INTRODUCTION:

MK Chemically, 1- [[[ (1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethyl]phenyl]-3-[2-(1-hydroxy-1-methyl-ethyl)phenyl]propyl]thio]methyl]cyclo propaneacetic acid is an anti asthmatic agent (Leucotriene receptor antagonist ). LC chemically, [2-[4-[(4-chlorophenyl)-phenyl methyl]-1-piperazinyl]ethoxy]acetic acid is an anti allergic agent (H₁

receptor antagonist)^1,2. This combination is used to treat allergic rhinitis. Analytical methods for estimation of both the drugs individually and combination with other drugs were reported^3-9. However none of the method was reported for simultaneous estimation of selected combination from combined binary pharmaceutical dosage form.

MATERIALS AND METHODS:

Materials:

An UV-VIS spectrophotometer Schimadzu UV-1700, Japan; single pan electronic balance, Shimadzu AX-200, Japan and Methanol (Analytical grade) were used for the experimental purpose.

Determination of absorbance maxima:

Accurately weighed 25 mg of both the drugs transferred into 25 ml volumetric flask dissolved in methanol and diluted to 25 ml to get concentration of 1mg/ml which was further adequately diluted to get final concentration of 10 mcg/ml.

This diluted solution was utilized to study the spectral character of the drugs. Both the drug solutions were scanned in the spectrum mode over the range of 200-400nm; MK shows absorption maxima at 287 nm whereas LC at 232 nm. The overlain spectra were showed in fig. 1

Method I (Absorbance correction method):

From the overlain spectra (fig.1) 287 nm was selected for determination of MK (where LC shows no absorbance) and 232 nm was then selected where both the drug shows considerable absorbance. From the total absorbance of the both the drugs at 232 nm, Subtracted the absorbance due to MK to produce corrected absorbance i.e. absorbance due to LC alone was calculated. Stock solution of both the drugs were further diluted separately with methanol to get series of standard solutions 1-40 μg/ml of LC and 2-40 μg/ml of MK. The absorbances of standard solutions were measured at selected wavelengths and calibration curve was constructed and absorbtivities (A_1%1cm) for both the drugs were determined. Sample solution was prepared by following manner.

Twenty tablets were weighed and average weight was calculated. It was powdered and weight equivalent to 25 mg of MK was taken in 25ml volumetric flask. The active contents were extracted with methanol which was filtered and further diluted so that final concentration of solution was equivalent to 12 μg/ml of MK. Absorbance of sample solutions were recorded at 287 and 232 nm then amount of both the drugs were calculated by absorbance correction principle.

Method II (Multi wavelength method):

From the overlain spectra, it was studied that LC shows same absorbance at 229 and 232.2 nm which was selected for estimation of MK on the basis of principle that absorbance difference between these two wavelengths in a mixture spectra is directly proportional to concentration of MK (component of interest) and independent of LC (interfering component) another third wavelength, 232 nm was selected for estimation of LC by applying absorbance correction principle. Stock solution of both drugs were further diluted separately with methanol to get series of standard solutions of 5-40 μg/ml. Absorbance were recorded at all the three selected wavelengths and also the difference absorbance of MK at 229 and 232.2 nm were calculated and calibration curve was constructed. The sample solution was prepared as method I which was filtered and further diluted so contain final concentration equivalent to 15 μg/ml of MK and absorbance were recorded at all selected three wavelengths and amount of MK was calculated from difference absorbance of sample solution at 229 and 232.2 nm and amount of LC obtained by applying absorbance correction principle for the measurement at 232nm.

Fig.1: Overlain spectra of two drugs

1. UV spectra of 10 μg/ml Montelukat sodium in methanol. 2.UV spectra of 10 μg/ml Levocetirizine hydrochloride in methanol.

Method III (First order derivative method):

Overlain first order derivative spectra of MK and LC in methanol was shown in fig.2 From the overlain spectra two wavelengths were selected, 231.1(zero crossing point for LC) utilized for estimation of MK, 216.5nm (zero crossing point for MK) utilized for estimation of LC. Stock solution of both drugs were further diluted separately with methanol to get series of standard solutions of 10-40 μg/ml and solutions were scanned and derivatised to produce first derivative spectra and the derivatised values were noted for 216.5 and 231.1nm, calibration curve was constructed. The sample solution was prepared as method I which was filtered and further diluted so contain final concentration equivalent to 25 mcg/ml of MK and sample solution was scanned and derivatised to produce first derivative spectra and derivatised values at 216.5 and 231.1nm was recorded. Amount of both drugs were determined by using respective calibration curves. Results of analysis of commercial formulation by all the above methods were tabulated in Table 1.

Recovery Studies:

To study the accuracy, reproducibility and precision of the above developed methods recovery studies were carried out by addition of standard drug solution to the pre analyzed tablet formulation at three different concentration levels. 2, 4, 6 μg/ml of MK and 1, 2, 3 μg/ml of LC were mixed with pre analyzed formulation solution and analyzed by early described absorption correction method (Method-I). 3, 6, 9 μg/ml of MK and 1.5, 3, 4.5 μg/ml of LC were mixed with pre analyzed formulation solution and analyzed by early described Multi wavelength method (Method-II) and 10, 15, 20 μg/ml of MK and 5, 7.5, 10 μg/ml of LC were mixed with pre analyzed formulation solution and analyzed by early described first derivative method.

Fig-2: Overlain First order derivative spectra of two drugs

1. First derivative spectra of 10 μg/ml Montelukast sodium in methanol. 2. First derivative spectra of 10 μg/ml Levocetirizine hydrochloride in methanol.

