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 r(2) > 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.