Formulation Development and Evaluation of Clopidogrel Fast Dissolving Tablets

Iranian Journal of Pharmaceutical Sciences
2016: 12 (2): 61-74
www.ijps.ir
Original Article
Formulation Development and Evaluation of Clopidogrel Fast Dissolving
Tablets
Gunda Raghavendra Kumar *a
, J.N.Suresh Kumara
, V.Satyanarayanab
, G.Swarupa Ranic
, B.Satya Prasadd
a
Department of Pharmaceutics, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur
(Dt), Andhra Pradesh, India-522601.
b
Department of Pharmacy Practice, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur
c
Department of Pharmacology, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet, Guntur
d
Department of Pharmaceutical Analysis, Narasaraopeta Institute of Pharmaceutical Sciences, Narasaraopet,
Guntur (Dt), Andhra Pradesh, India-522601.
Abstract
The main objective of the present research work is to formulate the Clopidogrel Fast Dissolving tablets.
Clopidogrel, an antiplatelet drug, belongs to BCS Class-II and used to control Heart attack, Hypertension by
inhibiting Platelet activation and aggregation .The Fast Dissolving tablets of Clopidogrel were prepared
employing different concentrations of Crospovidone and Croscarmellose sodium in different combinations as a
Superdisintegrant by Direct Compression technique using 32
factorial design. The concentration of
Crospovidone and Croscarmellose sodium was selected as independent variables, X1 and X2 respectively
whereas, wetting time, Disintegration time, t50%, t90% were selected as dependent variables. Totally nine
formulations were designed and evaluated for hardness, friability, thickness, Assay, Wetting time,
Disintegration time, and in-vitro drug release. From the Results it was concluded that all the formulation were
found to be with in the Pharmacopoeial limits and the in-vitro dissolution profiles of all formulations were
fitted into different Kinetic models, the statistical parameters like intercept (a), slope (b) and regression
coefficient (r) were calculated. Polynomial equations were developed for Wetting time, Disintegration time,
t50%, t90%. Validity of developed polynomial equations was verified by designing 2 check point formulations (C1,
C2). According to SUPAC guidelines, the formulation (F5) containing combination of 15% Crospovidone and
15% Croscarmellose, is the most similar formulation (similarity factor f2=91.3936, dissimilarity factor f1=
1.203& No significant difference, t= -0.00062) to marketed product (PLAVIX-75). The selected formulation
(F1) follows First order, Higuchi’s kinetics, mechanism of drug release found to be Fickian Diffusion (n=
0.226).
Keywords : Clopidogrel, 32
Factorial Design, super disintegrants, Crospovidone , croscarmellose Sodium,
Wetting Time, Disintegration Time, Fickian Diffusion.

Kumar G R, et al / IJPS 2016; 12 (2): 61-74
62
1. Introduction
Researchers throughout the world are
focusing intensively on the methods for the
development of new drug delivery systems to
enhance patient’s compliance. Fast dissolving
tablets become an emerging trend in the
pharmaceutical industry. Fast dissolving
tablets are ideal for all types of people,
including for people who have swallowing
difficulties, pediatric, geriatric, and bedridden
patients. It is also for active patients who are
busy, travelling and may not have access to
water. Fast dissolving tablets are also known
as oro dispersible tablets, mouth-dissolving
tablets, orally disintegrating tablets, melt-in
mouth tablets, rapimelts, porous tablets, quick
dissolving, etc. Many drugs have the potentials
to be made into oro dispersible tablets. They
vary from analgesics to neuroleptics and anti-
psychotic drugs. However, only a small
percentage of them are researched on and
some have been manufactured and marketed.
