Vortioxetine-d8 is intended for use as an internal standard for the quantification of vortioxetine (Item No. 23694) by GC- or LC-MS. Vortioxetine is a multimodal serotonergic agent that acts as a serotonin (5-HT; Item No. 14332) reuptake inhibitor (Ki = 1.6 nM) and binds to the 5-HT1A, 5-HT1B, 5-HT3A, and 5-HT7 receptors (Kis = 15, 33, 3.7, and 19 nM, respectively).1 It also binds to the β1-adrenergic receptor (Ki = 46 nM). It acts as an antagonist at 5-HT3A and 5-HT7, a partial agonist at 5-HT1B, and a full agonist at 5-HT1A receptors. Vortioxetine is selective for the serotonin transporter (SERT) over the dopamine and norepinephrine transporters (IC50s = 5.3, 890, and 140 nM, respectively). It has affinity for histamine H2, melanocortin 4, β2-adrenergic, 5-HT2C, and 5-HT6 receptors with Ki values greater than 180 nM, but it is selective over the majority of targets in a panel of 75 ion channels, G protein-coupled receptors, enzymes, and transporters. Vortioxetine (5 or 10 mg/kg per day) increases 5-HT levels in vivo in rat brain and decreases occupancy at SERT. At acute and chronic doses of 5 mg/kg, but not 10 mg/kg, it increases the time mice spend in the center of the open field test, increases mobility in the forced swim test, and decreases the latency to feed in the novelty suppressed feeding test.2 It also increases proliferation and survival of adult-born granule cells in the hippocampus. Formulations containing vortioxetine have been used in the treatment of major depressive disorder.WARNING This product is not for human or veterinary use.