International Journal of Drug Development and Research

Keywords

Lafutidine, Rabeprazole sodium, Anti-ulcer, UV, Methanol.

INTRODUCTION

Lafutidine is chemically 2-(furan-2-ylmethylsulfinyl)- N-[4-[4-(piperidin-1-ylmethyl)pyridin-2-yl]oxybut-2- ethayl]acetamide. Lafutidine is not official in any pharmacopoeias. It is used as anti-ulcering agent as it is the new generation H2 receptor bloker. The structure of Lafutidine as below

Rabeprazole sodium is 2-([4-(3-methoxypropoxy)-3- methyl-2-pyridinyl]-methyl]sulfinyl]-1H

benzimidazole sodium salt is an anti-ulcer drug in the class of proton pump inhibitors that reduce the production of acid by blocking the enzyme (hydrogen-potassium adenosine triphosphatase) in parietal cells and used to treat duodenal ulcers and erosive or ulcerative gastro esophageal reflux disease.The structure of Rabeprazole sodium as below:

The literature survey revealed that various methods of analysis for Lafutidine have been reported which include, LC-ESI-MS, HPLC-MS[6,7,8,9,10,11,12], Tandem MS.HPLC,LC-MS[13,14,15,16,17] and UV Spectroscopic method have been reported for Rabeprazole sodium.But no spectroscopic method have been reported for simultaneous estimation of Lafutidine and rabeprazole sodium in combined dosage form. In this report efforts are made to develop a simple, accurate, precise Q-Absorption ratio method to simultaneous determination of the Lafutidine and Rabeprazole sodium in combined dosage form.The following method was validated according to ICH norms.

Experiment

Chemical and Reagent:

Methanol was ued throughout UV Spectroscopic method development and validation.

Instrumentation:

UV-spectrophotometric method was performed on double beam UV-visible spectrophotometer (Shimadzu, model 1800) having two matched quartz cells with 1 cm light path.

Preparation of standard stock solution(100μg/ml):

Stock solutions were prepared by dissolving rabeprazole sodium and Lafutidine in Methanol as solvent to obtain a concentration of 1mg/1ml(1000ppm) for each compound. From this pipette out 10 ml of solution in another 100 ml volumetric flask and volume was made up with methanol to the mark to give final concentration of 100μg/ml.

Preparation of sample stock solution(100μg/ml):

To measure the Lafutidine and Rabepazole sodium content of tablet (label claim 10 mg Lafutidine and Rabeprazole sodium 20mg per tablet, Lafumac plus capsule by Macleods Pharmaceuticals), twenty capsules were weighed, the mean weight was determined. A weight of the powder equivalent to10 mg Lafutidine and 20mg of Rabeprazole sodium were transferred to a 100 ml volumetric flask containing 50 ml Mehtanol and the mixture was sonicated for 20 min then made up to 100 ml with Methanol gives concentration of 100μg/ml and 200 μg/ml ,respectively . The solution was filtered and filtered solution was diluted to get concentration in ratio 10:20 as lafutidine and Rabeprazole sodium used throughout experiment.

UV-Spectroscopic method:

Q-Absorption ratio method

This method is applicable to the drugs that obey Beer’s law at all wavelengths and the ratio of absorbance at any two wavelengths is a constant value, independent of concentration and path length. The solutions of 20μg/ml and 10μg/ml for Rabeprazole sodium and Lafutidine were scanned in the wavelength range of 400 to 200nm to obtain overlain spectra (fig.3). Two wavelengths, 278.27nm as iso absorptive point and 283.8nm (λmax of Rabeprazole sodium) were selected for the formation of Q-absorbance ratio equation. The calibration curves were determined in the concentration range of 5-30μg/ml and 10-60μgml for Rabeprazole sodium and Lafutidine respectively. The absorptivity coefficients of each drug at both the wavelengths were determined. The concentration of the individual components, Cx and Cy can be calculated by using the following equations.

