[Binding and distribution of chlordiazepoxide (Radepur) and its metabolites in the erythrocyte-plasma and erythrocyte-buffer systems].

The distribution and the free concentration of chlorodiazepoxide, desmethyl-chlorodiazeoxide and demoxepam in the systems erythrocyte-plasma and erythrocyte-buffer is determined. In both systems the substances are bound by erythrocytes. A constant ratio of distribution between erythyrocyte-plasma and erythrocyte-buffer, respectively, is established beyond therapeutic concentrations. The association constants (dual reciprocal plot) of these substances are of the order of 10(4)-1-M-1. They are the same for erythrocytes and plasma. The specific binding of erythrocytes is 20-35 fold less than with plasma proteins. It is concluded that the erythrocytes are a binding intravascular subcompartment for chlorodiazepoxide and its metabolites.