The Influence of Enterohepatic Circulation on Toxicity of Drugs*

Review of the Toxicology of Chlorpyrifos With an Emphasis on Human Exposure and Neurodevelopment

“…Based on molecular weight considerations and findings for comparable compounds, the glutathione and glucuronic acid conjugates identified earlier would be expected to be excreted to a significant extent in the bile in rats (Hirom et al, 1972). In the rat intestine microbial action is likely to cleave the conjugates (Williams et al, 1965). In the case of the glutathione conjugate this would result in a cysteine conjugate.…”

“…Neither the parent compound nor chlorpyrifos-oxon was detected in the urine in this subject. Some species differences in the urinary profile of metabolites between humans and rats may be expected because the molecular weight threshold in much lower in rats (around 300-350) than in humans (approximately 550) (Williams et al, 1965).…”

Phenobarbital-digitoxin interaction in the Guinea pig liver

“…The reduction of bile total concentration could also be explained by an alteration in the transport into the bile capillaries (17). Levine and Synge (18) studying the relation between the hepatic intracellular distribution «in vivo» and «in vitro» and the biliary excretion of several compounds showed that the subcellular distribution is dependent on the physicochemical properties of the compounds rather than on specific transport systems.…”

A Preliminary Study of the Absorption, Metabolism and Excretion of Injectable Thiambutosine

“…If biliary excretion of thiambutosine or its metabolites had been responsible fo r the discrepancy between the amoun t of thiam bu tosi ne in j ec ted and the p-dime thylaminodiphenyl thioureas excreted in the urine, the biliary excretion of thiambutosine and its metabolites would have averaged over 1 70 mg/day during the whole six months period. Williams, Millburn and Smith (1965) studied the biliary excretion of a number offoreign com pounds in the rat and showed that the com pounds excreted to the greatest extent in the bile were polar conjugates oflarge molecules. Thiam butosine was not excreted unchanged in the bile but as two metabolites which appeared to be glucuronides.…”