Quality-by-Design Approach for Chromatographic Analysis of Metformin, Empagliflozin and Linagliptin

New analytical quality by design-oriented HPLC method with multiple response optimization (Derringer's desirability function) was demonstrated for simultaneous analysis of three antidiabetic drugs (metformin hydrochloride/empagliflozin/linagliptin) in a fixed-dose combination. Central composite design was employed for systematic optimization of critical method parameters, namely, % organic phase (X1), aqueous phase pH (X2) and flow rate (X3) while resolution, capacity factor and theoretical plate number as critical analytical attributes. Effective chromatographic separation of title analytes was accomplished on Std. Discovery C18 column at 30°C with mobile phase comprising acetonitrile: phosphate buffer pH 5 (38:62% v/v), pumped at a flow rate of 1 mL/min by isocratic elution pattern and UV detection at 222 nm. The model is rectilinear in the range of 1.0-200, 0.2-40 and 0.1-20 μg/mL at retention times of 3.04, 3.93 and 5.99 min for metformin, empagliflozin and linagliptin, respectively. The method obeyed all validation parameters of ICH Q2(R1) guidelines. The proposed HPLC method was highly robust for method transfer, regulatory flexibility within design space and can be used for assay of pharmaceutical dosage forms comprising these analytes. The proposed method was applied for stability studies of drugs under various stress conditions.