Fast-dissolving drug-delivery systems were
initially developed in the late 1970s as an
alternative to tablets, capsules, and syrups for
pediatric and geriatric patients who
experiences difficulties in swallowing
traditional oral solid-dosage forms [1]. The
speed of solubility of drug affects the rate of
absorption of the drug. The faster the drug
dissolve into solution, quicker the absorption
and onset of clinical effect. They should
readily dissolve or disintegrate in the saliva
generally within <60 seconds. Some drugs are
absorbed from the mouth, pharynx, and
esophagus as the saliva passes down into the
stomach. The significance of oro dispersible
dosage forms are progressively being
recognized in both, industry, and academics
[2, 3].The small volume of saliva is usually
sufficient to result in tablet disintegration in
the oral cavity. The medication can then be
absorbed partially or entirely into the systemic
circulation from blood vessels in the
sublingual mucosa, or it can be swallowed as a
solution to be absorbed from the
gastrointestinal tract. The sublingual route
usually produces a faster onset of action than
orally ingested tablets and the portion
absorbed through the sublingual blood vessels
bypasses the hepatic first-pass metabolic
processes [4]. The performance of ODT
depends on the technology used in their
manufacture. The orally disintegrating
property of the tablet is attributable to a quick
intake of water into the tablet matrix, which
creates porous structures and result in rapid
disintegration. Hence, the basic approaches to
develop ODT include maximizing the porous
structure of the tablet matrix, incorporating the
appropriate disintegrating agent and using
highly water soluble excipients in the
formulation. Orally disintegrating tablets are
formulated by utilizing several processes,
which differ in their methodologies and the
Corresponding Author: Raghavendra Kumar Gunda,
Department of Pharmaceutics, Narasaraopeta Institute of
Pharmaceutical Sciences, Narasaraopet, Guntur (Dt), Andhra
Pradesh, India-522601.
Tel: +91-9666705894
E-Mail: raghav.gunda@gmail.com
Cite this article as: Kumar G R, Kumar J.N.S, Satyanarayana
V, Swarupa Rani G, Prasad B.S, Formulation Development
and Evaluation of Clopidogrel Fast Dissolving
Tablets.Iranian Journal of Pharmaceutical Sciences, 2016, 12
(2): 61-74.

Clopidogrel fast dissolving tablets
63
ODTs formed vary in various properties such
as, mechanical strength of tablet, taste and
mouth feel, swallowability, drug dissolution in
saliva, bioavailability and stability. Various
processes employed in formulating ODTs
include Freeze-Drying or Lyophilization,
cotton candy process, molding, spray drying,
mass extrusion, and compaction (wet
granulation, dry granulation, direct
compression) [5].
In the present study, the direct compression
method was adopted to manufacture the ODT
tablets, since it is very simple and do not
require any sophisticated equipment’s. The
direct compression represents the simplest and
most cost effective tablet manufacturing
technique.
ODT by direct compression technique is a
simple approach of drug delivery systems that
proved to be rational in the pharmaceutical
arena for its ease, compliance, faster
production, avoid hydrolytic, or oxidative
reactions occurred during processing of dosage
forms.
1.1. Drug Profile and Rationality for
Experimental Design
Clopidogrel, a weak base known
chemically as Methyl (S)- α- (2chlorophenyl)-
6,7-dihydrothieno[3,2-c]pyridine-5(4H)-
acetate sulfate (1:1)].It is practically insoluble
in water at neutral pH, freely soluble in
aqueous buffer at pH 1, and in methanol,
sparingly soluble in methylene chloride, and
practically insoluble in ethyl ether
[6].Clopidogrel is an inhibitor of platelet
activation and aggregation through the
irreversible binding of its active metabolite to
the P2Y12 class of ADP receptors on platelets.
The blockade of inhibits platelet aggregation
by blocking activation of the glycoprotein
IIb/IIIa pathway. Platelet inhibition can be
demonstrated 2 h after a single dose of oral
Clopidogrel, but the onset of action is slow( so
that a loading-dose of 300-mg is followed by
75 mg once daily).The active metabolite has
an elimination half-life of about six hours and
acts by forming a disulfide bridge with the
platelet ADP receptor [7-10].
