Development and validation of a chiral capillary electrophoresis method for melagatran and ximelagatran drug substances

Abstract

This work presents the development and validation of an enantioselective capillary electrophoresis (CE) method for two new drug substances, the novel direct thrombin inhibitor melagatran and its oral prodrug ximelagatran. CE with a derivatised cyclodextrin as the chiral discriminant was examined as a viable alternative after failing to achieve sufficient selectivity and sensitivity using chiral liquid chromatography (LC). A robust and sensitive chiral method was developed which utilised a low pH phosphate buffer with heptakis(2,6-Di-O-methyl)-β-cyclodextrin to achieve chiral recognition for both drugs with additional organic modifier to fine tune selectivity. Quantitation at the 0.05% (w/w) level was achieved by employing sample stacking effects possible with a 200 mM phosphate buffer in combination with a narrow 50 μm ID capillary. A full validation was subsequently carried out according to the ICH guidelines, including selectivity, linearity, detection and quantitation limits, accuracy, precision, stability of analytical solutions, and robustness. Linearity, precision, and accuracy data were shown to be adequate over the entire range including at the 0.05% (w/w) quantitation limit. Several electrolyte parameters in addition to buffer depletion and cyclodextrin batch variations were amongst the parameters verified for method robustness.