Quantitation of Verapamil and Norverapamil in Small Blood Samples From the Rat by High Performance Liquid Chromatography

A simple, sensitive HPLC assay using flurescence detection was developed for quantitation of verapamil and its active metabolite, norverapamil in 100-200 l blood samples from the rat. Baseline separation of verapamil, normverapamil and internal standard, propranolol, was attained within 14 minutes. Standard curves for verapamil and norverapamil were linear from 7 ng/ml to 1000 ng/ml with limit of detection of 4 ng/ml for both Compounds. the intraday and interday coefficients of variation in verapamil and norverapamil concentrations, determined from spiked whole blood samples, were less than 10%.