INTRODUCTION:

Montelukast Sodium is a leukotriene antagonist, and it is used as anti-asthmatic and also in the treatment of allergic rhinitis and chemically it is 1-[[[(1R)-1-[3-1(E)-2-7chloro2quinolinyl)ether]phenyl]3 [2(1hydroxy1methylethyl) phenyl]propyl] thio] methyl]cycly propancacetic acid^1-9, Literature described cited for the quantification of, montelukast Sodium HPLC and derivative spectrophotometric methods spectrofluorometric methods^10-14 for its determination in pharmaceutical determination alone and with other combination. Levocetirizine hydrochloride. It is active Isomer (R-form) of cetirizine. It selectively inhibits Histamine H₁-receptors chemically it is [2-[4-[(4-chlorophenyl)-phenylmethyl]-1-piperazinyl] ethoxy] acetic acid, Literature described cited for the quantification of levocetirizine hydrochloride RP-HPLC, UV Spectrophotometric methods^15-20 for its determination in pharmaceutical determination alone and with other combination.

The present paper describes a simple, rapid, accurate, and reproducible method for the simultaneous estimation of MONT and LVC in tablet formulation by absorption corrected for interference method, first order derivative method.

EXPERIMENTAL:

Materials:

MONT and LVC were gift sample from Ranbaxy laboratories ltd., Gurgaon. The commercial fixed dose combination product (L-Montus containing 10 mg montelukast Sodium and 5 mg levocetirizine Hydrochloride) was procured from the local market. Methanol AR grade was procured from Qualigens fine chemicals, Mumbai.

Equipments:

Shimadzu UV-Visible spectrophotometer with 1 cm matched quartz cells was used for the measurement of absorbance. Shimadzu AX-200 electronic balance was used for the weighing the samples. Class ^‘A^’ volumetric glassware were used.

PROCEDURE:

Absorption corrected for interference method:

Development of the method:

The solution of MONT and LVC were prepared separately in methanol at a concentration of 10µg / ml. They were scanned in the wavelength range 210-400. The wavelength selected for MONT analysis was 280.2 nm and for LVC is 232.2nm, after examining the overlain, at 280.2 nm LVC shows zero absorbance where at 232.2 nm both the drugs shows absorbance. The overlain spectra of the drugs are shown in Figure.1.

Figure.1.Overlain absorption spectra of Montelukast sodium and Levocetirizine hydrochloride in methanol

Linearity:

Standard stock solution was prepared by dissolving 100mg of each standard drug samples in 100 ml volumetric flask separately and the volume was made up with methanol to get a concentration of 1mg / ml. From this, suitable dilutions were made in methanol to get the working standard solutions of 5-30 µg / ml for MONT and LVC respectively. Six replicate analyses were carried out. Absorbance VS concentration was plotted to obtain the calibration graph. Both the drugs obeyed Beers law with the above concentration range with the R²values of 0.9998 and 0.9992 for MONT and 0.9991 for LVC respectively shown in Figure 2, 3 , and 4 and in Table 1, 2.

Table.1.Beers Law concentration to confirm linearity of Levocetirizine Hydrochloride

(Absorption correction method)

Concentration µg /ml	Absorbance 230.2nm
5	0.226
10	0.403
15	0.591
20	0.767
25	0.958
30	1.146

Table.2.Beers Law concentration to confirm linearity of montelukast Sodium

(Absorption correction method)

Concentration µg /ml	Absorbance
Concentration µg /ml	230.2	282.2nm
5	0.237	0.197
10	0.408	0.378
15	0.613	0.572
20	0.807	0.777
25	1.003	0.973
30	1.196	1.166

Figure.2.Calibration curve of Montelukast sodium at 282.2 nm

-Absorbance correction Method

Figure.3.Calibration curve of Montelukast sodium at 230.2 nm

-Absorbance correction Method

Figure.4.Calibration curve of Levocetirizine hydrochloride at 230.2 nm -Absorbance correction Method

Analysis of the marketed formulation:

20 tablets were weighed and finely powdered. An accurately weighed quantity of powder equivalent to about 10 mg of MONT and 5 mg of LVC was transferred to 100 ml of volumetric flask.

