Quantitative determination of heparinoid mimetics in human and rat plasma by micellar electrokinetic chromatography

The investigated new class of heparinoid mimetics are spaced persulfated carbohydrates designed to increase the success rate of angioplasty and bypass surgery by preventing restenosis without increasing the risk of bleeding. Due to the presence of sulfate groups, these compounds are highly charged and, for preclinical kinetic investigations only small sample volumes of rat plasma were available. Therefore, capillary electrophoresis (CE) was applied. A bioanalytical method based on micellar elektrokinetic chromatography (MEKC) with UV-detection was developed for the selective quantitation of heparinoid mimetics (e.g., Ro 48-0843, Ro 48-3151, Ro 47-6199 and Ro 48-8722) in plasma. Using this method, only small volumes of plasma were required, which could be introduced directly into the separation capillary after 1:1 dilution with 100 mM aqueous sodium dodecyl sulfate (SDS). For increased sample throughput, an additional ultrafiltration step was performed after SDS-dilution of the plasma sample, improving both reproducibility and robustness of the method considerably. The sensitivity of the new method (3 micrograms/ml) was sufficient to follow plasma levels in pharmacokinetic studies. The practicability of this easy and rapid assay was demonstrated by the analysis of more than 350 plasma samples from pharmacokinetic studies performed in rats.