[The effect of imipramine and trazodone on the re-uptake of (3H) serotonin by thrombocytes in patients with endogenous depression: changes in antidepressive therapy].

The inhibitory potencies of imipramine (IC50-values for IMI) and trazodone (IC50-values for TRA) on platelet [3H]serotonin uptake were measured in depressed patients. The IC50-values for IMI in patients was shown to be higher (P less than 0.01) than in controls. The IC50-values for TRA in patients were lower (P less than 0.01) than found in platelets from controls. These alterations were not accompanied by the significant decrease of a density of platelet [3H]imipramine binding sites. Drug treatment led to the normalization of the IC50-values for IMI and to the partial increase of the IC50-values for TRA. There was a negative correlation of IC50-values for TRA and severity of depressive symptoms evaluated by the Hamilton Depression Rating Scale. The results support the hypothesis that the mechanisms of the regulation of [3H]serotonin uptake sensitivity to IMI and TRA in patients are different.