Evidence for binding of certain acidic drugs to alpha 1-acid glycoprotein.

The binding of some acidic drugs to alpha 1-AGP was studied by equilibrium dialysis at 37 degrees, pH 7.4. Certain acidic drugs bound to alpha 1-AGP at one binding site with a high affinity. Though the alpha 1-AGP plasma concentration is far lower than the HSA concentration, the association constants of some acidic drugs with alpha 1-AGP are high enough to suggest that binding to alpha 1-AGP will contribute significantly to the total plasma binding of these drugs.