Abstract
A simple, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the determination of pheniramine in plasma has been developed and validated. The assay is performed after single extraction of pheniramine and amitriptyline - (internal standard) from alkalinized plasma into ether. The drug and the internal standard were eluted from a μ-Bondapak C
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column at 40°C with a mobile phase 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 curves for the analyte in plasma were linear (r>0.999) in the range of 20-400 ng/ml and the minimum detectable concentration in plasma is 10 ng/ml. The within-day coefficient of variation (CV) ranged from 3.57% to 6.51% at three different concentrations. The between-day CVs varied from 5.03% to 7.84%. The absolute recoveries of pheniramine ranged from 94% to 96.9% and the relative recoveries ranged from 92% to 109.3% at three different concentrations. Stability tests showed that pheniramine is stable for at least 3 weeks in plasma after freezing. The method is applied for the determination of the pharmacokinetic parameters of pheniramine after administration of a 75-mg tablet (Avil-retard) to six beagle dogs.