cis-(-)-Sertraline (aka 1R,4R-sertraline) is the therapeutically inactive enantiomer of Sertraline. Sertraline has four stereoisomers: (1R,4R), (1S,4S), (1R,4S), and (1S,4R), of which the (1S,4S) isomer is the active therapeutic compound. Sertraline is sold under the brand name Zoloft (and others) as an anti-depressant acting as a selective serotonin reuptake inhibitor. The bio-activity of sertraline is restricted to (1S,4S), and (1R,4R), where (1S,4S) is most potent.