Abstract
A high-performance liquid chromatographic procedure using fluorescence detection has been developed for the determination of prazosin in plasma. Propyl-hydroxybenzoate was used as the internal standard. The chromatography 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 wavelengths of 247 and 394 nm, respectively. The retention times for prazosin 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 to 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. Stability tests showed that prazosin is stable for at least 2 weeks in plasma after freezing. The minimum detectable concentration of prazosin by this method was 0.5 ng/ml. The sensitivity obtained should enable the use of this method in future bioequivalency and/or pharmacokinetic studies.