Effect of Simultaneous Administration of Drugs on Absorption and Excretion. XIX. Binding of Acetohexamide and Its Major Metabolite, (-)-Hydroxyhexamide, to Human Serum Albumin

The binding of acetohexamide and its major metabolite, (-)-hydroxyhexamide, to human serum albumin (HSA) was examined by using the equilibrium dialysis method. (-)-Hydroxyhexamide was isolated from the urine of rabbits after oral administration of acetohexamide. The Scatchard plots suggested that acetohexamide interacts with two kinds of binding sites on HSA, whereas (-)-hydroxyhexamide interacts with only one kind of binding sites. In addition, the binding parameters obtained led us to conclude that serum protein binding of (-)-hydroxyhexamide is considerably lower than that of acetohexamide.