Effects of perphenazine on imipramine metabolism in man.

In previous studies we have shown that perphenazine inhibits the metabolism of nortriptyline and imipramine. In this study the metabolism of 14C-imipramine and 14C-desipramine was studied before and during treatment with perphenazine. Studies on the imipramine and desipramine metabolites in urine showed that the major effect of perphenazine is an inhibition of the 2-hydroxylation of imipramine and desipramine. This causes a decreased formation and excretion of non-conjugated and glucuronide bound hydroxy metabolites and accumulation of imipramine and desipramine. There was some relationship between the dose of perphenazine and the decrease in total urinary excretion but the individual variations in response were pronounced (2-3-fold).