400°C under nitrogen flow of 25 mL min-1 for

maintaining inert atmospheres. The sample was hermetically sealed in

an aluminium crucible. Compatibility of the both materials will be

identified by observing any changes occur in melting points of the

drug.

6.3.2.2 Fourier Transform Infra-Red (FT-IR) spectral analysis

Compatibility of Citicoline with polymers was checked by

Fourier–Transformed Infrared (FT–IR) spectrums. spectrums were

taken individually and in combinations at range of 400 to 4000 cm-1

and the resolution was 1 cm-1 using Perkin Elmer, spectrum-100,

Japan with the KBr disk method (2 mg sample in 200 mg KBr).

117

6.4 PREPARATION OF MATRIX TABLETS

6.4.1 Preparation of matrix tablets containing Citicoline

The matrix tablets were prepared by wet granulation method by

using non-aqueous solvent. The composition of the tablet

formulations studies are represented in the Table 6.7.the procedure

as follows,

Step-1: The required amount of drug, polymers and diluents were

mixed in a SS container.

Step-2: Polymer was added to require amount of acetone under

continues stirring till dissolve or suspended.

Step-3: Step-1 material granulated using step-2 binder solution by

mixing thoroughly till wet mass forms and the wet mass was passed

through 14# mesh to obtain wet granules.

Step-4: The wet granules were transferred into a tray and dried in

hot air oven at 60 ± 5°C as inlet temperature until the LOD reaches

below 3.0 %.

Step-5: The dried granules were sifted through 20# mesh.

Step-6: The dried granules were mixed with colloidal silicone dioxide

(previously sifted through 40# mesh) and Magnesium stearate

(previously sifted through 60# mesh) for 5 min.

Step-7: Lubricated granules were compressed into tablets on

compression machine by using 22 x 10 mm oval shape punch for the

tablet size of 1580mg and 20 x 10 mm oval shape punch for the

tablet size of 1280 to 1420 mg.

118

Step-8: Preparation of coating solution

Eudragit RLPO was weighed, passed through 40# mesh and

dispersed into required amount of acetone and isopropyl alcohol (1:1)

mixture under continuous stirring. Talc and titanium dioxide was

weighed, mixed in mortar and festal, sifted through 80# mesh and

added to above mixture under stirring. Triacetin was weighed and

added to above solution under stirring. The solution was stirred for

45 minutes after addition of all ingredients.

Step-9: Tablets were coated using above prepared coating solution

using Conventional coating pan at drying temperature 55°C.

119

Table 6.7: Composition of matrix tablet containing Citicoline

S.No

Ingredients

mg/tablet

CTC/01 CTC/02 CTC/03 CTC/04 CTC/05 CTC/06 CTC/07 CTC/08 CTC/09 CTC/10 CTC/11 CTC/12 CTC/13 CTC/14 CTC/15 CTC/16

1 Citicoline Sodium

1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00 1045.00

2 MCC Avicel PH101

102.00 42.00 42.00 52.00 102.00 42.00 42.00 52.00 102.00 42.00 42.00 52.00 102.00 42.00 42.00 52.00

3 HPMC K 100 M 100.00 160.00 300.00 450.00 --- --- --- --- --- --- --- --- --- --- --- ---

4 HPC HF --- --- --- --- 100.00 160.00 300.00 450.00 --- --- --- --- --- --- --- ---

5 Eudrogit RLPO --- --- --- --- --- --- --- --- 100.00 160.00 300.00 450.00 --- --- --- ---

6 Eudrogit RSPO --- --- --- --- --- --- --- --- --- --- --- --- 100.00 160.00 300.00 450.00

7 Acetone QS QS QS QS QS QS QS QS QS QS QS QS QS QS QS QS

8 CSD 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00 15.00

9 Magnesium Stearate

18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00 18.00

Tablet Weight (Core) 1280.0 1280.0 1420.0 1580.0 1280.0 1280.0 1420.0 1580.0 1280.0 1280.0 1420.0 1580.0 1280.00 1280.0 1420.0 1580.0

10 Eudragit RLPO 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25 12.25

11 Talc 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10 5.10

12 Titanium Dioxide 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50

13 Triacetin 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15 1.15

14 Acetone : Isopropyl Alcohol (50:50 %)

QS QS QS QS QS QS QS QS QS QS QS QS QS QS QS QS

Tablet Weight (Coated) 1300.00 1300.00 1440.0 1600.0 1300.00 1300.0 1440.00 1600.0 1300.00 1300.0 1440.00 1600.0 1300.00 1300.0 1440.00 1600.0

MCC-Microcrystalline Cellulose, HPMC- Hydroxypropyl Methylcellulose, HPC- Hydroxypropyl cellulose, CSD-

Colloidal silicone dioxide

120

6.5 EVALUATION OF TABLETS

6.5.1 Evaluation of physical parameters for granules

6.5.1.1 Flowability78,79

Flowablility of lubricated granule were tested by using Bulk

density, Tap density, Compressibility, Hausner’s ratio and Angle of

repose.

