Plasma protein binding of imipramine in patients with rheumatoid arthritis

Summary In 23 patients with rheumatoid arthritis the plasma protein binding of³H-imipramine and the plasma levels of 13 proteins were measured in order to examine the significance of the proteins for the binding of imipramine. The degree of³H-imipramine binding did not differ significantly from that in healthy controls. It was positively correlated with the concentrations of fibrinogen, ₁-acid-glycoprotein, ceruloplasmin, complement C3_c, haptoglobin and hemopexin. Erythrocyte sedimentation rate was also highly positively correlated with binding. The concentration of several of the proteins showed a significant covariation. The³H-imipramine binding was negatively correlated with the concentration of albumin and the latter was negatively correlated with some of the proteins mentioned-above. No correlation with the levels of apolipoproteins A and B was found. There appears to be more a qualitative than a quantitative change in³H-imipramine binding in patients with rheumatoid arthritis.