Binding of minaprine to human serum proteins and erythrocytes

The binding of minaprine to human serum, isolated proteins and erythrocytes was studied in vitro. This drug shows both a saturable and a nonsaturable binding process in serum. The drug is bound to alpha 1-acid glycoprotein in a saturable fashion with a moderate affinity whereas albumin is involved in the nonsaturable and major binding. The combination of these two processes results in a slight decrease (7%) in the drug binding to serum within the range of therapeutic concentrations. Competitive binding with metabolites of minaprine or with other basic drugs seems unlikely when these compounds are present in serum at therapeutic levels. The binding of minaprine to erythrocytes remains constant within the range of therapeutic concentrations.