Spectrophotometric Method for Simultaneous
Estimation of Nimesulide and Diclofenac Sodium in
Pharmaceutical Dosage Forms
S.
Rawat1* and Akhilesh Gupta2
1Shri Bhagwan College
of Pharmacy, Aurangabad (M.S.)
2Kunwar Haribansh Singh College of
Pharmacy, Jaunpur (U.P)
*Corresponding Author E-mail: swati_r@k.st
ABSTRACT:
A simple accurate spectrophotometric method has been developed for simultaneous
estimation of nimesulide and diclofenac
sodium. The method involves solving of simultaneous equation based on
measurement of absorbance at two wavelengths i.e., at 276 nm and 395 nm.
KEYWORDS: Nimesulide, Diclofenac
sodium, Simultaneous equation and UV spectrophotometry
INTRODUCTION:
Nimesulide is a COX-2 inhibitor1 and Diclofenac sodium
is an NSAID2, 3. Both are
extensively used for the treatment of inflammatory conditions like
osteoarthritis, rheumatoid arthritis etc. The combination may be given to
patients not responding to monotherapy.
Spectrophotometric and HPLC methods4 have been reported for assay of
diclofenac sodium while colorimetric5 spectrophotometric6-9
and flourimetric10 methods have been reported for nimesulide.
Simultaneous determination of nimesulide
and diclofenac sodium by spectrophotometric
method has not been reported so far. The present study illustrates a simple,
accurate, economical and reproducible procedure for simultaneous spectrophotometric estimation of nimesulide
and diclofenac sodium in two component soft capsule
formulation
Material:
The drug was obtained from Dr Reddy’s Pharmaceuticals
(India), UV visible spectrophotometer Chemito 2100
model (India), solvents used are phosphate buffer pH 7.2, Methanol. (Analytical
grade).
Procedure:
The standard curve was determined for each of the drug
independently. Accurately weighed nimesulide (10mg)
was dissolved in 10 ml methanol and further diluted to get a stock solution of
100 µg/ml. This solution was diluted further to give standard concentrations of
2,4,6,8 and 10 µg/ml. Absorbances of these solutions
were measured at 276 and 395 nm. The absorptivities
for the two drugs are presented in table I. The optical characteristics and
regression equations for the calibration curves are presented in table II.
The method employed simultaneous equation using Cramer’s
rule and matrices. A set of two simultaneous equations was framed using the absorptivity coefficient values as given below:
A1=21.21XC1-83.86 XC2 (I)
A2=53.164XC1-2.336XC2 (II)
Where C1 and C2 are concentration
of nimesulide and diclofenac
sodium respectively in gms / litre
in the sample solution. A 1 and A2 are the absorbance of
the sample solutions measured at 276 and 395 nm respectively. 21.21 and 83.86
are the absorptivities at 276nm while 53.164 and 2.336
are the absorptivities at 395 nm of nimesulide and diclofenac sodium
respectively.
|
Sr. No. |
Concentration (µg/ml. ) |
Absorptivity
at 276 nm. |
Absorptivity
at 395 nm. |
|||
|
NIM |
DIC |
NIM |
DIC |
NIM |
DIC |
|
|
1 |
2 |
2 |
21.50 |
84.50 |
53.46 |
2.52 |
|
2 |
4 |
4 |
21.51 |
84.32 |
53.31 |
2.28 |
|
3 |
6 |
6 |
21.21 |
83.95 |
53.14 |
2.16 |
|
4 |
8 |
8 |
21.01 |
83.65 |
53.01 |
2.75 |
|
5 |
10 |
10 |
20.86 |
82.92 |
52.9 |
1.97 |
|
Mean |
- |
- |
21.21 |
83.86 |
53.164 |
2.336 |
|
S.D. |
- |
- |
0.114 |
0.248 |
0.089 |
0.121 |
n=3 ,
NIM= Nimesulide, DIC= Diclofenac sodium.
