Stereospecific determinations of (+/- )-DU-124884 and its metabolites (+/- )-KC-9048 in human plasma by liquid...

(+)-DU-124884 is a 5-HT1-like receptor agonist under investigation for drug development. A sensitive, stereospecific LC method was developed for the analysis of (+)-DU-124884, its optical isomer (-)-DU-124884 and their N-dealkylated metabolites, (+/- )-KC-9048, in human plasma. A plasma sample was treated with triethylamine in methanol and the proteins were precipitated by acetonitrile. The supernatant was evaporated to dryness under nitrogen. The analytes and internal standard (acebutolol) formed diastereomers with (S)-(+)-1-(1-naphthyl)ethyl isocyanate immediately. The diastereomers formed were extracted into diethyl ether. They were completely resolved from each other and from matrix peaks on a Microsorb silica column with a mobile phase of methanol-chloroform-hexane (8:12:80, v/v/v) in a run time of 26 min. Detection was by fluorescence with excitation wavelength at 320 nm and emission wavelength at 440 nm. The linearity range is 0.1-200 ng ml-1 (r > 0.99). The limit of quantitation is 0.1 ng ml-1 and the detection limit is 0.02 ng ml-1 (signal-to-noise ratio = 3). The interday precision and accuracy of quality control samples were 5.5-7.6% RSD (relative standard deviation) and 0 to+4% bias for (+)-DU-124884, 5.5-7.9% RSD and 0 to +4% bias for (-)-DU-124884, 4.5-6.5% RSD and -7 to 0% bias for (+)-KC-9048 and 4.5-7.5% RSD and -7 to 0% bias for (-)-KC-9048. Consistent recovery from different lots of human plasma, parallelism of the method, stabilities of on-system, reinjection, bench-top, freeze-thaw cycles and sample storage were established.