Antidepressant Vilazodone Superior to Placebo, Plus No Sexual Side Effects
Vilazodone (Viibryd) was approved by the Federal Drug Administration (FDA) as an antidepressant in 2011. The drug is a serotonin 5-HT reuptake inhibitor and a partial agonist of the serotonin 5-HT1A receptor like the anti-anxiety drug buspirone (Buspar). Neither buspirone nor vilazodone is associated with significant sexual dysfunction, unlike most of the antidepressants that only inhibit the serotonin transporter (selective serotonin reuptake inhibitors or SSRIs). Researcher Leslie Citrome et al. reported at the 2014 meeting of the American Psychiatric Association that at 40mg/day, the rate of remission was 32% on vilazodone versus 20% on placebo.
At the same meeting, researcher Carl Gommoll et al. reported on vilazodone’s side effects. The drug was generally well-tolerated. Side effects that occurred in 5% or more of the patients taking vilazodone and half as many taking placebo included diarrhea, nausea, vomiting, and insomnia.
New Antidepressant Vortioxetine May Improve Cognition and Treatment-Resistant Depression
Vortioxetine (Brintellix) is a new antidepressant that has a range of effects on serotonin receptors, making it different from selective serotonin reuptake inhibitors (SSRIs), the most common type of antidepressants, which work only on the serotonin transporter. Researcher Johan Areberg et al. reported at the 2014 meeting of the American Psychiatric Association that the drug is an antagonist at receptors 5-HT3, 5-HT7, and 5-HT1D; a partial agonist at 5-HT1B; a full agonist at 5-HT1A; and an inhibitor of the 5-HT transporter. The researchers suggested that at doses of 5mg/day, vortioxetine occupies the 5-HT3 receptors and 50% of the serotonin transporter. As dosage increases to 20mg/day, vortioxetine is believed to occupy all of the serotonin targets at clinically relevant levels. Doses of 20mg/day were found to be effective in nine studies. Researcher Gennady Smagin et al. also reported that vortioxetine activates central histamine receptors.
Vortioxetine appears to be useful in patients who have previously failed to respond to antidepressants. Researcher George I. Papakostas et al. reported that in a cohort of about 500 patients who responded inadequately to previous prescriptions of selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs), the 252 taking vortioxetine improved more than the 241 taking the antidepressant agomelatine.
Editor’s Note: Vortioxetine’s superior effects are impressive, as agomelatine, which is approved for use in at least 41 countries including the UK, Canada, and Australia, but is not available in the US, has previously been shown to be more effective than a number of SSRIs in head-to-head comparisons. Agomelatine improves sleep and circadian rhythms via its dual effects as an agonist at melatonin M1 and M2 receptors and an inhibitor of 5HT2C receptors, which results in the release of norepinephrine and dopamine in the frontal cortex.
Vortioxetine may be unique among antidepressants in that it appears to improve cognition. Researcher John E. Harrison et al. reported that patients saw increases in executive function, attention, speed of processing, and memory while taking vortioxetine. This is consistent with studies in aged mice, whose cognition improves more on vortioxetine than on the SSRI fluoxetine, according to researcher Yan Li and colleagues.
