DEMONSTRATION OF CLOMIPRAMINE AND VENLAFAXINE OCCUPATION AT SEROTONINREUPTAKE SITES IN MAN IN-VIVO

We describe the use of (CRTI)-C-11-55 and the Multiple Objects Coincid ences Counter (MOCC) to detect in-vivo binding to peripheral serotonin reuptake sites (left chest comprising platelet and lung serotonin reu ptake sites) in man. Displacement and preloading experiments with clom ipramine and venlafaxine in two healthy volunteers demonstrated that ( CRTI)-C-11-55 binding is decreased in a dose-dependent fashion by both these drugs which bind to the serotonin transporter. In addition para llel data from the total head curve (representing (CRTI)-C-11-55 bindi ng to central serotonin and dopamine (DA) reuptake sites) suggest that prior blockade of the serotonin transporter may be a useful strategy to maximize radioactive counts in the head when measuring the DA trans porter. The MOCC is likely to be useful to determine sequential indice s of relative serotonin reuptake blockade in patients on treatment.