Determination of the dihydropyridine aryloxypropanolamine compound Z6568 and four metabolites in plasma by liquid chromatography/negative-ion mass spectrometry.

A sensitive and selective liquid chromatographic/mass spectrometric assay for the determination of the dihydropyridine aryloxypropanolamine compound Z6568 and four metabolites in plasma was developed and validated. Z6568 and the metabolites were isolated from plasma by a simple solvent extraction procedure and separated by reversed-phase high-speed liquid chromatography combined with thermospray mass spectrometry. Filament ionization was used and the molecular negative ions were monitored. The analysis of spiked plasma demonstrated the good accuracy and precision of the assay with a detection limit of 0.5 ng ml-1 for Z6568. Data relative to the optimization of the mass spectrometric conditions and the validation protocol are reported. the method has been used for pharmacokinetic studies in laboratory animals.