According to the biopharmaceutics
classification system (BCS), Clopidogrel is
categorized as a class II agent (poorly water
soluble and highly permeable) its solubility is
very low (i.e., 0.0099 mg/ml) and has very low
bioavailability [6]. Oral bioavailability of
clopidogrel is very low (less than 50%), due to
poor water solubility.Hence, the drug is
selected for formulating Fast Dissolving
Tablets by Direct compression method.
It is an important issue is to design an
optimized formulation with an appropriate
dissolution rate in a short time period and
minimum trials. Many statistical experimental
designs have been recognized as useful
techniques to optimize the process variables.
For this purpose, response surface
methodology (RSM) utilizing a polynomial
equation has been widely used. Different types
of RSM designs include 3-level factorial
design, central composite design (CCD), Box-
Behnken design and D-optimal design.
Response surface methodology (RSM) is used
when only a few significant factors are
involved in experimental optimization. The

64
technique requires less experimentation and
time, thus proving to be far more effective and
cost-effective than the conventional methods
of formulating sustained release dosage forms
[11-14].
Hence an attempt is made in this research
work to formulate Fast Dissolving Tablets of
Clopidogrel using Crospovidone and
Croscarmellose sodium. Instead of normal and
trial method, a standard statistical tool design
of experiments is employed to study the effect
of formulation variables on the release
properties.
Large scale production needs more
simplicity in the formulation with economic
and cheapest dosage form. The Fast
Dissolving tablets formulation by direct
compression method is most acceptable in
large scale production.
A 32
full factorial design was employed to
systematically study the drug release profile.
A 32
full factorial design was employed to
investigate the effect of two independent
variables (factors), i.e the amounts of
Crospovidone and Croscarmellose on the
dependent variables, i.e. Disintegration time,
Wetting Time, t50%, t90%, (Time taken to
release 50%, 90% respectively)
2. Materials and Methods
Materials used in this study were obtained
from the different sources. Clopidogrel was a
gift sample from Dr.Reddy’s Laboratories,
Hyderabad, India. Avicel pH-101,
Crospovidone, Croscarmellose, were procured
from Loba ChemiePvt.Ltd, Mumbai. Other
excipients such as Magnesium Stearate and
talc were procured from S.D. Fine Chem. Ltd.,
Mumbai.
2.1. Formulation Development of Clopidogrel
Fast Dissolving Tablets
The factorial design is a technique that
allows identification of factors involved in a
process and assesses their relative importance.
In addition, any interaction between factors
chosen can be identified. Construction of a
factorial design involves the selection of
parameters and the choice of responses [15].
A selected three level, two factor
experimental design (32
factorial design)
describe the proportion in which the
independent variables Crospovidone and
Croscarmellose sodium were used in
formulation of Clopidogrel Fast Dissolving
Tablets. The time required for 50% (t50%),
90% (t90%) drug dissolution, Disintegration
Time and Wetting Time were selected as
dependent variables. Significance terms were
chosen at 95% confidence interval (p<0.05)
for Final Equations. Polynomial equations
were developed for t50%, t90%, Disintegration
Time and Wetting Time (step-wise backward
Linear Regression Analysis).
The three levels of factor X1
(Crospovidone) at a concentration of 7.5%,
10.0%, 15%,three levels of factor X2
(Croscarmellose) at a concentration of 7.5%,
10.0%, 15%. (% with respect to average
weight of Tablet, i.e200 mg) were taken as the
rationale for the design of the Clopidogrel Fast
Dissolving tablet formulation. Totally nine
Clopidogrel Fast Dissolving tablet
formulations were prepared employing

65
selected combinations of the two factors i.e,
X1, X2 as per 32
Factorial and evaluated to find
out the significance of combined effects of X1,
X2 to select the best combination and the
concentration required to achieve the desired
Fast release/ Dissolution of drug (by providing
large Surface area and Improved Solubility)
from the dosage form.
