Determination of (R)- and (S)-disopyramide in human plasma using a chiral alpha 1-acid glycoprotein column

The direct resolution and quantitation of (R)- and (S)-disopyramide, isolated from human plasma, was accomplished using a chiral alpha 1-acid glycoprotein column. A LiChrosorb RP-2 column (50 X 3.0 mm I.D.) was used as a precolumn. Phosphate buffer, pH 6.20, containing 2-propanol and N,N-dimethyloctylamine was used as mobile phase. The precision of the determination of (R)- and (S)-disopyramide in human plasma, expressed as the relative standard deviation, was 1.8% and 3.3% for (R)- and (S)-disopyramide, respectively, at a drug level of 0.5 micrograms/ml. In two subjects who received a single capsule of racemic disopyramide (150 mg), the plasma levels of the (R) isomer were about half those of the (S) isomer. The half-lives of (R)- and (S)-disopyramide were similar.