1974 年 94 巻 5 号 p. 602-606
A new method which can predict the in vivo binding ratio from the in vitro data is proposed. The binding of sulfisomidine with bovine serum albumin was examined using the ultrafiltration method, and the binding constant (K) and the maximum binding number (n) for sulfisomidine were found to be independent of the protein concentration. The values of n and K in the diluted sera obtained from 20 patients with chronic rheumarthritis were measured in vitro using the equilibrium dialysis method. From these data, the in vivo binding ratio at any plasma concentration of sulfisomidine was calculated theoreti-cally without using large quantities of samples. It was noticed that the higher the plasma concentration of the drug became, the more remarkable the individual variations were. This new method seems to be very useful for the comparative study of the human drug-protein binding.