A validated method for the determination of verapamil and norverapamil in human plasma

The aim of the study was to develop a simple and sensitive analytical metho d to determine verapamil (V) and its metabolite norverapamil (N) in human p lasma with use of an HPLC isocratic system with fluoresence detection, foll owing fast extraction of the investigated compounds. Extraction recovery wa s 92.12% and 89.58% for V and N, respectively. Internal standard in HPLC wa s propranolol. Its recovery was 82.50% on the average. Limit of detection w as 0.924 ng/ml and limit of determination was 3.080 ng/ml for V, what corre sponds concentration in plasma 1.232 ng/ml. For N limit of detection was 0. 030 ng/ml and limit of determination was 1.001 ng/ml what corresponds 0.4 n g/ml in plasma. Parameters of validation prove that precision of the presented method is ve ry good. The method is fast and one chromatogram separation lasts about 8 m inutes. 30-40 manual (without autosampler) analyses per day were done. It w as used successfully in pharmacokinetic and bioavailability studies of vera pamil administration in drug formulations alternative to tablets: buccal an d flotation ones. (C) 2001 Elsevier Science B.V. All rights reserved.