Plasma 3,4-dihydroxyphenylethyleneglycol and therapeutic response to maprotiline and indalpine in major depression

Plasma levels of free and conjugated 3,4-dihydroxyphenylethyleneglycol (DOPEG), the main deaminated metabolite of norepinephrine, were assayed in 48 depressed patients before initiating a treatment with either maprotiline, an inhibitor of norepinephrine reuptake, or indalpine, a specific inhibitor of serotonin reuptake. The two groups of depressed patients were comparable. The therapeutic effect was evaluated by using the Hamilton Rating Scale for Depression. No difference in pretreatment plasma free and conjugated DOPEG levels was found between the responders and the nonresponders to maprotiline or indalpine. Neither was there any difference in the pretreatment levels of plasma free DOPEG between the two groups of responders and the two groups of nonresponders to either drug. Finally, there was no difference in the therapeutic response to maprotiline or to indalpine between the patients with high and low plasma DOPEG levels before treatment. These results indicate that there is no relationship between the initial plasma levels of DOPEG in depressed patients and their therapeutic response to a norepinephrine or a serotonin reuptake blocker.