2.2. Preparation of Clopidogrel Fast
Dissolving Tablets
Clopidogrel Tablets were prepared by
direct compression method. The composition
of each tablet is shown in Table No 2. The
drug, diluents, and superdisitegrants were
passed through sieve #40. All the above
ingredients were properly mixed together (in a
poly-bag). Talc and Magnesium stearate were
passed through mesh #80, mixed and blended
with initial mixture in a poly-bag. The powder
blend was compressed into tablets on a 8
station rotary punch tableting machine
(minipress) using 8 mm circular punches and
same hardness was used for the required
number tablets. Compressed tablets were
examined as per official standards and
unofficial tests. Tablets were packaged in well
closed light resistance and moisture proof
containers.
2.2.1. Experimental Design
Experimental design utilized in present
investigation for the optimization of
Superdisintegrant concentration such as,
concentration of Crospovidone was taken as
X1 and concentration of Croscarmellose
sodium was taken as X2. Experimental design
was given in the Table 1. Three levels for the
Concentration of Crospovidone were selected
and coded as -1= 7.5%, 0=10.0%, +1=15%.
Three levels for the Concentration of
Croscarmellose sodium were selected and
coded as -1= 7.5%, 0=10.0%, +1=15%.
Formulae for all the experimental batches
were given in Table 2 [16].
2.3. Evaluation of Clopidogrel Fast Dissolving
Tablets
2.3.1. Hardness
The hardness of the tablets was tested by
diametric compression using a Monsanto
Hardness Tester. A tablet hardness of about 2-
4 Kg/cm2
is considered adequate for
mechanical stability [17].
2.3.2. Friability
The friability of the tablets was measured
in a Roche friabilator (Camp-bell Electronics,
Mumbai). 20 Tablets were taken and weighed,
and also initial weight was noted (W0)
Table 1. Experimental design layout.
Formulation Code X1 X2
F1 1 1
F2 1 0
F3 1 -1
F4 0 1
F5 0 0
F6 0 -1
F7 -1 1
F8 -1 0
F9 -1 -1
C1 -0.5 -0.5
C2 +0.5 +0.5

66
dedusted in a drum for a fixed time (100
revolutions, in a Roche Friabilator) and they
were weighed (W) again. Percentage friability
was calculated from the loss in weight as
given in equation as below. The weight loss
should not be more than 1 % [17].
Friability (%) = [(Initial weight- Final
weight) / (Initial weight)] x 100
2.3.3. Content Uniformity
In this test, 20 tablets were randomly
selected and the percent drug content was
determined. The tablets contained not less than
85% or not more than 115% (100±15%) of the
labeled drug content can be considered as the
test passed [17].
2.3.4. Assay
Drug content was determined by weighing
randomly selected tablets, pulverizing to a fine
powder. The powder equivalent to 100 mg
Clopidogrel was weighed and dissolved in 10
ml of Distilled water in volumetric flask, the
volume was adjusted to 100 ml with Phosphate
buffer pH 6.8 and the solution was filtered. An
aliquot of 1.0 ml of solution was diluted to 10
ml Phosphate buffer pH 6.8 in separate
volumetric flask. The drug content was
determined spectrophotometrically at 324 nm
[6].
2.3.5. Thickness
Thickness of the all tablet formulations
were measured using vernier calipers by
placing tablet between two arms of the vernier
calipers [17].
2.3.4. Wetting Time
To measure wetting time of the tablet, a
piece of tissue paper folded twice was placed
in a small petri dish (Internal Diameter is= 6.5
cm) containing 5 ml of Distilled water. A
tablet placed on the paper, and the time for
complete wetting of the tablet was measured in
seconds [18-19].
2.3.5. In-vitro Dissolution Study
The in-vitro dissolution study for the
Clopidogrel Fast Dissolving tablets were
carried out in USP XXIII type-II dissolution
test apparatus (Paddle type) using 900 ml of
Phosphate buffer pH 6.8 as dissolution
medium at 50 rpm and temperature 37±0.5°C.
