Levomilnacipran-d 10 ((1S,2R)-Milnacipran-d 10 ) hydrochloride is deuterium labeled Levomilnacipran. Levomilnacipran (F2696; (1R,2S)-milnacipran), an enantiomer of milnacipran, is a selective serotonin and norepinephrine (5-HT/NE) reuptake inhibitor. Levomilnacipran also is a human alpha-adrenergic receptor antagonist, with an IC 50 of 3.4 μM. (patent WO2013014263A1).