The bulk density of prepared granules were determined by three-tap

method. Weighed quantity (15gm of granules) was carefully introduced

in to a 100mL graduated cylinder. The cylinder was dropped on to a

hard wood surface 3 times from a height of 2.5cm at an interval of

2sec. The bulk density was obtained by dividing weight of the sample

by volume of the sample.

The tap density is the ratio of weigth of the dry its tapped

volume. The above weighed quantity of granules was placed on tapped

density tester (Electrolab Model:ETD-1020) and subjected to USP –

Type II method i.e, 250 drops per minute and drop height is 3 mm ±

10%. The volume of the powdered weight is measured after increment

of 250 drops until the difference of last two values mean is zero.

Bulk Density =

Tapped Density =

Compressibility Index (%) and Hausner’s Ratio Can calculated by

using the following formulas.

=

×100

Hausner’s Ratio =

121

Angle of Repose

Take funnel stand with smooth base, keep the funnel and

adjust the funnel height such a way that the distance between the

powder pile and funnel should be approximately 2-4 cm. keep the

graph on base, hold the funnel orifice, pore powder and leave the

orifice to fall. Find the height (H) of the cone of powder and circle of

the powder carefully. Find out the angle of repose using following

equation:

"

Where, α is angle of the repose.

“H” is height of the powder cone

“R” is radius of the circle.

Table 6.8: Scale of flowability79

Flow Property Compressibility

Index

Hausner

Ratio

Angle of

Repose

Excellent ≤ 10 1.00-1.11 25-30

Good 11-15 1.12-1.18 31-35

Fair 16-20 1.19-1.25 36-40

Passable 21-25 1.26-1.34 41-45

Poor 26-31 1.35-1.45 46-55

Very poor 32-37 1.46-1.59 56-65

Very, Very

poor

>38 >1.60 >66

6.5.2 Evaluation of physical parameters for Tablets

6.5.2.1 Uniformity of Weight80

Ten tablets were selected randomly from each batch and

weighed individually and determine the average weight, then check for

122

weight variation. The average weight of tablet with % deviation as per

Indian pharmacopeia was represented in table

Table 6.9: Average weight of tablet with % deviation as per Indian

Pharmacopeia.

Average weight of Tablet % Deviation

80 mg or less 10

< 80 mg and < 250 mg 7.5

< 250 mg 5.0

6.5.2.2 Thickness

Thickness of the tablets was checked using digital Vernier

Caliper by placing the tablet in between the two jaws.

6.5.2.3 Hardness81

Hardness is main criteria for tablets and should have enough to

withstand mechanical stress like coating, packaging, shipment and

handling by the consumer. The crushing strength test of tablet

diametrically was performed on 10 tablets from each formulation by

using Dr.Schleuniger Hardness tester.

6.5.2.4 Friability82

The friability testis to evaluate the ability of the tablet to

withstand abrasion in coating, packaging, handling and shipping.

Friability of each formulation tested using 10tablets was

determined using a Roche type friability tester. 10 tablets were

weighed, transferred to friabilator and performed the test with 100 at

speed of 25 rpm. After completion of rotations tablets were removed,

123

dedusted and weighed. Friability of tablet should not be more than

1.0%.

Friability percentage was calculated using the following equation:

× 100

6.5.3 Drug content by HPLC

20 tablets were weighed accurately and determined average

tablet weight in mg. Tablets were crushed into fine powder. Powder

weighed equivalents to 50 mg of Citicoline in to 100mL volumetric

flask, add 60 mL of diluent and sonicated for 10 min. to dissolve.

Cooled the solution to room temperature and made up the

volume with diluent. 5 mL of the above solution was diluted to 50 mL

volumetric flask, made up the volume with diluent and mixed well.

Solution was filtered through 0.45µm nylon filter. Citicoline was

estimated by HPLC using developed method step: 6.2.2.

6.5.4 In-vitro Dissolution Study: by UV

In-vitro drug release studies were carried out using below parameters

Apparatus : USP- I (Basket)

Medium : Phosphate Buffer pH 6.8

Volume (mL) : 900

Revolutions (RPM) : 100

Temperature (°C) : 37±0.5

Specified Time (Hours) : 1, 3, 6, 9 and 12

124

6.5.4.1 Test Solution

900mL of dissolution medium was filled in to each of the six

dissolution vessels. One tablet in to each dissolution vessel

transferred and started the dissolution test. 10ml of aliquots was

withdrawn at regular interval and replaced with equal volume of fresh

dissolution medium to maintain the volume constant. Solution was

filtered through 0.45µ nylon. First 3mL of the filtrate was discarded,

diluted and analysed for drug content. The amount of drug released

was determined by UV at 270 nm.

6.5.4.2 Statistical approach to difference and similar factor83

Statistical models such as Difference factor (f1) and similar

factor (f2) both were constructed for optimised batch and marketed

product dissolution profile by using following equations.

Difference Factor f1={[∑t=1n (Rt-Tt)]/[ ∑t=1

n Rt]} x 100

Similar Factor f2=50 x log{[1+(1/n)∑t=1n (Rt-Tt)2]-0.5 x 100

Where,

n is number of time points.

