Liquid chromatography in the monitoring of plasma levels of antiarrhythmic drugs.

High-performance liquid chromatography has been employed in the development of assay methods for six antiarrhythmic drugs, disopyramide, lidocain, tocainide, procainamide, aprinidine and quinidine. Liquid-solid chromatography has been used and separation times of about 5 min have usually been sufficient. Owing to the capacity of the liquid chromatographic system, sample preparation has been minimized to a single extraction and direct injection of a considerable part of the extract. The overall time of analysis is very short and the methods are well suited for monitoring of plasma levels of the antirrhythmic drugs and in some instances (procainamide and disopyramide) also for their main metabolites. UV detection at the optimal wavelength has permitted determinations down to 50 pmole (20 ng) in 1 ml of plasma for the amines with high absorbance.