At predetermined time intervals, 5 ml of the
samples were withdrawn by means of a
syringe fitted with a pre-filter, the volume
withdrawn at each interval was replaced with
the same quantity of fresh dissolution medium.
The resultant samples were analyzed for the
presence of the drug release by measuring the
absorbance at 324 nm using UV Visible
spectrophotometer after suitable dilutions. The
determinations were performed in triplicate
(n=3) [6].
2.3.6. Disintegration Test
Disintegration of fast disintegrating tablets
is achieved in the mouth owing to the action of
saliva; however amount of saliva in the mouth
is limited and no tablet disintegration test was
found in USP and IP to simulate in vivo
conditions. A modified method was used to
determine disintegration time of the tablets. A
cylindrical vessel was used in which 10 mesh

67
screen was placed in such way that only 2 ml
of disintegrating or dissolution medium would
be placed below the sieve. To determine
disintegration time, 6 ml of Sorenson’s buffer
(pH 6.8), was placed inside the vessel in such
way that 4 ml of the media was below the
sieve and 2 ml above the sieve. Tablet was
placed on the sieve and the whole assembly
was then placed on a shaker. The time at
which all the particles pass through the sieve
was taken as a disintegration time of the tablet.
Six tablets were chosen randomly from the
composite samples and the average value was
determined.
2.3.7. Kinetic Modeling of Drug Release
The dissolution profile of all the
formulations was fitted in to zero-order, first-
order, Higuchi and Korsmeyer-peppas models
to ascertain the kinetic modeling of drug
release [21-24].
3. Results and Discussion
Fast Dissolving tablets of Clopidogrel
were prepared and optimized by 32
factorial
design in order to select the best combination
of different Superdisintegrants, Crospovidone,
Croscarmellose sodium and also to achieve the
desired rapid release of drug from the dosage
form(by Disintegrating quickly). The two
factorial parameters involved in the
development of formulations are quantity of
Crospovidone & Croscarmellose sodium as
independent variables (X1, X2), and in vitro
dissolution parameters such as t50% , t90% ,
wetting time and disintegrating time as
dependent variables. Totally nine formulations
were prepared using 3 levels of 2 factors and
all the formulations containing 100 mg of
Clopidogrel were prepared as a Fast
Dissolving tablet dosage form by Direct
Compression technique as per the formulae
given in Table 2.
All the prepared tablets were evaluated for
Table 2. Formulae for the preparation of Clopidogrel fast dissolving tablets as per experimental design.
Name of Ingredients
Quantity of Ingredients per each Tablet (mg)
F1 F2 F3 F4 F5 F6 F7 F8 F9
Clopidogrel 75 75 75 75 75 75 75 75 75
Avicel pH-101 71 76 81 76 81 86 81 86 91
Crospovidone 25 25 25 20 20 20 15 15 15
Croscarmellose sodium 25 20 15 25 20 15 25 20 15
Magnesium Stearate 2 2 2 2 2 2 2 2 2
Talc 2 2 2 2 2 2 2 2 2
Total Weight 200 200 200 200 200 200 200 200 200

68
different post compression parameters, drug
content, mean hardness, friability, mean
thickness, Weight variation as per official
methods and results are given in Table 3. The
hardness of tablets was in the range of
3.175±0.13-3.375±0.15 Kg/cm2
. Weight loss
in the friability test was not more than 0.67%.
Drug content of prepared tablets was within
Table 3. Post-compression parameters for the formulations.
S.No Formulati
on
Code
Hardness
(kg/cm2
)
Thickne
ss
(mm)
Friabilit
y (%)
Weight
Variation(
mg)
Drug
Content
(%)
Wetting
Time(
sec)
Disinte
gration
Time
(sec)
1 F1 3.375±0.15
4.79±0.1
4
0.6±0.2 200.71±0.9 99.86±0.25
20.59±1.