Table.3.Assay of commercial formulations (Absorption correction method)

Drug

Sample No.

Amount Labeled

( mg/tab)

Amount estimated (mg/tab)

Percentage of amount found (%)

Formulation

Montelukast sodium

10.136

10.140

10.136

10.138

10.100

101.36

101.41

101.36

101.38

101.00

Levocetirizine

Hydrochloride

4.92

4.90

4.91

4.90

98.56

98.14

98.19

98.35

98.19

Table.4.Recovery study data (Absorption correction method)

Drug

Amount

Added (µg)

Amount Found (µg)

Percentage recovery (%)

S.D.

% RSD

S.E.

Formulation

Montelukast Sodium

5.91

7.85

9.89

98.62

98.20

98.96

0.3807

0.38

0.1554

Levocetirizine hydrochloride

5.91

8.06

10.17

98.62

100.80

101.73

1.596

1.59

0.6516

Table.5.Statistical validation (Absorption correction method)

Drug

Lable claim ( mg/tab)

Amount estimated (mg/tablet)

S.D.

% RSD

S.E

Montelukast

Sodium

10.12

0.155403

0.153386

0.063443

Levocetirizine

Hydrochloride

4.90

0.159123

0.161924

0.064962

The content of the flask were mixed with methanol by intermittently shaken so as to dissolve and extract the active ingredient and then made up to the volume with the same solvent. The solution was filtered and the filtrate was further diluted with methanol to get final concentration of 10µg / ml of MONT and 5 µg / ml LVC and the absorbance values were recorded at 230.2 nm and 282.2nm. The amount of MONT and LVC were determined by absorbance corrected for interference method. (Table 3)

Recovery studies:

To determine the accuracy of the method, recovery study was performed using the method of addition. To the preanalysed marketed formulation powder equivalent to 10 mg of MONT and 5 mg of LVC, an accurately weighed quantity of raw materials is added at 3 levels viz 60% , 80%, 100 %. For both drugs and the total drug content were determined as described for formulation , the percentage recovery was determined and the result are given in Table -4

First derivative method:

Development of the method:

The solution of MONT and LVC were prepared separately in methanol at a concentration of 10µg / ml. They were scanned in the wavelength range 210-400. Data were recorded at an interval of 1 nm. Then the spectra of the two drugs were derivatised to obtain first order derivative spectra. After examining the overlain first order derivative spectra, wavelength was selected where one drug showed zero crossing and other drug showed substantial absorbance. The wavelength selected for MONT analysis was 270.8 nm, where LVC has zero absorbance and the wavelength selected for LVC analysis was 224 nm. Where the absorbance of MONT is zero. The overlain derivative spectra of the drugs are shown in Figure 5

Figure.5. Overlain First Derivative spectra of Montelukast sodium and Levocetirizine hydrochloride

Linearity:

Standard stock solution was prepared by dissolving 100mg of each standard drug samples in 100 ml volumetric flask separately and the volume was made up with methanol to get a concentration of 1mg / ml. From this, suitable dilutions were made in methanol to get the working standard solutions of 10-60 µg / ml for MONT and 10-35µg / ml LVC respectively. Six replicate analysis were carried out. Absorbance VS Concentration were plotted to obtain the calibration graph. Both the drugs obeyed Beers law with the above concentration range with the R² values of 0.9995 for MONT and 0.9999 for LVC respectively shown in Figure 6, and 7 and in Table 6, 7.