R(t) is the mean % drug dissolved of reference product at time t.

T(t) is the mean % drug dissolved of test product.

f1 value should be close to 0 (0 to 15) to prove the both the

formulations are not different.

f2 value should be between 50 to 100 to prove the both the

formulations are similar.

125

6.5.5 Kinetic modeling system for In-vitro release84

6.5.5.1 Zero Order

Drug dissolution from dosage forms that do not disaggregate

and release the drug slowly (a constant release rate) can be

represented by zero order equation. To study the release kinetics, in

vitro data of drug release studies were plotted as cumulative amount

of percentage drug released versus time. It describes the rate of drug

release is independent of the concentration of dissolved substance.

C = Kot

Where, Ko is zero-order rate constant expressed in units of

concentration/time and t is the time.

Application: This equation can be used to describe the drug

dissolution of matrix tablets with low soluble drugs, osmotic systems

and transdermal systems,

6.5.5.2 First Order

This model useful in the determination of drug absorption

and/or elimination.Drug release depending on the concentration.

Log C=Log Co-kt /2.303

Where, Co = The initial concentration of drug and K is first order

constant.

Application: This equation can be used to describe the drug release in

porous matrices those containing water-soluble drugs.

6.5.5.3 Erosion model85

This equation defines the drug release based on erosion alone.

Q = 1-(1-k3t) 3

126

Where, Q is the fraction of drug released at time t, k3 is the release

rate constant. Thus, a plot between [1-(1-Q) 1/3] against time will be

linear if the release obeys erosion equation.

6.5.5.4 Korsmeyer-Peppas model

To find the drug release mechanism first 60% drug release data

were fitted in Korsmeyer-Peppas model, which described drug release

from a polymeric system equation. To study release kinetics, in vitro

drug release data was plotted as log cumulative % drug release versus

log time.

Mt / M∞= Ktn

Where Mt / M∞ = a fraction of drug released at time t,

K = The release rate constant and n is the release exponent. The n

value is used to characterize different mechanism of drug release for

cylindrical shaped matrices.

6.5.5.5 Higuchi’s Model

The first mathematical model which describes drug release from

a matrix system proposed by Higuchi in 1961. It is applicable for

planar systems initially; it was then extended to different geometrics

and porous systems.

Q=KH x T1/2

KH = The Higuchi dissolution constant

The values of cumulative percentage drug release versus square root

of time.

Application: This can be used to describe the drug release from matrix

tablets with water soluble drugs and transdermal systems.

127

6.6 STABILITY STUDIES86

Stability study of selected formulation was tested according to

international conference of harmonization guidelines. The tablets was

stored in Alu-Alu blister for 3 months in stability chamber at 40°C±

2°C&75% ± 5 % RH. Stability samples were tested for Physical, drug

content and in vitro dissolution.

128

6.7 RESULTS

6.7.1 Solubility Analysis

Table 6.10: Solubility of Citicoline in different media at

37 °C ± 0.5 °C.

Medium Solubility(mg/mL)

0.1N HCl 100

pH 4.5 Acetate buffer 100

pH 6.8 Phosphate buffer 100

Purified Water 100

Figure 6.4: Solubility Study of Citicoline in Different Media

0

20

40

60

80

100

120

0.1N HCl pH 4.5

Acetate buffer

pH 6.8

Phosphate

buffer

Purified Water

mg

/mL

Media

Solubility mg/ml

129

6.7.2 Compatibility Studies

6.7.2.1 Differential Scanning calorimetry

100.00 200.00 300.00Temp [C]

-40.00

-20.00

0.00

20.00

40.00

mWDSC

122.52 x100COnset

132.46 x100CEndset

126.86 x100CPeak

-1.29 x100J

-322.55 x100J/g

Heat

264.92 x100COnset

271.63 x100CEndset

272.41 x100CPeak

1.62 x100J

403.97 x100J/g

Heat

Citocolin Sodium

Figure 6.5: DSC of Citicoline

100.00 200.00 300.00 400.00Temp [C]

-0.00

10.00

mWDSC

257.63 x100COnset

270.34 x100CEndset

266.28 x100CPeak

782.54 x100mJ

195.63 x100J/g

Heat

123.32 x100COnset

151.28 x100CEndset

134.17 x100CPeak

-534.36 x100mJ

-133.59 x100J/g

Heat

Citicoline +HPMCK100M

Figure 6.6: DSC of Citicoline with HPMC K100M

130

100.00 200.00 300.00Temp [C]

-5.00

0.00

5.00

mWDSC

128.50x100COnset

153.77x100CEndset

143.19x100CPeak

-937.58x100mJ

-234.40x100J/g

Heat

255.83x100COnset

271.06x100CEndset

261.13x100CPeak

452.35x100mJ

113.09x100J/g

Heat

Citicoline + HPC

Figure 6.7: DSC of Citicoline with Hydroxypropyl Cellulose HF

100.00 200.00 300.00Temp [C]

