Determination of (R)- and (S)-Disophyramide in human plasma using a chiral α1-acid glycoprotein column

The direct resolution and quantitation of (R)- and (S)-disopyramide, isolated from human plasma, was accomplished using a chiral α₁-acid glycoprotein column. A LiChrosorb RP-2 column (50 × 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, 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 μg/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.