| Abstract: | This paper describes the protein binding of propisomide to human serum and isolated proteins using equilibrium dialysis. The drug is exclusively bound to alpha1-acid glycoprotein with high affinity. The binding is saturable even at low concentrations of the drug. Thus, the fraction unbound varied from 0.05 to 0.60 with decreasing serum concentration. The major metabolite of the drug or other drugs with affinity for alpha1-acid glycoprotein can displace propisomide from its binding site only when present in serum at high levels. Two ultrafiltration techniques are compared to equilibrium dialysis for the determination of serum protein binding of propisomide. Ultrafiltration does not give reliable results. Equilibrium dialysis is retained as an accurate method for the determination of the fraction unbound of propisomide. |
