Reduction of whole blood serotonin in depressed patients treated with a new, selective serotonin-uptake inhibitor, femoxetine.

Femoxetine, a phenylpiperidine derivative with potent serotonin (5-HT)-uptake inhibitory properties, was investigated in 12 depressive patients for its clinical effect as well as its effect on 5-HT concentration in whole blood. The global evaluation after 6 weeks showed a good effect in six patients. The 5-HT concentration was found to be reduced from a mean value of 0.21 to about 0.05 micrograms/ml, indicating a total depletion of 5-HT from the thrombocytes. The steady-state concentrations of femoxetine resulted in reduction of 5-HT to the same level in all patients. No correlation between degree of 5-HT reduction and therapeutic effect was found.