Table.6.Beers Law concentration to confirm linearity of Levocetirizine Hydrochloride (Derivative Sectrophotometry)

Concentration µg /ml	224nm
10	0.0172
15	0.0257
20	0.0346
25	0.0429
30	0.0513
35	0.0598

Figure.6.Calibration curve of Levocetirizine hydrochloride at 224 nm -First Derivative Method

Table.7.Beers Law concentration to confirm linearity of Montelukast sodium (Derivative Spectrophotometry)

Concentration µg /ml	270.8nm
10	0.0073
20	0.0148
30	0.0222
40	0.0293
50	0.0356
60	0.0432

Figure.7.Calibration curve of Montelukast sodium at 270.8 nm -First derivative Method

Analysis of the marketed formulation:

20 tablets were weighed and finely powdered. An accurately weighed quantity of powder equivalent to about 20 mg of MONT and 10 mg of LVC was transferred to 100 ml of volumetric flask. The content of the flask were mixed with methanol by intermittently shaken so as to dissolve and extract the active ingredient and then made up to the volume with the same solvent. The solution was filtered and the filtrate was further diluted with methanol to get final concentration of 20µg / ml of MONT and 10 µg / ml LVC and the absorbance values were recorded at 270.8 nm and 224nm. The amount of MONT and LVC were determined and the results are given in the (Table. 8)

Recovery studies:

To determine the accuracy of the method, recovery study was performed using the method of addition. To the preanalysed marketed formulation powder equivalent to 10 mg of MONT and 5 mg of LVC, an accurately weighed quantity of raw materials is added at 3 levels viz 60%, 80 %, 100 %. For both drugs and the total drug content were determined as described for formulation , the percentage recovery was determined and the result are given in (Table 9 )

Table.8.Assay of commercial formulations (First Derivative method)

Drug

Sample No.

Amount Labeled (mg/tab)

Amount estimated (mg/tab)

Percentage of amount found (%)

Formulation

Montelukast sodium

9.779

10.029

10.026

10.308

10.029

9.946

97.79

100.29

103.08

100.29

99.46

Levocetirizine

Hydrochloride

5.036

4.982

4.926

5.066

5.038

4.982

100.72

96.48

98.52

101.32

100.76

99.64

Table.9.Recovery study data (First derivative method)

Drug

Amount

Added (µg)

Amount Found (µg)

Percentage recovery (%)

S.D.

% RSD

S.E.

Formulation

Montelukast sodium

6.01

7.95

10.10

100.16

99.47

101.05

0.766

0.764

0.312

Levocetirizine

Hydrochloride

5.91

7.84

9.89

98.61

99.37

98.90

0.383

0.387

0.156

RESULTS AND DISCUSSIONS:

Selected drug combination MONT and LVC is available in fixed dosage combinations mainly in tablet dosage forms. Many methods are available for estimation of the same as single components (or) in combination with other drugs. Hence, simple, accurate, precise UV–Spectrophotometric method for simultaneous estimation of MONT and LVC was developed and validated. From the overlain spectra, it was concluded that, the simultaneous equation method may not be possible for the simultaneous estimation of these drugs, hence, the alternate method for the simultaneous estimation of MONT and LVC is by using absorbance corrected for interference method and first derivative method.

