Sensitive high-pressure liquid chromatographic determination of disopyramide and mono-N-dealkyldisopyramide

A high-pressure liquid chromatographic procedure for the accurate determination of disopyramide and its chief metabolite in plasma is presented. The method is suitable for monitoring patients receiving disopyramide therapy. A reversed-phase cyanopropylsilane column is utilized with a mobile phase of 50% acetonitrile and 50% 0.01 M sodium acetate buffer at pH 4.0. Absorption was monitored at 254 nm with a detection limit of 0.2 microgram/ml of plasma. The reproducibility and precision of the procedure were demonstrated on samples containing 0.50-12 microgram/ml of plasma.