Serotonin reuptake inhibition vs. norepinephrine reuptake inhibition: a double-blind differential-therapeutic study with fluvoxamine and oxaprotiline in endogenous and neurotic depressives.

The antidepressive properties of the specific serotonin reuptake inhibitor fluvoxamine and the specific norepinephrine reuptake inhibitor oxaprotiline were investigated in a sequential design with the aim of evaluating the hypothesis that two distinct biochemical subtypes of depression exist. Responders were treated for 7 weeks with the compound to which they had responded. After 1 placebo week, the nonresponders were switched to the alternative compound. An evaluation of the data obtained during the 3-week treatment periods from 24 patients (37 trials) with major depression revealed a highly significant reduction of Hamilton Scores with both compounds, oxaprotiline and fluvoxamine. If the patients with major depression are subdivided into two groups, endogenous depressives and neurotic depressives, there is no significant difference between the therapeutic improvements (both compounds) achieved in the two groups. The data shows that only about 20% of the nonresponders on one compound responded to the alternative drug, whereas 90% of responders (within 3 weeks) were still responders after 7 weeks. The data are at variance with the concept of two distinct biochemical subtypes of depression (serotonergic vs. norepinephrinergic). Dexamethasone suppression tests, performed in 23 patients, gave no prognostic hint as to whether the patients reacted well to drug therapy or not.