Cx = (QM-QY/QX-QY) x (A1/ax1)

CY = (QM-QX/QY-QX) x (A2/ay1)

Where A1 and A2 are absorbance of sample solution at iso-absorptive point 278.27nm and 283.8nm λMAX ofRabeprazole sodium respectively, ax1 and ax2 are the absorptivities of the Lafutidine at 278.27nm and 283.8nm respectively and ay1 and ay2 are the absorptivities of the Rabeprazole sodium at 278.27nm and 283.8nm respectively.

Validation of UV-spectrophotometric method:

Linearity ans Range

Six aliquots of each drug solutions were taken from standard stock solution and transferred to 10ml volumetric flask to get a final concentration of 5, 10, 15, 20, 25 and 30μg/ml of Lafutidine and 10, 20, 30, 40, 50 and 60μg/ml of rabeprazole sodium and the volume was completed with the distilled water and each flask content was measured to determine the absorbance at all the selected wavelength. For QAbsorption ratio method the wave lengths selected were 278.27nm (iso absorptive point) and 283.8nm (λmax of Rabeprazole sodium). The absorbance at these two wavelengths for all standard solutions of both Lafutidine and Rabeprazole sodium were measured and the calibration curves and linear regression equation of Lafutidine and Rabeprazole sodium at 278.27nm and 283.8nm were determined.

Precision

In intraday study concentration of two drugs were calculated on the same day at an interval of one hour. In inter day study the concentration of drug contents were calculated on three different days study expresses with in laboratory variation in different days. In both intra and inter-day precision study for the methods %RSD were calculated.

Accuracy

Accuracy of the developed method was confirmed by doing recovery study as per ICH norms at three different concentration levels 50%, 100%, 150% and the values were measured at all wavelengths for Lafutidine and Rabeprazole sodium. This operation was done in triplicate. From the recovery study it was clear that the method is very accurate for quantitative estimation of Lafutidine and Rabeprazole sodium in capsule dosage forms as the statistical results were within the acceptance range.

Limit of Detection and Limit of Quantification

The limit of detection and limit of quantification of Lafutidine and Rabeprazole sodium by proposed methods were determined using calibration standards.LOD and LOQ were calculated as 3.3σ/S and 10σ/S, respectively, where S is the slope of the calibration curve and σ is the standard deviation of response.

Results and discussions

Linearity and range

The linearity of Q- Absorption ratio method was found to be 5-30μg/ml with correlation coefficients of 0.9998 and0.999 at 278.27nm and 283.8nm respectively, the calibration data with %RSD for the method shown in (table-4) and calibration curves are shown in (figure 5, 6, 7, 8, 9 and 10).

Precision

The precision of the method was expressed in terms of % relative standard deviation (%RSD). The %RSD values found to be less than 2 for intra-day and interday precision, which indicate that the proposed method is precise for analysis. The result is expressed in Table 1 and Table 2.

Accuracy

Accuracy of the methods was confirmed by doing recovery studies from marketed formulation at three concentration levels of standard addition. The %recoveries found for Q-Absorption ratio method was found to be 99.09-100.18 and 99.57-99.82 for Lafutidine and Rabeprazole sodium, respectively as shown in table 3.

Limit of Detection and Limit of Quantification

For Q-Absorption ratio method the limit of detection found to be 0.3991 at (278.27nm),0.3694 at (283.8nm) and 1.113at(278.27nm), 1.145 at(283.8nm) for Lafutidine and Rabeprazole sodium, respectively, the limit of quantification found to be 1.2095 at (278.27nm) and 1.1194 at (283.8nm), 2.412 at (278.27nm) and 2.172 at (283.8nm) for both Lafutidine and Rabeprazole sodium as shown in table 9.

Analysis of marketed preparation (Lafumac Plus®) by UV Spectroscopic method

The percentage of Lafutidine and Rabeprazole sodium in the estimated formulation was found to be 98.70% and99.55% as shown in table 5.

CONCLUSION

The present work describes a new, simple,cost effective, accurate, precise method.It is concluded that the described methods have the potential for the application in the quality control laboratory.

Calibration curve for Q-Absorption ratio method:

Tables at a glance

Table 1 Table 2 Table 3 Table 4 Table 5

Figures at a glance

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

References

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