Separation of alogliptin enantiomers in cyclodextrin-modified capillary electrophoresis: A validated method

The single enantiomer drug, alogliptin (Alo, Nesina®) is a novel, orally available and selective dipeptidyl peptidase‐4 inhibitor used for the treatment of type II diabetes. Following its pKa determination by CE‐pH titration, a validated chiral CE method has been developed to separate Alo enantiomers. Preliminary screening of the native CDs and their ten derivatives revealed that sulfopropylated‐γ‐CD, sulfopropylated‐β‐CD and sulfopropylated‐γ‐CD, sulfobutyl‐ether‐β‐CD (SBE‐β‐CD) and sulfobutyl‐ether‐γ‐CD enabled enantioresolution. Furthermore, cavity size dependent enantiomer migration order reversal was observed between γ‐ and β‐CD derivatives. To improve enantioseparation, buffer composition and pH, CD concentration, applied voltage, temperature, and injection parameters were optimized for the Alo/ SBE‐β‐CD system, yielding a resolution of 8.34. RSD percentage of the resolution value, migration times, and corrected peak areas were below 3 and 5% during testing repeatability and intermediate precision. LOD and LOQ values were found to be 2 and 6 μg/mL, respectively, for each enantiomer. Calibration lines ranging from 6 to 250 μg/mL were constructed with r2 > 0.9997. Robustness could be successfully verified by using the Plackett–Burman statistical experimental design. The optimized system containing 5 mM SBE‐β‐CD in a 25 mM acetate buffer at pH 4.75 was found promising to detect 0.1% distomer in the presence of the API.