Stereoselective binding of disopyramide to human plasma protein

The binding of racemic disopyramide and its two enantiomers to protein were compared in two samples of human plasma, two samples of freshly drawn serum and in a solution of alpha 1-acid glycoprotein. The binding of S(+)-disopyramide was higher at all concentrations as compared to to R(-)-disopyramide, and the binding of the racemate was intermediate. Differences in binding were due to differences in the association constant.