A sensitive high-performance liquid chromatographic analysis of propranolol in serum

A rapid and sensitive high-performance liquid chromatographic (HPLC) assay was developed for quantitative determination of propranolol in serum. The assay is performed after single extraction of propranolol and indenolol [internal standard (IS)] from alkalinized serum into ether and eluted from C-18 U Bondapak column with a mobile phase composed of methanol: 0.01 M phosphate buffer pH 3.4 (40:60%, v/v). The column eluant was monitored on a fluorescence detector. Measurement was achieved by taking the peak height ratio of propranolol and comparing it to that of the IS. The detection limit for propranolol in serum is 2.5 ng/ml. Intraday coefficients of variation (CV) ranged from 2.84 to 4.0% and interday (CVs) from 5.8 to 8.4% at three different concentrations. The relative and absolute recoveries varied from 93.8 to 102.3%. Preliminary stability tests showed that propranolol is stable for at least 3 weeks in serum after freezing. The method is applied for the determination of the pharmacokinetic parameters of propranolol after intravenous administration (1 mg/kg) to rabbits.