HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE QUANTITATIVE-DETERMINATION OF PHENIRAMINE IN PLASMA

A simple, sensitive and reproducible high performance liquid chromatog raphic (HPLC) method for the determination of pheniramine in plasma ha s been developed and validated. The assay is performed after single ex traction of pheniramine and amitriptyline (internal standard) from alk alinized plasma into ether. The drug and the internal standard were el uted from a mu-Bondapak C-18 column at 40 degrees C with a mobile phas e consisting of methanol: water (62:38%, v/v) adjusted with phosphoric acid to an apparent pH 3.5 at a flow rate of 1.2 ml/min. The effluent was monitored with an ultraviolet detector set at 262 nm. Standard cu rves for the analyte in plasma were linear (r>0.999) in the range of 2 0-400 ng/ml and the minimum detectable concentration in plasma is 10 n g/ml. The within-day coefficient of variation (CV) ranged from 3.57% t o 6.51% at three different concentrations, The between-day CVs varied from 5.03% to 7.84%. The absolute recoveries of pheniramine ranged fro m 94% to 96.9% and the relative recoveries ranged from 92% to 109.3% a t three different concentrations. Stability tests showed that pheniram ine is stable for at least 3 weeks in plasma after freezing. The metho d is applied for the determination of the pharmacokinetic parameters o f pheniramine after administration of a 75-mg tablet (Avil-retard) to six beagle dogs.