SIMULTANEOUS LIQUID-CHROMATOGRAPHIC DETERMINATION OF 3 ANTI-ARRHYTHMIC DRUGS - DISOPYRAMIDE, LIDOCAINE, AND QUINIDINE

Abstract

A common methodology was reported for determining 3 antiarrhythmic drugs: disopyramide, lidocaine and quinidine. Alkalinized human serum and internal standard (p-chlorodisopyramide) are extracted into dichloromethane, the organic phase is evaporated and the redissolved residue is injected onto a reversed-phase column (.mu. Bondapack C18). Quantitation is via peak-height ratios of analyte vs. internal standard (as detected at 205 nm) referenced to a serum-based multiple-drug standard. A mobile phase of 30 mmol/l phosphate buffer and acetonitrile (72/28 by vol) is used. These conditions yield optimum separation and band symmetry for the analytes and some of their metabolites. Crucial factors in this simultaneous assay include pH of the mobile phase and injected solution, extraction time and evaporation technique. Day-to-day precision (CV) for all drugs was < 5%, and correlation with other assay techniques for each drug is reported. The method enables more efficient use of personnel and instrumentation without sacrificing analytical quality.