Haloperidol is the prototype of the butyrophenones and the one that has been studied the most. Haloperidol and droperi-dol, the two butyrophenones available in the United States, are well absorbed from the GI tract.83 First-pass metabolism in the liver reduces the bioavailability of haloperidol to approximately 60%. Haloperidol undergoes extensive metabolism including N-dealkylation, reduction, oxidation, and N-oxidation. Most of the metabolites of haloperidol are inactive. Hydroxyhaloperidol, the reduced (ketone) metabolite of haloperidol, is the only active metabolite and it is also subject to extensive hepatic metabolism (Fig. 13.7).83,95
Was this article helpful?