Sequential catecholamine and serotonin depletion in mirtazapine-treated depressed patients.

This study was aimed at determining whether patient- or antidepressant-related variables are most important to the mood response to serotonin (5-HT) or catecholamine depletion. Depressed patients treated with open-label mirtazapine (>or=6 wk) received two depletion tests (5-HT and catecholamine depletion) 1 wk apart. Both 5-HT and catecholamine depletion led to a partial return of depression in most patients. Antidepressant response to mirtazapine is dependent on its dual actions on norepinephrine and 5-HT neurotransmission. Mood response to tryptophan or catecholamine depletion is dependent on the pharmacological properties of the antidepressant being taken during depletion.