A double-blind comparison of zimelidine and desipramine in endogenous depression.

Zimelidine, a specific 5HT uptake inhibitor (final dose 225 mg), and desipramine, mainly a noradrenaline uptake inhibitor (final dose 150 mg), were given in random order to 24 in- and out-patients fulfilling the Research Diagnostic Criteria for Major Depressive Disorder, definite or probable endogenous type, for a 3-week treatment period. Nonresponders were crossed over to the other drug for another 3 weeks. There was a nonsignificant trend towards more overall improvement on desipramine. Some patients in both groups showed very little change during 3 weeks, indicating a bimodal distribution of response to either drug. Several nonresponders improved markedly upon direct crossing over to the other drug. There were few and mild side effects on both drugs, with no significant difference between them. No significant correlation was found between improvement and plasma concentrations of zimelidine, norzimelidine, or desipramine, whereas a significant positive correlation was found between improvement and platelet serotonin uptake inhibition (measured in fresh platelets incubated in diluted plasma from the patients) in zimelidine-treated patients.