MCN-5652W68 is pharmacologically inactive enantiomer of an selective serotonin reuptake MCN-5652. The enantiomers of McN-5652 differed in their ability to inhibit ex vivo binding of paroxetine in rat frontal cortex and hypothalamus, in vitro uptake of 5-HT in rat blood platelets, and 5-HT-induced contraction of rat vascular smooth muscle, with (+)-McN-5652-Z being most active. No difference was observed between the effects of (+)- and (-)-McN-5652-Z on 5-HT metabolism by rat brain monoamine oxidase. MCN-5652, as enantiomeric mixture, is currently being used for positron emission tomography studies.