Table
2: Optical Characteristics and regression equation
|
Sr. No. |
Parameters |
Values |
||
|
NIM |
DIC |
|||
|
1 |
lmax |
395 |
276 |
|
|
2 |
Beer’s Law limits (µg/ml.) |
0-15 |
0-15 |
|
|
3 |
Molar Absorptivity |
1.724 X 104 |
2.637 X 104 |
|
|
4 |
Sandell’s sensitivity |
1.937 X 10-4 |
1.242 X 10-4 |
|
|
5 |
Regression Equation |
Slope |
0.0524 |
0.0819 |
|
Intercept |
0.05 |
0.015 |
||
|
Correlation Coefficient |
0.999 |
0.999 |
||
n=3
NIM= Nimesulide, DIC= Diclofenac sodium.
Table
3: Analysis Data of Tablet formulations
|
Sr. No. |
Tablet sample |
Level claim mg/tab |
Amount found mg/tab |
% of level claim |
S.D. |
C.O.V.% |
|
1. |
Brand A NIM DIC |
100 50 |
98.3 48.7 |
98.2 97.4 |
0.75 0.80 |
0.765 0.82 |
|
2. |
Brand B NIM DIC |
100 50 |
99.2 49.2 |
99.2 98.4 |
0.62 0.85 |
0.62 0.86 |
n=3 NIM= Nimesulide, DIC= Diclofenac sodium.
Table
4: Recovery studies
|
Sr. No. |
Concentration of added drug to final solution.
(µg/ml.) |
% Recovery |
||||
|
Sample A |
Sample B |
|||||
|
NIM |
DIC |
NIM |
DIC |
NIM |
DIC |
|
|
1. |
1 |
1 |
99.5 |
100.1 |
99.4 |
98.9 |
|
2. |
2 |
2 |
99.2 |
99.8 |
98.7 |
98.2 |
n=3
NIM= Nimesulide, DIC= Diclofenac sodium.
By applying the Cramer’s rule and matrices to equation
(I) and (II), concentration C1 and C2 can be obtained as –
C1= A2 X 83.86- A1 X 2.336 (III)
4408.79
C2= A1 X 53.164- A2 X 21.21 (IV)
4408.79
Preparation and Analysis of
tablet sample solution:
Ten soft capsules were weighed contents containing drug
equivalent to 100mg of nimesulide and 50 mg of diclofenac sodium were emptied into a stoppered
volumetric flask 20 ml of methanol added to it, sonicated
for 20 min. and the rest of the volume
was then made up with phosphate buffer. The solution was further diluted to
give 10 µg/ml of nimesulide
and 5µg/ml of diclofenac sodium. Then absorbances of sample solutions were recorded at 276 nm and
395 nm as A1 and A2 respectively and concentration of the
two drugs in sample were determined using equation (III) and (IV). The analysis
was carried out in triplicate for soft capsule formulation of two different
manufacturers. The results of analysis of capsule formulations are shown in
table III.
Recovery studies:
To study the accuracy, reproducibility and precision of
the proposed method, recovery studies were carried out by addition of standard
drug solution to preanalysed sample. Results of
recovery studies were found to be satisfactory and are presented in table IV.
RESULTS AND DISCUSSION:
The proposed method for simultaneous estimation of nimesulide and diclofenac sodium
in combined dosage forms was found to be simple, accurate, economical and
rapid. The values of coefficient of variation were satisfactory low and
recoveries were closed to 100% for both the drugs.
The method employs solving of simultaneous equations.
Once the equations are determined analysis requires only the measuring of the
absorbance of the sample solution at the two wavelengths selected, followed by
a few simple calculations.
The proposed method is fast accurate and precise for
the determination of nimesulide and diclofenac sodium in combined soft capsule formulations.
Hence, it can be employed for routine analysis in Quality Control Laboratories.
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Received on 09.09.2011 Accepted on 18.10.2011
© Asian Pharma
Press All Right Reserved
Asian J. Pharm.
Ana. 1(4): Oct. - Dec. 2011; Page 85-87