Spectrophotometric Determination of Megagliptin and its Assay by Charge - Transfer Method using 2,3-Dichloro- 5,6 -Dicyano-1,4- Benzoquinone (DDQ)

A simple, versatile and a new spectrophotometric method is proposed for the estimation of microgram quantities of the drug Megagliptin.  The drug forms a charge transfer (CT) complex with 2,3-Dichlro-5,6-Dicyano-1,4- Benzoquinone (DDQ), the stoichiometry of which is established as 1:1 by Job’s continuous variation method.   The wavelength of maximum absorbance of the CT complex is found to be 385 nm.  The absorbance values of the CT complex increased linearly with the increase in the amount of the drug Megagliptin upto 300 μg/ml.  This suggests that suitability of the method for the determination of the drug in the range 10 μg/ml to 300 μg/ml.  This also indicates the verification of the Beer-Lambert’s Law in this range.  The method is successfully applied to evaluate the assay of commercial tablets in pharmaceutical formulations for Megagliptin and the results agreed very well.  The molar absorptivity and Sandell Sensitivity of the method are 2.346 x 104  lit. mol-1. cm-1  and 0.01818 μg.ml-1.cm2 respectively.