Rapid gas-liquid chromatographic method for plasma verapamil level determination.

Verapamil is a newly marketed antiarrhythmic drug. It has a significant presystemic elimination when administered orally and, therefore, intravenous therapy is often recommended. Optimum therapeutic effect is obtained when verapamil plasma concentrations are between 100 and 400 ng/ml. Several chromatographic procedures for the determination of verapamil in biological fluids have been described in the literature [l-11]. Some of the procedures have also quantitated verapamil metabolites [l, 6, 7 1. The highperformance liquid chromatographic (HPLC), as well as the gas-liquid chromatographic (GLC) procedures are sensitive but require lengthy and tedious multiple extraction steps especially when the metabolites are quantitated. This report describes a rapid, sensitive and accurate GLC procedure with thermionic specific detection for the determination of verapamil in dog plasma. This procedure also has a potential use in controlled clinical pharmacokinetic studies of this antiarrhythmic agent in humans.