Hepatic microsomal mixed-function oxidase system in rats pretreated with cicloxilic acid

In a study of the hepatic microsomal drug metabolising system in rats, pretreatment with cis-2-hydroxy-2-phenyl-cyclohexanecarboxilic acid (cicloxilic acid) did not prolong pentobarbital sleeping time or decrease the cytochrome P 450 content of the liver microsomes. The drug interacted with the liver microsomes to yield a type II spectral change. Cicloxilic acid did not affect the metabolism of CCl4 in vivo, as judged by the covalent binding of 14C from 14CCl r to microsomal lipids, or delay the gastrointestinal absorption of CCl4, as judged by the concentration of free CCl4 in the liver. The protection afforded by cicloxilic acid against CCl4 liver damage is therefore due neither to inhibition of the metabolism nor to delayed absorption of the toxin.