RESULTS AND DISCUSSION:

Three simple, accurate, economical, and reproducible UV-Spectrophotometric methods have been developed for simultaneous estimation of MK and LC from combined tablet dosage form using methanol as a solvent. First method involves absorbance correction principle using two wavelengths 232 and 287nm. MK shows linearity in the concentration range of 2-40 mcg/ml at 287 and 232nm. Whereas LC shows 1-40 μg/ml at 232nm. Calibration curve was constructed at 287 nm and 232 nm for MK which has correlation co-efficient (r²) of about 0.9997 and 0.9999 for 287 and 232 nm respectively. Calibration curve for LC was constructed at 232 nm, has correction co-efficient (r²) of about 0.9996. Second method involves use of multi wavelength calculation using difference absorbance at 229.

Table 1: RESULTS OF ANALYSIS OF COMMERCIAL FORMULATION

Method

Label claim(mg/tab)

Average amount estimated(mg/tab)* ±SD

% RSD

Method I

Method II

Method III

10.04 ±0.0444

9.97 ±0.1303

10.01 ±0.1712

4.97 ±0.0582

4.99 ±0.009

5.00 ± 0.0511

0.4422

1.3069

1.71029

1.0826

0.1802

1.0215

0.0181

0.0532

0.0699

0.0237

0.0036

0.0208

* Mean of six observation

Table 2: RESULTS OF RECOVERY STUDY DATA

Method

Amount added (mcg)

Amount founded (mcg)

Average % Recovery ±SD

% RSD

Method I

2.00

3.99

5.94

1.00

2.01

3.01

99.70

±0.6311

100.49

±0.4687

0.6330

0.4664

Method II

1.5

3.0

4.5

2.95

5.58

8.94

1.52

3.00

4.50

98.58

±0.6598

100.49

±0.8524

0.6693

0.8482

Method III

5.0

7.5

9.87

14.98

20.01

4.98

7.48

10.08

99.76

±0.9679

99.82

±0.2288

0.9702

0.2292

and 232.2 nm for estimation of MK where LC shows same absorbance and 232 nm was selected for estimation of LC by applying absorbance correction principle. MK shows linearity in the concentration range of 5-40 μg/ml at 229 nm(r²0.999921) and 232.2 nm (r²0.999795) and the difference absorbance of MK at these two selected two wavelengths shows linearity in the same concentration range and has correlation co-efficient (r²) of about 0.9993. Third method involves make use of first derivative UV-spectrophotometry based on principle that at zero crossing point of one component the other component has substantial absorbance. MK shows linearity in the range of 10-40 μg/ml at 231.1nm (zero crossing point for LC) has correlation coefficients of about0.99970 and LC shows linearity in the range of 10-40 μg/ml at 216.5 nm (zero crossing point for MK). Commercially available binary tablet formulation containing MK-10 mg and LC-5 mg, were analyzed by all the above three methods. The amount detected by all the methods for MK and LC were presented in table1.The amount determined by all the 3 methods were close to label claim. %RSD was calculated and presented in table1 which was found to be less than 2. Recovery studies were carried out by addition of standard drug solution to pre analyzed tablet sample solution at three different concentration levels, the percentage recovery was found to be in the range of 98.08-101.60% and it was presented in table 2. Results of recovery studies were found to be satisfactory

CONCLUSION:

The proposed methods for simultaneous estimation of Montelukast sodium and Levoceterizine hydrochloride in combined tablet dosage form were found to be simple, accurate, precise, economical and rapid. In all the methods

the amount of MK and LC estimated from tablet formulation was nearly close to label claim. Percentage recovery was found to be close to 100% and %RSD was found to be less than 2 for all the three methods. Hence, it can be employed for routine analysis in quality control laboratories.

REFERENCES:

1. The Merck Index. 14^th edn., Merck Research Laboratories Division of Merk and co. Inc, USA, 2006, 1080 and 334

2. Tripathi KD. Essentials of Medical pharmacology. 5^th edn. Jaypee brother’s medical publisher p.Ltd. New Delhi. 2003. 199and205

3. Arayne MS. et al. Determination and Quantification of cetirizine hydrochloride in dosage formulation by RP-HPLC. pak j pharm Sci. 2005 jul;18(3):7-11

4. Choi SO.et al. Stereoselective determination of cetirizine and studies on pharmacokinetics in rat plasma. J Chromatogr B Biomed Sci Appl. 2000 jul 7;744(1):201-6.

5. Paw B. et al. Development and Validation of a HPLC method for the determination of cetirizine in pharmaceutical dosage forms. Pharmazie. 2002 May;57(5):313-5.

6. Alsarra I. et al. Spectroflurimetric determination of montelukast in dosage forms and spiked human plasma. Pharmazie. 2005 Nov;60(11):823-6.

7. AL Omari MM. et al. Effect of light and heat on the stability of montelukast in solution and in its solid state. J pharm Biomed Anal. 2007 Nov 5;45(3):465-71.

8. Ochai I. et al. Determination of montelukast sodium in human plasma by column-swithing high-performance liquid chromatography with fluorescence detection. J Chromatogr B Biomed Sci Appl. 1998 Aug 25;713(2):409-14.

9. Radhakrishna T. et al. Simultaneous determination of Montelukast and Loratadine by HPLC and derivative spectrophotometric methods. J Pharm Biomed Anal. 2003 Feb 26;31(2):359-68.

Received on 21.04.2009 Modified on 24.06.2009

Research J. Pharm. and Tech.2 (4): Oct.-Dec. 2009; Page 743-745