APPLICATION OF MICELLAR ELECTROKINETIC CHROMATOGRAPHY TO THE QUALITY-CONTROL OF PHARMACEUTICAL FORMULATIONS - THE ANALYSIS OF XANTHINE DERIVATIVES

Micellar electrokinetic chromatography (MEKC) has been applied to the analysis of three different drugs. Although belonging to different therapeutic classes, all these drugs contain xanthine derivatives as active substances. Pentoxifylline was separated from eight related xanthines. Quantitative MEKC was applied to determine impurities (caffeine and xanthine) in the purified drug at the 0.05-0.1% level and also for the determination of the active substance in Agapurin(R) tablets. Ethofylline and theophylline were separated from ephedrine and mebrophenhydramine and determined in Xantedrylettae(R) tablets while caffeine was separated from mephenhydramine and determined in Kinedryl(R) tablets. In all cases, simple berate buffers with sodium dodecyl sulfate as the surfactant were satisfactory and little separation optimization was required. The relative standard deviation (RSD) of the migration times was better than 1% while the RSD of the observed areas was better than 2%. This demonstrates that MEKC is a valuable alternative for the traditional highperformance liquid chromatography analysis of drugs and drug formulations.