Inhibition of amine oxidases by the histamine-1 receptor antagonist hydroxyzine

Abstract

The effects of the drug hydroxyzine on the activities of the rat liver monoamine oxidases (EC 1.4.3.6; MAO) and the membrane-bound and soluble forms of bovine semicarbazide-sensitive amine oxidase (EC 1.4.3.6; SSAO) were studied. Hydroxyzine was found to be a competitive inhibitor of MAO-B (Ki ∼ 38 μM), whereas it had a low potency towards MAO-A (IC50 > 630 μM). Although it was a relatively potent competitive inhibitor of bovine plasma SSAO (Ki ∼ 1.5 μM), it was a weak inhibitor of the membrane-bound form of the enzyme from bovine lung (IC50 ∼ 1 mM). These findings extend our knowledge of the drug binding capabilities of the amine oxidases and suggest that these interactions may contribute to the complex actions of this drug. © Springer-Verlag 2006.