-10.00

0.00

10.00

mWDSC

125.43 x100COnset

151.81 x100CEndset

144.28 x100CPeak

-620.56 x100mJ

-155.14 x100J/g

Heat

256.50x100COnset

268.95x100CEndset

263.76x100CPeak

696.28x100mJ

174.07x100J/g

Heat

Citicoline + Eudragit RLPO

Figure 6.8: DSC of Citicoline with Eudragit RLPO

131

100.00 200.00 300.00Temp [C]

-6.00

-4.00

-2.00

0.00

mWDSC

116.79x100COnset

142.37x100CEndset

133.20x100CPeak

-898.67x100mJ

-224.67x100J/g

Heat

251.85x100COnset

265.06x100CEndset

257.73x100CPeak

226.92x100mJ

56.73x100J/g

Heat

Citicoline + Eudragit RSPO

Figure 6.9: DSC of Citicoline with Eudragit RSPO

Table 6.11: DSC characteristics of pure drug and Combination

with Polymers

Parameters Citicoline

Sodium(API)

API+HPM

C K100M

API+HPC

HF

API+Eudragit

RLPO

API+Eudragit

RSPO

On Set (°C) 264.92 257.63 255.83 256.50 251.85

Peak (°C) 272.41 266.28 261.13 263.76 257.73

Area (mJ) 1620.00 782.54 452.35 696.28 226.92

Delta H (J/g) 403.97 195.63 113.09 174.07 56.73

132

6.7.2.2 Fourier Transform Infra-Red (FT-IR) spectral analysis

Figure 6.10: FTIR spectrum of Citicoline

Figure 6.11: FTIR spectrum of HPMC K100M

133

Figure 6.12: FTIR spectrum of Hydroxypropyl Cellulose HF

Figure 6.13: FTIR spectrum of Eudragit RLPO

134

Figure 6.14: FTIR spectrum of Eudragit RSPO

Figure 6.15: FTIR Spectrum of Citicoline with HPMC K100M

135

Figure 6.16: FTIR Spectrum of Citicoline with HPC HF

Figure 6.17: FTIR Spectrum of Citicoline with Eudragit RLPO

136

Figure 6.18: FTIR Spectrum of Citicoline with Eudragit RSPO

Table 6.12: Characteristic peaks of Citicoline

Frequency (cm-1) Functional Group

1651 C=O stretching in pyrimidine ring

3500 1° NH2 stretching in pyrimidine ring

1247 C-N stretching in pyrimidine ring

1081 C-O stretching in tetrahydro furan ring

981 C-C stretching in tetrahydro furan ring

Table 6.13: Characteristic peaks of HPMC K100M

Frequency (cm-1) Functional Group

1039 C-C stretching

2923 C-H stretching

1279 C-O stretching

3500 CH2CH(OH) CH3 Stretching value – OH

stretching

137

Table 6.14: Characteristic peaks of HPC HF

Frequency (cm-1) Functional Group

1089 C-C stretching

2924 C-H stretching

1262 C-O stretching

3500 CH2CH(OH) CH3 Stretching value – OH

stretching

Table 6.15: Characteristic peaks of Eudragit RLPO

Frequency (cm-1) Functional Group

1262 C-C stretching

2925 C-H stretching

1020 C-O stretching

1734 C=O stretching

Table 6.16: Characteristic peaks of Eudragit RSPO

Frequency (cm-1) Functional Group

1262 C-C stretching

2925 C-H stretching

1020 C-O stretching

1734 C=O stretching

Table 6.17: Characteric peaks of Citicoline + HPMC K100M

Frequency (cm-1) Functional Group

Citicoline

1651 C=O stretching

3500 -NH2 stretching in pyrimidine ring

HPMC K100 M

1081 C-C stretching

2924 C-H stretching

1243 C-O stretching

3500 CH2CH(OH) CH3 Stretching value – OH

stretching

138

Table 6.18: Characteristic peaks of Citicoline + HPC HF

Frequency (cm-1) Functional Group

Citicoline

1651 C=O stretching

3500 -NH2 stretching in pyrimidine ring

HPC HF

1081 C-C stretching

2924 C-H stretching

1243 C-O stretching

Table 6.19: Characteric peaks of Citicoline + Eudragit RLPO

Frequency (cm-1) Functional Group

Citicoline

1651 C=O stretching

3500 -NH2 stretching in pyrmidine ring

Eudragit RLPO

1082 C=O stretching

Table 6.20: Characteristic peaks of Citicoline + Eudragit RSPO

Frequency (cm-1) Functional Group

Citicoline

1655 C=O stretching

3500 -NH2 stretching in pyrmidine ring

Eudragit RSPO

1741 C=O stretching

1017 C-O stretching

2953 C-H stretching

1245 C-C stretching

139

6.7.3 Evaluation of Matrix Tablets

The tablets were evaluated for physical and chemical parameters.

6.7.3.1 Evaluation of physical parameters for granules

Table 6.21: Flowability

B.No.