Absorbance corrected for interference method

Both the drugs solubility was studied as per IP standard in various solvents from this common suitable solvent, methanol was selected. From the stock solution adequate dilutions were made to produce 10 µg / ml solutions of MONT and LVC, they were scanned in the range of 210-400 nm. The λ _max of MONT and LVC has found to be 282.2 nm and 230.2 nm. Overlain spectra of the drugs were taken and presented in Figure.1. From the overlain spectra, it has founded that MONT shows significant absorbance at 230.2 nm while LVC shows zero absorbance at 282.2 nm, so the two wavelengths (282.2 nm and 230.2 nm) were selected for estimation of both drugs by absorbance corrected for interference method. Different aliquots of MONT and LVC were prepared in the concentration range of 5-30µg / ml. The absorbance of solutions were measured at 230.2 nm and 282.2 nm The calibration curve was plotted using concentration against absorbance and the calibration curve shown in Figures – 2,3,and 4.. The correlation coefficients for the both drugs are within limit and the concentration obeys Beers Law in the selected concentration range. Hence the concentrations were found to be linear in the selected concentrations. The formulation (L MONTUS), containing 10 mg of MONT and 5 mg of LVC was selected for analysis. 20 tablets were accurately weighed and average weight was founded. Weight equivalent to 10 mg of MONT was weighed and transferred into 100ml volumetric flask. Which was diluted to contain 10 µg /ml of MONT and 5 µg / ml of LVC and the absorbance value are recorded at 230.2 nm and 282.2 nm. Then amount of MONT was determined from the absorbance value of the solution at 282.2 nm where LVC shows zero absorbance and the amount of LVC was calculated from absorbance corrected principle. The amount of six test solutions was determined. The percentage label claim present in tablet formulation was found to be 101.31 % for MONT and 98.27 % for LVC. The amount present in tablet formulation was in good concerned with label claim and shown in the Table -3 and % R.S.D values were found to be 0.153386 and 0.161924 for MONT and LVC. The statistical parameters are presented in Table -5.

The accuracy of the method was performed by recovery studies to the preanalysed formulation, a known quantity of MONT and LVC raw material solutions were added at different levels. The absorbance of the solutions was measured and % recovery was calculated. The % recovery was found to be in the range of 98.55 – 99.96 % for MONT and 98.62 – 101.73 % for LVC hydrochloride. The low % R.S.D value for 2 drugs indicates that this method is very accurate. The recovery data is shown in Table 4.

First order derivative methods

Both the drug solutions (10 µg /ml) were scanned in the range of 210 nm - 400 nm. Then these spectra are derivatised to obtain first derivative spectra, and the overlain spectra of the drugs were taken and presented in the Figure 5.

Montelukast Sodium: Shows peak maxima at 270.8 nm

Levocitirizine hydrochloride: Shows peak maxima at 224 nm. From this we had selected two wavelengths 270.8 nm (MONT) and 224 nm (LVC).

Different aliquots of MONT were prepared in the concentration range of 10-60µg /ml and LVC hydrochloride were prepared in the concentration range of 10-35µg /ml. The absorbance of solutions were measured at 270.8nm and 224nm and the calibration curve was plotted using concentration against absorbance and the calibration curve shown in Figures –6 ,7 The correlation coefficients for the both drugs are within limit and the concentration obeys Beers law in the selected concentration range. Hence the concentrations were found to be linear in the selected concentrations. The tablets were processed same as above method to extract the active ingredients and diluted to contained 20 µg /ml of MONT and 10 µg / ml of LVC the solutions are scanned in the range of 210 - 400 nm and it derivatised to produce first derivative spectra. Then the derivatised values were measured at 270.8 nm and 224 nm and the amount of MONT was determined from the calibration curve of MONT at 270.8nm while the amount of LVC was determined from calibration curve of LVC at 224 nm. The amount of six test solutions was determined. The percentage and amount of six test solutions were determined. The percentage of label claim present in tablet formulation was found to be 100.70 % for MONT and 100.85 % for LVC. The amount present in tablet formulation detected by this method was in good concerned with label claim and shown in Table – 8. % R.S.D values were found to be 0.581791 and 0.466566 for MONT and LVC. The statistical validations are shown in Table 10.

The accuracy of the method was performed by recovery studies to the pre-analyzed formulation, a known quantity of MONT and LVC raw material solutions were added at different levels. The absorbance of the solutions was measured and % recovery was calculated. The % recovery was found to be in the range of 100.16 – 101.05 % for MONT and 98.61 – 98.90 % for LVC. The low % R.S.D value for 2 drugs indicates that this method is very accurate. The recovery data is shown in Table – 9.

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Received on 05.08.2010 Modified on 22.08.2010

Asian J. Research Chem. 4(1): January 2011; Page 104-109