Analytical Enantio-Separation of Linagliptin in Linagliptin and Metformin HCl Dosage Forms by Applying Two-Level Factorial Design.

A novel, stability indicating, reverse phase high-performance liquid chromatography (RP-HPLC) method was developed to determine the -isomer of linagliptin (LGP) in linagliptin and metformin hydrochloride (MET HCl) tablets (LGP-MET HCl) by implementing design of experiment (DoE), i.e., two-level, full factorial design (2³ + 3 centre points = 11 experiments) to understand the critical method parameters (CMP) and its relation with the critical method attribute (CMA), and to ensure robustness of the method. The separation of the -isomer, LGP and MET HCl in the presence of their impurities was achieved on Chiralpak IA-3 (), immobilized on 3 µm silica gel) stationary phase (250 × 4.6 mm, 3 µm) using isocratic elution and detector wavelength at 225 nm with a flow rate of 0.5 mL·min, an injection volume of 10 µL with a sample cooler (5 °C) and column oven temperature of 25 °C. Ethanol:Methanol:Monoethanolamine (EtOH:MeOH:MEA) in the ratio of 60:40:0.2 // was used as a mobile phase. The developed method was validated in accordance with international council for harmonisation (ICH) guidelines and was applied for the estimation of the -isomer of LGP in LGP-MET HCl tablets. The same method also can be extended for the estimation of the -isomer in LGP dosage forms.