Parameter

Bulk density

(gm/ml)

Tap density

(gm/ml)

Corr’s index

(%)

Hausners

ratio

Angle of

Repose(°)

CTC/01 0.435 0.607 28.3 1.39 48.2

CTC/02 0.327 0.422 22.5 1.29 43.5

CTC/03 0.347 0.448 22.5 1.29 42.8

CTC/04 0.366 0.578 36.6 1.57 56.5

CTC/05 0.380 0.500 24.0 1.31 43.2

CTC/06 0.318 0.406 21.7 1.28 42.3

CTC/07 0.348 0.429 18.9 1.23 36.4

CTC/08 0.366 0.440 16.8 1.202 37.1

CTC/09 0.348 0.445 21.79 1.27 42.8

CTC/10 0.487 0.634 23.2 1.30 41.9

CTC/11 0.568 0.679 16.3 1.20 36.7

CTC/12 0.458 0.589 22.24 1.28 42.7

CTC/13 0.361 0.425 15.05 1.17 36.4

CTC/14 0.495 0.625 20.8 1.26 37.2

CTC/15 0.521 0.659 21.1 1.27 41.4

CTC/16 0.500 0.571 12.4 1.14 31.6

140

6.7.3.2 Evaluation of physical parameters for Tablets

Table 6.22: Physical parameters of Core Tablets

B. No.

Parameters

Wt. of

individual

tablets(mg)

Hardness

(kp)

Thickness

(mm)

Friability

(%w/w)

CTC/01 1245-1315 36.7-39.8 6.75 - 6.83 0.14

CTC/02 1252-1313 38.7-40.7 6.74 - 6.82 0.21

CTC/03 1382-1440 37.0-40.0 6.82 - 6.93 0.19

CTC/04 1535-1625 35.2-40.5 6.86 - 6.94 0.15

CTC/05 1248-1314 35.4-40.9 6.73 - 6.81 0.13

CTC/06 1250-1310 36.2-41.0 6.74 - 6.81 0.1

CTC/07 1385-1442 35.6-41.3 6.81 - 6.92 0.1

CTC/08 1538-1623 36.6-39.4 6.85 - 6.94 0.1

CTC/09 1247-1313 36.5-39.3 6.71 - 6.84 0.14

CTC/10 1245-1316 37.7-39.5 6.72 - 6.80 0.21

CTC/11 1390-1437 37.2-39.7 6.81 - 6.94 0.19

CTC/12 1537-1627 35.5-40.3 6.87 - 6.94 0.15

CTC/13 1243-1310 35.0-37.9 6.72 - 6.80 0.14

CTC/14 1244-1314 35.1-38.4 6.74 - 6.82 0.16

CTC/15 1389-1438 34.9-38.0 6.82 - 6.94 0.12

CTC/16 1539-1623 34.7-39.4 6.85 - 6.93 0.11

141

Table 6.23: Physical evaluation of Coated tablets

B.No

Parameters

Wt. of

individual

tablets (mg)

Hardness

(kp)

Thickness

(mm)

CTC/01 1264-1336 36.7-39.8 6.78 - 6.85

CTC/02 1273-1334 38.7-40.7 6.73 - 6.84

CTC/03 1401-1461 37.0-40.0 6.85 - 6.95

CTC/04 1554-1663 35.2-40.5 6.89 - 6.97

CTC/05 1267-1336 35.4-40.9 6.77 - 6.84

CTC/06 1271-1332 36.2-41.0 6.78 - 6.84

CTC/07 1406-1461 35.6-41.3 6.85- 6.93

CTC/08 1559-1645 36.6-39.4 6.89 - 6.96

CTC/09 1266-1335 36.5-39.3 6.76 - 6.85

CTC/10 1266-1337 37.7-39.5 6.77 - 6.83

CTC/11 1411-1458 37.2-39.7 6.85 - 6.97

CTC/12 1556-1648 35.5-40.3 6.92 - 6.97

CTC/13 1264-1331 35.0-37.9 6.77 - 6.83

CTC/14 1263-1336 35.1-38.4 6.78 - 6.83

CTC/15 1410-1459 34.9-38.0 6.86 - 6.96

CTC/16 1560-1642 34.7-39.4 6.89 - 6.96

142

Figure 20: Photograph of prepared citicoline controlled release

Tablets (B. No: CTC/14)

6.7.3.3 Evaluation of Chemical parameters for Tablets

6.7.3.3.1 Drugu Content

Table 6.24: Drug Content

Parameter

BATCH NO

CTC/

01

CTC/

02

CTC/

03

CTC/

04

CTC/

05

CTC/

06

CTC/

07

CTC/

08

Drug

content (%)

