A QUANTITATIVE ANALYTICAL METHOD FOR THE DETERMINATION OF A NEW ANXIOLYTIC (CGS 19480A) IN HUMAN PLASMA USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A sensitive and specific analytical method has been developed for the determination of a new anxiolytic (CGS 19480A) in human plasma using h igh performance liquid chromatography (HPLC). The drug and internal st andard (CGS 18102A), were extracted with hexane at pH 7. Separations w ere achieved by reversed phase chromatography on a Nucleosil 5 C-18 co lumn at a flow rate of 1.0 mL/min. The mobile phase consisted of aceto nitrile: 0.01 M phosphate buffer (pH 7): methanol (51:35:14, v:v:v), w here the final pH of the mobile phase was adjusted to 4.0 using 85% ph osphoric acid. Plasma standard curves were linear from 5.0 to 500 ng/m l, with recovery of the drug being greater than 95% at all concentrati ons. 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 suc cessfully applied to the analysis of clinical samples from a single-do se safety and tolerability study conducted in six healthy male volunte ers.