CHANGES IN THE BINDING-CAPACITY OF ALPHA-1-ACID GLYCOPROTEIN IN PATIENTS WITH RENAL-INSUFFICIENCY

The elevation of alpha-1-acid glycoprotein (AAG) concentration and the binding characteristics of disopyramide (DP) to AAG in patients with renal insufficiency were investigated. The serum AAG concentration and protein binding of DP in patients were significantly greater than tho se in healthy subjects. However, in both the serum and the purified AA G, Scatchard analysis showed that the number of binding sites per mole cule of AAG in patients was significantly lower than that in healthy s ubjects, although there was no difference in the dissociation constant (K-d). These results suggest that the AAG induced in renal insufficie ncy is qualitatively different from normal AAG. Moreover, the change o f the unbound DP fraction when DP concentration was increased was larg er in the patients than in the healthy controls. Therefore, monitoring of the unbound DP would be important for therapeutic drug monitoring in patients with renal insufficiency.