99.6 99.9 99.6 99.1 99.5 99.2 99.8 99.6

CTC/

09

CTC/

10

CTC/

11

CTC/

12

CTC/

13

CTC/

14

CTC/

15

CTC/

16

99.2 99.7 99.3 100.7 100.1 100.8 100.6 100.8

143

6.7.3.3.2 In-vitro Dissolution Study

Table 6.25: Dissolution Study

B. No Cumulative % Drug Release

1hr 3hr 6hr 9hr 12hr

CTC/01 64.1 85.6 98.6 99.7 100.2

CTC/02 60.2 80.5 98.3 99.0 99.1

CTC/03 57.0 75.5 95.8 99.0 99.4

CTC/04 33.7 80.6 95.5 98.9 99.8

CTC/05 66.6 93.3 99.0 99.6 99.8

CTC/06 65.5 87.1 99.1 99.2 99.3

CTC/07 59.6 80.6 96.6 99.0 99.0

CTC/08 44.4 74.6 90.6 97.5 99.4

CTC/09 62.7 82.8 98.2 98.8 98.8

CTC/10 59.8 79.1 96.0 99.1 99.2

CTC/11 56.6 75.1 93.2 99.0 99.0

CTC/12 50.3 72.8 89.9 96.6 98.2

CTC/13 44.9 56.7 76.2 95.3 99.1

CTC/14 30.1 47.2 58.8 80.4 99.7

CTC/15 31.9 47.9 56.6 82.0 99.2

CTC/16 34.1 45.3 63.6 84.0 99.7

Figure 6.21: In-vitro release of formulations containing HPMC K100M retardant

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13

% D

rug r

elea

se

Time in (hr.)

In-vitro release of formulations containg HPMC

K100M retardant

CTC/01

CTC/02

CTC/03

CTC/04

144

Figure 6.22: In-vitro release of formulations

containing HPC HF as retardant

Figure 6.23: In-vitro release of formulations containing Eudragit RLPO as retardant

Figure 6.24: In-vitro release of formulations containing Eudragit RSPO as retardant

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13

% D

rug r

elea

se

Time in (hr.)

In-vitro release of formulations containg HPC HF as

retardant

CTC/05

CTC/06

CTC/07

CTC/08

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13

% D

rug r

elea

se

Time in (hr.)

In-vitro release of formulations containg Eudragit RLPO

as retardant

CTC/09

CTC/10

CTC/11

CTC/12

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13

% D

rug

rel

ease

Time in (hr.)

In-vitro release of formulations containg Edragit RSPO as

retardant

CTC/13

CTC/14

CTC/15

CTC/16

145

Table 6.26: Compilation of Dissolution Profile of optimized batch

with Market product

Time points Marketed Product CTC/14

1 hour 32.0 30.1

3 hour 53.1 47.3

6 hour 64.5 58.8

9 hour 84.7 80.4

12 hour 98.4 99.7

F2 value 67.91

F1 value 4.96

Table 6.27: Citicoline f1& f2 values

S.No B. No. Dissimilarity

factor ( f1)

Similarity

factor(f2 )

1. CTC/13 11.87 51.53

2. CTC/14 4.96 67.91

3. CTC/15 4.54 67.22

4. CTC/16 1.80 70.86

Figure 6.25: Comparison of in-vitro release of CTC/14 Marketed Product

0

20

40

60

80

100

120

0 1 2 3 4 5 6 7 8 9 10 11 12 13

% D

rug r

elea

se

Time (hr.)

Comparation of invitro release of CTC/14 with Marketed

Product

Marketed Product

CTC/014

146

6.7.4 Kinetic modelling system for In-Vitro release

Table 6.28: In vitro release kinetics of Citicoline controlled

release tablets.

B.NO Correlation Coefficient (r2)

k (h-1) n

value Zero First Higuchi Erosion Peppas

STROLIN -OD 0.9902 0.9239 0.9932 0.9716 0.9942 0.3123 2.2467

CTC/01 0.8477 0.9956 0.9201 0.9896 0.9651 0.6203 5.0133

CTC/02 0.8590 0.9300 0.9272 0.9090 0.9693 0.3729 4.4276

CTC/03 0.8949 0.9855 0.9514 0.9622 0.9810 0.4194 4.0296

CTC/04 0.8139 0.9992 0.8931 0.9603 0.9299 0.5162 1.9926

CTC/05 0.7623 0.9703 0.8507 0.9032 0.9183 0.4599 5.2315

CTC/06 0.8230 0.9005 0.9014 0.8838 0.9544 0.3715 5.2662

CTC/07 0.8696 0.9611 0.9358 0.9389 0.9738 0.3677 4.4224

CTC/08 0.8930 0.9976 0.9524 0.9885 0.9752 0.4073 2.8882

CTC/09 0.8498 0.9159 0.9211 0.8990 0.9663 0.3360 4.8515

CTC/10 0.8848 0.9727 0.9460 0.9531 0.9794 0.3910 4.4538

CTC/11 0.9097 0.9695 0.9621 0.9649 0.9867 0.3843 4.0712

CTC/12 0.9149 0.9969 0.9667 0.9818 0.9879 0.3111 3.4991

CTC/13 0.9807 0.9686 0.9893 0.9898 0.9842 0.3785 2.8740

CTC/14 0.9957 0.9732 0.9830 0.9313 0.9862 0.4337 2.0982

CTC/15 0.9915 0.8799 0.9744 0.9417 0.9751 0.3624 2.1650

CTC/16 0.9993 0.8707 0.9869 0.9482 0.9798 0.4382 2.2164

147

Figure 6.26: Zero order plots for B. No: CTC/14

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

Co

mu

lati

ve p

erce

nt

dru

g re

leas

e (

%)

