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 the rapeutic classes, all these drugs contain xanthine derivatives as acti ve substances. Pentoxifylline was separated from eight related xanthin es. Quantitative MEKC was applied to determine impurities (caffeine an d xanthine) in the purified drug at the 0.05-0.1% level and also for t he determination of the active substance in Agapurin(R) tablets. Ethof ylline and theophylline were separated from ephedrine and mebrophenhyd ramine 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 r equired. 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 tra ditional highperformance liquid chromatography analysis of drugs and d rug formulations.