The influence of physicochemical parameters on the biliary excretion of a series of nitroimidazoles

The relationship between physicochemical parameters and biliary excretion of nitroimidazoles was investigated. The unmetabolized form of each drug was detected in the bile by means of a UV procedure. A highly significant reversed parabolic relationship was shown between the Rmvalues and the biliary excretion of the test compounds. In other words, the compounds closer to the optimal Rmvalue are excreted less than those characterized by higher or lower Rmvalues. Since the Rmvalues seem to account for both the lipophilic and polar character of nitroimidazoles, the reversed parabola could be due to plasma protein binding and/or some protein binding within the hepatocyte. In fact, both the lipophilic and polar character seem to play an important role in protein binding of chemicals. © 1987, American Chemical Society. All rights reserved.