Time (hr)

STROLIN -OD

CTC/14

Linear (STROLIN -OD)

Linear (CTC/14)

148

Figure 6.27: First order plots for B. No: CTC/14

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12 14

Log

per

cen

t re

mai

nin

g to

be

rele

ase

d

Time (hr)

STROLIN - OD

CTC/14

Linear (STROLIN - OD)

Linear (CTC/14)

149

Figure 6.28: Higuchi plots for B. No: CTC/14

0

20

40

60

80

100

120

0.000 0.500 1.000 1.500 2.000 2.500 3.000 3.500 4.000

Co

mu

lati

ve p

erc

en

t d

rug

rele

ase

(%

)

Square root time (hr)

STROLIN - OD

CTC/14

150

Figure 6.29: Erosion plots for B. No: CTC/14

0.000

0.200

0.400

0.600

0.800

1.000

1.200

0 2 4 6 8 10 12 14

(1-Q

)1/3

Time (hr)

STROLIN-OD

CTC/14

Linear (STROLIN-OD)

Linear (CTC/14)

151

Figure 6.30: Korsmeyer-Peppas plots for B. No: CTC/14

0.000

0.500

1.000

1.500

2.000

2.500

0 0.2 0.4 0.6 0.8 1 1.2

Log

frac

tio

n r

ele

ase

d

LogTime (hr)

Strocit

CTC/14

152

6.7.5 Stability Studies

Stability studies for Formulation B.No:CTC/14 revealed that

there was no significant change in appearance, assay, and drug

release profile at 40°C± 2°&75% RH till 3 months.

Table 6.29: Stability study values

Parameters Time period

Initial 1 Month 2 Month 3 Month

Description Complies Complies Complies Complies

Drug content (%) 100.8 100.5 100.3 100.2

Dis

solu

tion

1Hr 30.1 29.9 31.0 30.5

3Hr 47.3 46.9 47.1 47.8

6Hr 58.8 58.2 58.4 59.2

9Hr 80.4 80.8 79.9 81.4

12Hr 99.7 99.3 99.9 99.3

6.8 DISCUSSION

6.8.1 Solubility results shown in Table6.10

Solubility test reveals that the Citicoline sodium is soluble in pH range

of 1 to 7.0.

6.8.2 Compatibility Studies:

6.8.2.1 Differential Scanning Calorimeter (DSC) results are shown in

Table6.11.

The DSC thermograph for Citicoline showed melting peak starts

at 264.92°C ending at 272.41°C and the mixer of the Citicoline+

HPMC K 100M, Citicoline + HPC HF, Citicoline + Eudragit RLPO,

153

Citicoline + Eudragit RSPO showed melting points starting at

257.63°C, 255.83°C , 256.50°C & 251.85°C ending at 266.28°C ,

261.13°C, 263.76°C & 257.73°C respectively. The exothermic energy

of Citicoline was 403.97 J/g and the mixer of the Citicoline+ HPMC K

100M, Citicoline + HPC HF, Citicoline + Eudragit RLPO, Citicoline +

Eudragit RSPO were 195.63J/g , 113.09J/g, 174.07J/g & 56.73 J/g

respectively. From the obtained results concluded that there is no

interaction between the selected polymers and drug substance.

6.8.3 Fourier Transform Infra-Red (FT-IR) spectral results are shown

in Table6.12-6.20.

The FT-IR spectra of pure drug showed characteristic peaks at

1651 cm-1,3500 cm-1,1247 cm-1, 1081 cm-1,1213 cm-1, & 981 cm-1.

The mixer of drug substance and polymers of the selected in the

formulations also showed same characteristic peaks with linear and

shift so these values supported that there is no interaction between

the selected polymers and the drug substance.

6.8.4 The results of bulk properties are shown in Table 6.21.

The bulk density of the prepared formulations had in the range

of 0.318g/mL to 0.568g/mL.

The tapped density was found to be in the range of 0.406g/mL to

0.679g/mL.

The Carr’s index and Hausner’s ratio varies in the range of

12.4%, 1.14 to 36.6%, 1.57 respectively and the angle of repose was

found to be in the range of 31.6° to 56.5°. The bulk properties of B.No:

154

CTC/14 was showed flow properties.(20.80 %,1.260 and 37.20º

respectively).

The results clearly indicate that the prepared blends have fair

flowability and compressibility.

6.8.5 Results of core tablet uniformity of weight are shown in

Table6.22 all batches were found within specified range ±5.0% as per

Indian Pharmacopeia.

6.8.6 Core Tablet Thickness results are shown in Table6.22.

Thickness of tablet containing total weight 1280 mg was found

in the range of 6.71 to 6.84 mm. Thickness of tablet containing total

weight 1420 mg was found in the range of 6.81 to 6.94 mm. Thickness

of tablet containing total weight 1580 mg was found in the range of

6.85 to 6.94 mm. Thickness of all batch tablets was found satisfactory

with respect to punches and tablet weight.

