Lu-AA21004, an oral, multimodal serotonergic agent, is currently under 
development by H Lundbeck and Takeda Pharmaceutical, for the potential treatment 
of depression and anxiety. Lu-AA21004 belongs to a novel chemical class of 
antidepressant agents, the bisarylsulfanyl amines, and possesses a novel 
pharmacological profile, with activity at serotonergic receptors 5-HT3, 5-HT7 
and 5-HT1A, and also at the 5-HT transporter. Acute administration of Lu-AA21004 
in rats inhibited the firing activity of serotonergic neurons of the dorsal 
raphe nucleus through 5-HT3 receptor blockade, with rapid recovery of firing 
activity upon cessation of treatment compared with an antidepressant of the SSRI 
class. Results from phase II clinical trials have reported improvement in 
depression and anxiety symptoms after 6 weeks of treatment. Lu-AA21004 was 
generally well tolerated, with adverse events related to sexual dysfunction 
occurring in a lower number of patients receiving Lu-AA21004 compared with 
venlafaxine. Phase III clinical trials with Lu-AA21004 in patients with major 
depressive disorder are underway and phase III trials in patients with 
generalized anxiety disorder have been completed. If initial outcomes from these 
clinical trials prove positive, Lu-AA21004 may pave the way for new multimodal 
therapies for the treatment of depression and anxiety.