Clinical correlates of tricyclic antidepressant-mediated inhibition of platelet monoamine oxidase.

Previous reports suggest that tricyclic antidepressants inhibit platelet monoamine oxidase (MAO) activity in vitro and in vivo. This study was undertaken to examine the relationship between tricyclic-mediated inhibition of platelet MAO and resolution of clinical signs and symptoms which are commonly associated with the depressive syndrome. The results indicate that the sedative-hypnotic effects of the tricyclics closely correlate with the magnitude of platelet MAO inhibition. It appears that these effects may be mediated through alterations in the metabolism of serotonin and/or the phenylethylamines.