Vilazodone Hydrochloride (EMD 68843 Hydrochloride) is a serotonin transporter (SER) inhibitor and 5-HT_1A receptor partial agonist. IC50 & Target: SER; 5-HT_1A^[1]. In Vivo: Administration of 5-HT_1A receptor agonists produce a characteristic behavioral syndrome that includes changes in posture, hind limb reduction, head weaving, tremors, forepaw treading, and straub tail. In the rat ultrasonic vocalizations test, stress-induced vocalizations are inhibited by Vilazodone Hydrochloride (EMD 68843 Hydrochloride) (55 mg/kg po) at 120 and 210 min post dose. Vilazodone Hydrochloride (EMD 68843 Hydrochloride) (20-40 mg/kg ip), administered acutely or prophylactically (1 week prior to behavioral testing), attenuated stress induces potentiated startle but has no effect on stress potentiated anxiety response in the elevated plus maze. Interestingly, a lower dose of 10 mg/kg of Vilazodone Hydrochloride (EMD 68843 Hydrochloride) has the opposite effect in the startle response, indicating a somewhat unexplained bidirectional effect, and all doses produce a potentiation of the startle-induced stress response possibly suggestive of an anxiogenic-like response^[1]. Vilazodone Hydrochloride (EMD 68843 Hydrochloride) also represents another option for the treatment of MDD^[2].