Two Compartment Analysis of Plasma Elimination of Phenazone in Normals and in Patients with Cirrhosis of the Liver

Abstract The elimination kinetics of phenazone (NFN) after intravenous injection was investigated in seven healthy volunteers and in five patients with chronic liver disease. The plasma concentration/time data of phenazone were analysed according to a one compartment linear model and a two compartment linear open model, respectively. The elimination rate constant, the volume of distribution, and the clearance estimated by the one compartment model analysis correlated significantly with the corresponding parameters of the two compartment model analysis (r = +0.892, r = +0.989 and r = +0.999, respectively). The initial disposition constant (α) and the rates of distribution of phenazone between the central and peripheral compartment, k₁₂ and k₂₁ were unaltered in the patients with liver disease, whereas the clearance was significantly reduced. These results confirm that the plasma clearance of phenazone is reliably investigated by sampling only from the terminal phase of the plasma elimination curve.