A quantitative analytical method for the determination of a new anxiolytic (CGS 19480A) in human plasma using high...

A sensitive and specific analytical method has been developed for the determination of a new anxiolytic (CGS 19480A) in human plasma using high performance liquid chromatography (HPLC). The drug and internal standard (CGS 18102A), were extracted with hexane at pH 7. Separations were achieved by reversed phase chromatography on a Nucleosil 5 C18 column at a flow rate of 1.0 mL/min. The mobile phase consisted of acetonitrile: 0.01 M phosphate buffer (pH 7): methanol (51:35:14, v:v:v), where the final pH of the mobile phase was adjusted to 4.0 using 85% phosphoric acid. Plasma standard curves were linear from 5.0 to 500 ng/ml, with recovery of the drug being greater than 95% at all concentrations. The method was validated over a concentration range of 5.0 to 500 ng/mL with a limit of quantification of 5.0 ng/mL. The method was successfully applied to the analysis of clinical samples from a single-dose safety and tolerability study conducted in six healthy male volunteers.