UV Spectroscopic Area under Curve Technique for the Quantification of Acarbose in Tablets

Introduction

Acarbose chemically is (2R, 3R, 4R, 5S, 6R)-5-[(2R,3R,4R,5S,6R)-5-[(2R,3R,4S,5S,6R)-3, 4-dihydroxy-6-methyl-5-[[(1S,4S,5S,6S)-4,5,6-trih ydroxy-3-(hydroxymethyl)cyclohex-2-en-1-yl]ami no]oxan-2-yl]oxy-3,4-dihydroxy-6-(hydroxymethy l)oxan-2-yl]oxy-6-(hydroxymethyl)oxane-2,3,4-tri ol¹ .Acarbose is an alpha glycosidase inhibitor that decreases intestinal absorption of carbohydrates and is used as an adjunctive therapy in the management of type 2 diabetes.²

It was found that variety of methods for quantification of Acarbose have been reported like visible spectrophotometric method, ³ liquid chromatography and capillary electrophoresis of Acarbose⁴ , quantification of Acarbose by liquid chromatography-electro spray Tandem Mass Spectrometry⁵ , and capillary electrophoresis. ⁶ However, there was no Ultraviolet- Visible spectrophotometric method found for the detection of Acarbose. So there was a need for the development of new method.

Materials and Methods

Materials

UV Spectrophotometer (Shimadzu 1800)with 1cm matched quartz cuvettes was used as the instrument for data collection and analysis. Methanol was used as the solvent. Tablets were procured from the local market for assay and recovery studies.

Methods

Preparation of Standard Stock Solution

Acarbose standard stock solution was prepared by dissolving accurately weighed quantity of Acarbose (25mg) in 25 mL of methanol after proper sonication and poured in to 25mL of volumetric flask. Final volume was adjusted up to the 25mL mark using methanol for obtaining the standard stock solution, 1000μg/mL.

Determination of Area Under Curve

The Acarbose solution (24µg/mL) was prepared and scanned at the wavelength range of 200 to 230nm and the maximum absorption was found to be 216nm. Therefore, area between 214 to 218 nm was selected for the method development (Fig.2).

Linearity and Range

From the Acarbose stock solution, suitable aliquots were pipetted out into different 25 mL volumetric flasks and further dilutions were done with methanol to produce working standard solutions of Acarbose, 24,28,32,36, and 40μg/mL. The differences in Area Under Curve of Acarbose were measured in the area from 214 to 218 nm. The standard curve of the Acarbose drug was plotted. The range of concentration over which the drug demonstrated linearity was fixed as an analytical concentration range i.e. 24 to 40μg/mL for Acarbose. (Table 1 and Figure. 2 to 6)

Validation of Proposed Method

Estimation of Drug present in the Dosage Form: (Tablet Assay Study)Brand name- Glucobay®25 Standard: From the Acarbose standard stock solution, suitable aliquots were pipetted out into 25 mL volumetric flasks and serial dilutions were done with methanol to prepare working standard solution of Acarbose 24μg/mL. This concentration was subjected to a scan within area of 214 to 218nm.

Sample : Ten tablets of Glucobay®25 containing 25 mg of Acarbose were weighed and finally powdered with the help of a mortar. Each uncoated tablet contains 25 mg of Acarbose. A fraction of the powder sample of equivalent to 25 mg of Acarbose was taken into volumetric flask. Dilution was effected to get concentration of 24μg/mL. These solutions were scanned within area between 214 to 218nm (Table 2).

Accuracy (Recovery Study)

Recovery experiments were employed for the study of accuracy of the method. This study was effected out by mixing known weight of bulk sample to the tablet and recovery was carried out at three concentration levels,80, 100, and 120% of standard concentrations of Acarbose. Recovery studies samples were also kept ready according to the above stated method. For each recovery level, three samples were prepared. These sample solutions were analyzed and % recoveries were computed by using the formula:

% Recovery = Observed amount of compound in sample/ Amount of all compound present in sample × 100

The values for recovery studies are summarized in Table 3.

Precision

The inter day precision study was carried out by using four different samples of Acarbose. The intermediate precision of the method was evaluated using four different analysts in the same laboratory (Table 4).

Results and Discussion

The Acarbose standard solutions prepared in methanol were subjected to scanning from 200 to 230nm for area under curve method using UV-Visible spectrophotometer. The standard curve of Acarbose was found to be linear at therange of concentration 24 to 40μg/mL at area between 214 to 218nm.

Therefore, it was clear that determination of Acarbose can be carried out in the presence of methanol with no intervention of any interfering substance in pharmaceutical preparations. With the aim of determining the practical applicability of the presented method for the assessment of commercially available brands (Glucobay®25) of medicament formulations, the technique beats first used on bulk drugs in their sample as well as concentrations were estimated. Then the technique was subjected to the assay in marketed dosage forms and satisfactory results were attained within the proper limits as per the content of the label claim for Acarbose.

The newly developed method was validated as per the international guidelines and parameters. The novel method for the quantitative investigation of Acarbose was subjected to different validation parameters like specificity and selective determination in the presence of formulation additives and necessities, studied for parameters such as linearity and range at changed levels of concentrations and checking standards where the range of determination was optimized, accuracy was proved by recovery studies at different concentration levels, precision was established through inter-day precision studies, where the samples were subjected to changed conditions other than optimized parameters.

Conclusion

Based on the above practical based studies, it can be decided that Area under curve method by UV spectrophotometry is well developed for the estimation of Acarbose. The proposed method for the drug chosen was economical, precise, and accurate. The most significant qualities of spectrophotometric techniques are rapidity and simplicity.⁷ Results of each parameters ofvalidation demonstrate that these analytical procedures are appropriate for intended purpose and congregate with the criteria defined in ICHQ2A/B guidelines.⁸ The method is a best alternative to HPLC methods for custom analysis and accurate and superior than the zero order UV spectroscopic methods.

Conflict of Interest

The authors declare no conflict of interest.