title: Quantitative determination of verapamil and metabolites in human serum by high-performance liquid chromatography and its application to biopharmaceutic investigations.
abstract: A specific and sensitive high-performance liquid chromatographic method for the quantitative analysis of verapamil and N-desmethylverapamil in human serum is described. The analytes were extracted from serum using diethylether under alkaline conditions, followed by back extraction into dilute hydrochlorid acid for chromatographic analysis on a reversed-phase column with a mobile phase consisting of acetonitrile, water and perchloric acid at a flow rate of 1 l/min. The analytes were detected by fluorescence detection, the influence of temperature on retention is discussed. The method is linear, quantitative and reproducible for two calibration ranges in serum (2.5 ng/ml-100 ng/ml and 12.5 ng/ml-500 ng/ml) using peak area ratios analyte/internal standard for quantification. At ultimate sensitivity, concentrations down to 250 pg/ml could be assayed. The method was selective to 6 other metabolites of verapamil and common exogenous interferences. It was applicated to the serum samples of a comparative 120 mg - verapamil hydrochloride tablet single dose two-way cross-over study comprising 18 volunteers. The pharmacokinetic data for both formulations are presented.
authors.affiliation: LAB GmbH & Co, Neu-Ulm, Fed. Rep. of Germany.
authors.forename: Z B
authors.initials: ZB
authors.lastname: Salama
authors.forename: C
authors.initials: C
authors.lastname: Dilger
authors.forename: W
authors.initials: W
authors.lastname: Czogalla
authors.forename: R
authors.initials: R
authors.lastname: Otto
authors.forename: H
authors.initials: H
authors.lastname: Jaeger
mesh_terms: D001702:Biopharmaceutics; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D005711:Gallopamil / Q000097:blood; D006801:Humans; D007202:Indicators and Reagents; D014700:Verapamil / Q000031:analogs & derivatives / Q000097:blood* / Q000493:pharmacokinetics
chemical_list: D007202:Indicators and Reagents; D005711:Gallopamil; C016904:norverapamil; D014700:Verapamil