4
10±1.4
2 F2 3.29±0.14
4.825±0.
16
0.66±0.3 201.48±1.9 99.69±0.70
20.66±1.
5
11±1.5
3 F3 3.29±0.15
4.76±0.1
5
0.64±0.1 200.69±1.1 99.68±0.50
22.91±1.
7
11±1.7
4 F4 3.275±0.15
4.765±0.
10
0.64±0.2 200.57±2.2 99.78±0.40
22.50±1.
3
11±1.3
5 F5 3.175±0.13 4.8±0.12 0.54±0.3 201.50±1.1 99.61±0.90
22.58±1.
4
12±1.4
6 F6 3.18±0.15
4.735±0.
11
0.67±0.0
4
201.06±2.0 99.60±0.70
24.23±1.
6
13±1.6
7 F7 3.378±0.16
4.715±0.
12
0.63±0.3 200.50±1.4 99.20±0.25
22.32±1.
3
11±1.3
8 F8 3.275±0.14
4.75±0.1
2
0.54±0.4 199.70±0.3 99.03±0.70
22.40±1.
35
12±.1.4
9 F9 3.28±0.16
4.685±0.
11
0.64±0.4 200.47±0.9 99.03±0.5
24.65±1.
6
13±1.6
Figure1. Comparative zero order plots for formulation f1-f9.

69
acceptance range only. The wetting time of
tablets was in the range of 20.59±1.4-
24.65±1.6 sec. The disintegration time of
tablets was in the range of 10±1.4-13±1.6 sec.
Results for all Post-compression parameters
were tabulated or shown in table 3. In-vitro
dissolution studies were performed for
prepared tablets using Phosphate buffer pH 6.8
as a dissolution media at 50 rpm and
temperature 37±0.5°C. The In-vitro
dissolution profiles of tablets are shown in
figure 1 and wetting time chart, disintegration
time charts were shown in figure 2-3
respectively.The dissolution parameters are
given in Table 4. Cumulative % Drug release
of factorial design formulations F1-F9 at 1 Hr
was found to be in the range of 94.95-97.145
%. From the result it reveals that the release
rate was higher for formulations containing
high level of Crospovidone/Croscarmellose
sodium compared with other formulations
containing Lower level, due to high
concentration of Superdisintegrant in
combination, showing various disintegration
mechanism such as wicking and swelling etc
more compared with lower concentration and
alone, drug may release rapidly and shows
improved bioavailability. Therefore, required
release of drug can be obtained by
Figure 2.Wetting time chartfor formulation F1-F9.
Figure 3. Disintegration time chart for formulation F1-F9.

70
manipulating the composition of
Crospovidone and Croscarmellose sodium.
Variation was observed in the wetting time,
disintegrating time, t50%
,
and t90% due to
formulation variables. Formulation F1
containing 25 mg of Crospovidone, 25 mg of
Croscarmellose sodium showed promising
dissolution parameter (wetting time=
20.59±1.4sec, disintegrating time = 10±1.4sec,
t50% = 11.070min, t90% = 36.785 min). The
difference in burst effect of the initial time is a
result of the difference in the concentration of
Superdisintegrants mixtures. This reveals that
increased concentration of superdisintegrants
resulted in a corresponding decrease in the
wetting Time, which might be due to the result
of wicking and other possible disintegrating
mechanisms. Disintegration time is directly
proportional to wetting time.
The In -vitro dissolution data of
Clopidogrel Fast Dissolving formulations
was subjected to goodness of fit test by linear
regression analysis according to zero order and
first order kinetic equations, Higuchi’s and
Korsmeyer-Peppas models to assess the
mechanism of drug release. The results of
linear regression analysis including regression
coefficients are summarized in Table 4. It was
observed from the above that dissolution of all
the tablets followed first order kinetics with
co-efficient of determination (R2
) values in the
range of 0.932-0.956. The values of r of
factorial formulations for Higuchi’s equation
was found to be in the range of 0.909-0.934,
which shows that the dissolution data fitted
well to Higuchi’s square root of time equation
confirming the release followed diffusion
mechanism. Kinetic data also treated for
Peppas equation, the slope (n) values ranges
from 0.210-0.260 that shows Fickian diffusion
mechanism. Polynomial equations were
derived for wetting time, disintegrating time,
Table 4. Regression analysis data of 32
factorial design formulations of Clopidogrel fast dissolving tablets.
