Binding of disopyramide to alpha 1-acid glycoprotein in plasma measured by competitive equilibrium dialysis.

A modification of equilibrium dialysis in which alpha 1-acid glycoprotein and plasma compete directly for disopyramide has been used in conjunction with binding curves to measure the extent of the alpha 1-acid glycoprotein-disopyramide interaction. At concentrations in the therapeutic range, 80-90% of disopyramide was bound to alpha 1-acid glycoprotein for plasma from each of six healthy adults. Also, equilibrium dialysis data are presented, indicating that pH does not influence the binding of disopyramide within the therapeutic range.