6.8.7Core Tablet Hardness results are show in Table6.22.

Hardness of tablets having 1280 mg weight contains 35.0 to

41.0 kp, 1420 mg weight contains 34.9 to 41.3Kp and 1580 mg

weight contains 34.7 to 40.5 kp. Selected batch (B.No:CTC/14) found

with 35.1 to 38.4kp.

6.8.8 Friability results are show in Table6.22.

Friability of all tablets was found in the range of 0.10 - 0.21%

w/w, which found within the specified limit. Friability of selected

batch (B.No: CTC/14) was 0.16%.

155

6.8.9 Results of coated tablet uniformity of weight are shown

inTable6.23. All batches were found within specified range ±5.0% as

per Indian Pharmacopeia.

6.8.10Coated Tablet Thickness results are shown in Table 6.23.

Thickness of tablet containing total weight 1300 mg was found

in the range of 6.73 to 6.85 mm. Thickness of tablet containing total

weight 1420 mg was found in the range of 6.85 to 6.97 mm. Thickness

of tablet containing total weight 1600 mg was found in the range of

6.89to 6.97 mm. Thickness of all batch tablets was found satisfactory

with respect to punches and tablet weight.

6.8.11 CoatedTablet Hardness results are show in Table 6.23.

Hardness of tablets having 1300 mg weight contains 35.0 to

41.0 kp, 1420 mg weight contains 34.9 to 41.3Kp and 1600 mg weight

contains 34.7 to 40.5 kp. selected batch (B.No:CTC/14) found with

35.1 to 38.4kp.

6.8.12 The results of the assay shown in Table 6.24.

The assay results are found within the pharmacopeial limits

which indicate uniformity in drug content for all the prepared

formulations.

6.8.13 The results of Dissolution studies are shown in Table 6.25.

Those formulations containing HPMC K100 M (B.No: CTC/01,

CTC/02, CTC/03 & CTC/04) varies in the concentrations

7.8,12.5,21.12& 28.48% w/w per tablet respectively. Obtained

results are shows that the high amount of HPMC K 100 M is required

to retard the release rate and also increase the tablet size respectively

156

which is difficult to swallow the patient. Concentrations varies from

7.8, 12.5, 21.12 & 28.48 %w/w of HPC HF per tablet in the

formulations B.No: CTC/05, CTC/06, CTC/07& CTC/08 respectively.

Since it is not shown the better performance than HPMC K 100 M but

it is shown the similar results with HPMC K100M. Finally high

amount of HPC HF required controlling the release rate and also

increasing the tablet size respectively which is difficult to swallow.

Formulations containing Eudragit RLPO are unable to control

the initial release of the drug even at maximum concentration of 450

mg. More than 50% of the drug released in 1 hour. Hence Eudragit

RLPO is considered to be failed in the design of controlled release

Citicoline. The release of Citicoline from tablets containing Eudragit

RSPO was well controlled. The release is extended for about 12 hours.

The formulation showed satisfactory in-vitro results at concentration

of 160 mg/tablet. There is not much variation in controlling of drug

release with increasing the concentration of Eudragit RSPO such as

300 mg, 450 mg per tablet. The optimum concentration is found to be

160 mg for formulation B.No: CTC/14. For comparison of marketed

Citicoline controlled release tablets were also evaluated for

dissolution. Marketed tablets could extend the release of the drug for

about 12 hours. The release of the drug from marketed formulation

was compared with all the prepared formulations and calculated

similarity factor and difference factor. The values indicated formula

B.No: CTC/14 containing Eudragit RSPO is best formula among all.

157

6.8.14 The similarity and dissimilarity factor values are shown in

Table 6.27.

The f1, f2 are calculated by using the equation proposed by More

et al, the results of formulation (Batch no: CTC/14) f1= 4.96, f2= 67.91

So, it indicates the proposed formulation is similar to that of the

marketed formulation.

6.8.15The results of drug release kinetics are shown in Table 6.28.

The release profile was studied for kinetics of the drug release

by zero order and first order kinetics. The correlation coefficient value

(r2) of zero order and first order for all formulation were found to be in

the range of 0.7623 -0.9993 and 0.8707-0.9992. These results

indicate that the release follows first order kinetics.

The mechanism of drug release was studied by using Higuchi’s,

Erosion and Peppas model. The correlation r2 values found to be

(0.8507 – 0.9932), (0.8838 – 0.9898) and (0.9183 – 0.9942)

respectively, this results indicates the release mechanism follows with

super case II transport (as n value more than 1) . From the observed

results indicate the drug release follows first order kinetics with

diffusion mechanism.

6.8.16 The results of stability studies are shown in Table 6.29.

The stability studies were conducted on the selected formulation

(B.No: CTC /14) at 40°C/75% RH for 3 months. The tablet was

evaluated for Description, Assay and Dissolution.

There is no significance difference between the initial and final

exposed samples with required physical stability and chemical

158

stability like assay and dissolution. So this indicates the selected

formulation is stable.