S.NO
Formulation
Code
KINETIC PARAMETERS
ZERO ORDER FIRST ORDER HIGUCHI
KORSMEYER-
PEPPAS
a b r a b r a b r a b r
1 F1 37.423 1.510 0.759 1.767 0.027 0.955 16.579 13.263 0.914 0.226 1.405 0.866
2 F2 36.744 1.511 0.765 1.771 0.026 0.955 16.094 13.227 0.917 0.230 1.406 0.867
3 F3 35.625 1.509 0.774 1.794 0.025 0.956 15.386 13.118 0.923 0.239 1.408 0.870
4 F4 37.516 1.500 0.756 1.753 0.026 0.948 16.691 13.202 0.912 0.219 1.401 0.865
5 F5 36.838 1.501 0.762 1.759 0.025 0.947 16.205 13.166 0.916 0.224 1.402 0.866
6 F6 35.718 1.499 0.771 1.782 0.024 0.950 15.498 13.057 0.921 0.232 1.403 0.869
7 F7 37.441 1.478 0.752 1.739 0.024 0.932 16.795 13.038 0.909 0.210 1.392 0.865
8 F8 36.762 1.479 0.758 1.748 0.023 0.933 16.310 13.001 0.913 0.215 1.393 0.867
9 F9 33.450 1.514 0.794 1.832 0.024 0.959 13.919 12.989 0.934 0.260 1.415 0.875
10 MP 37.363 1.513 0.759 1.744 0.026 0.946 16.399 13.307 0.915 0.223 1.404 0.861
F1 to F9 are factorial formulations, r-correlation coefficient, a-Intercept, b-Slope and MP-Marketed Product.

71
t50% , and t90% values by backward stepwise
linear regression analysis using PCP Disso
software and response surface plots were
constructed using SIGMAPLOT V13
software. The response surface plots were
shown in figure 4-7 for wetting time,
disintegrating time, t50% , and t90% using X1 and
X2 on both the axes respectively. The
dissolution data (Kinetic parameters) of
factorial formulations F1 to F9 are shown in
Table 5.
Polynomial equation for 3² full factorial
designs is given in Equation
Y= b0+b1 X1+b2 X2+b12 X1X2+b11 X1²+b22
X2²…
Where, Y is dependent variable, b0
arithmetic mean response of nine batches, and
b1 estimated co-efficient for factor X1. The
main effects (X1 and X2) represent the average
result of changing one factor at a time from its
low to high value. The interaction term (X1X2)
shows how the response changes when two
factors are simultaneously changed. The
polynomial terms (X1² and X2²) are included to
investigate non-linearity. Validity of derived
equations was verified by preparing two check
point formulations of intermediate
concentration (C1, C2).
The equations for Wetting time,
disintegrating time, t50% , and t90% developed as
follows.
Y1= 22.538-0.808X1-1.063X2+0.0025X1X2-
0.808 X1
2
+0.986X2
2
(for Wetting time)
Figure 4. Response Surface plot for Wetting Time. Figure 5. Response surface plot for disintegration time.
Figure 6. Response Surface plot for t50%. Figure 7. Response Surface plot for t90%.

