ANALYSIS OF PRAZOSIN IN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY USING FLUORESCENCE DETECTION

A high-performance liquid chromatographic procedure using fluorescence detection has been developed for the determination of prazosin in pla sma. Propyl-hydroxybenzoate was used as the internal standard. The chr omatography was performed using adsorbsphere phenyl column; the mobile phase consisted of 30:70% acetonitrile to 0.05 M phosphate buffer and was adjusted to pH 3.3-3.4 using phosphoric acid; a flow rate of 1.5 ml/min; and the effluent was monitored at excitation and emission wave lengths of 247 and 394 nm, respectively. The retention times for prazo sin and the internal standard were 4.0 and 6.0 min., respectively. The intraday coefficients of variation (CV) ranged from 1.15 to 4.96% at three different concentrations and the interday CVs varied from 0.05 t o 8.99%. The mean (+/- SD) absolute and relative recovery of prazosin were found to be 97.4+/-3.14 and 100.68+/-2.19, respectively. Stabilit y tests showed that prazosin is stable for at least 2 weeks in plasma after freezing. The minimum detectable concentration of prazosin by th is method was 0.5 ng/ml. The sensitivity obtained should enable the us e of this method in future bioequivalency and/or pharmacokinetic studi es.