Simultaneous estimation of two anti-diabetic drugs; Linagliptin and empagliflozin in their tablet by chemometric spectrophotometry.

Four spectrophotometric approaches had been established and optimized for the simultaneous estimation of two anti-diabetic drugs; linagliptin (LIN) and empagliflozin (EMP) in their bulk and tablet dosage form. LIN concentration could be first determined from the zero order spectra at its λ_max (293 nm) without interference from EMP as at this wavelength EMP showed zero absorbance. The LIN and EMP zero order absorption spectra displayed considerable overlap which hindered the direct determination of EMP. Thus, four indirect spectrophotometric approaches were established and optimized for the determination and quantification of EMP concentrations in presence of LIN. Method (I) was ratio difference method (RD) which depended on the determination of difference amplitudes in the ratio spectra (ΔP) at 236 nm and 227 nm; ΔP_(236-227) was directly proportional to EMP concentration. Method (II) was ratio derivative method (¹DD) based on the measuring of the amplitude of first derivative of ratio spectra at 243 nm which was directly proportional to EMP concentration. For determination of EMP concentration using both method (I) and (II); LIN 7 µg/mL was used as the divisor. Method (III) was area under curve method (AUC) which depended on the measurement of area confined between 220 and 230 nm and 273-290 nm. Method (IV) was dual wavelength method (DWL) which based on measurement of absorbance difference (ΔA) in zero order spectra between 239.8 and 282.6 nm which was directly proportional to EMP concentration. The four developed methods were optimized and entirely validated regarding to ICH guidelines. The proposed spectrophotometric approaches were used for the quantification of LIN and EMP simultaneously in their tablet dosage form. F-test and t-test were applied for statistical comparison between the results obtained by the proposed approaches and that obtained by the reported method. There was no significant difference concerning to precision and accuracy.