72
Y2= 11.556-0.667X1-0.833X2+0.25 X1X2-
0.667 X1
2
-0.167 X2
2
(for Disintegration time)
Y3= 12.16-0.617X1-0.328X2-0.256
X1X2+0.104 X1
2
-0.125 X2
2
(for t50%)
Y4 = 40.393-2.050X1-1.09X2-0.851
X1X2+0.345 X1
2
-0.418 X2
2
(for t90%)
The positive sign for co-efficient of X1 in
Y1, Y2, Y3, and Y4 equations indicates that as
the concentration of Crospovidone decreases,
wetting time, disintegrating time, t50% , and t90%
value increases. In other words, the data
demonstrate that both X1 (amount of
Crospovidone) and X2 (amount of
Croscarmellose sodium) affect the time
required for drug release (Wetting time,
disintegrating time, t50%and t90%). From the
results, it can be concluded that an increase in
the amount of the Superdisintegrant leads to
decrease in disintegration time of the dosage
form and drug release pattern may be changed
by appropriate selection of the X1 and X2
levels. The dissolution parameters for
predicted from the polynomial equations
derived and those actual observed from
experimental results are summarized in table
6. The closeness of predicted and observed
values for wetting time, disintegrating time, t50%
,and t90% indicates validity of derived equations
Table 5. Dissolution parameters of Clopidogrel fast dissolving tablets 3² full factorial design batches.
S.NO
FORMULATION
CODE
KINETIC PARAMETERS
t1/2 (Min) t90% (Min) WT(Sec) DT(Sec)
1 F1 11.070 36.785 20.59 10
2 F2 11.570 38.446 20.66 11
3 F3 12.081 40.144 22.91 11
4 F4 11.610 38.579 22.50 11
5 F5 12.068 40.103 22.58 12
6 F6 12.581 41.807 24.23 13
7 F7 12.677 42.126 22.32 11
8 F8 13.081 43.467 22.40 12
9 F9 12.664 42.083 24.65 13
10 MP 11.573 38.457 18.98 10
Table 6. Dissolution parameters for predicted and observed values for check point formulations.
FORMULATION
CODE
PREDICTED VALUE ACTUAL OBSERVED VALUE
WT(Sec) DT(Sec)
t50%
(min)
t90%
(min)
WT(Sec) DT(Sec)
t50%
(min)
t90%
(min)
C1 23.509 12.16 12.560 41.732 23.619 12.28 12.652 41.898
C2 21.638 10.66 11.614 38.592 21.690 10.93 11.721 39.012

73
for dependent variables. The response surface
plots were presented to show the effects of X1
and X2 on wetting time, disintegrating time,t50%
and t90%. The final best (Optimized)
formulation (F5) is compared with marketed
product (PLAVIX-75) shows similarity factor
(f2) and 91.3936, difference factor (f1) 1.203
(There is no significant difference in drug
release (becausetcal <0.05).
4. Conclusion
The present research work envisages the
applicability of Superdisintegrants such as
Crospovidone and Croscarmellose sodium in
the design and development of Fast Dissolving
tablet formulations of Clopidogrel utilizing the
32
factorial design. From the results it was
clearly understood that as the concentration of
Superdisintegrant increases the release rate of
drug was RAPID (Improved Solubility) and
both of these Superdisintegrants can be used in
combination since do not interact with the
drug which may be more helpful in achieving
the desired fast dissolving of the dosage form
for rapid action and improved bioavailability.
The optimized formulation followed Higuchi’s
kinetics while the drug release mechanism was
found to be Fickian diffusion, first order
release type. On the basis of evaluation
parameters, the optimized formulation F1 may
be used for the effective management of Acute
Coronary Syndrome (ACS), Hypertension,
Heart Attack, and Stroke. This may improve
the patient compliance by showing rapid
action via disintegration without difficulty in
swallowing and side effects which will
ultimately improve the therapeutic outcome.
We could be able to minimize the per oral cost
of the formulation.
Acknowledgements
The author would like to thank
Management, Principal, Teaching, Non-
teaching Staff of Narasaraopeta Institute of
Pharmaceutical Sciences, Narasaraopet,
Guntur (D.t), A.P., India for providing support
for successful completion of research work.
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