Levomilnacipran (brand name Fetzima) is an antidepressant approved for the treatment of major depressive disorder in the United States. It was developed by Forest Laboratories and Pierre Fabre Group, and was approved by the Food and Drug Administration in July 2013. Levomilnacipran is the levo- enantiomer of milnacipran, and has similar effects and pharmacology, acting as a serotonin-norepinephrine reuptake inhibitor (SNRI).
The FDA approved levomilnacipran in July 2013 based on the results of one 10-week phase II and four 8-week phase III clinical trials. Four of the five trials demonstrated a statistically significant superiority to placebo as measured by the Montgomeryâ€"Ã…sberg Depression Rating Scale. Superiority to placebo was also demonstrated by improvement in the Sheehan Disability Scale. Side effects seen more often than with placebo included nausea, dizziness, sweating, constipation, insomnia, increased heart rate and blood pressure, urinary hesitancy, erectile dysfunction and delayed ejaculation in males, vomiting, tachycardia, and palpitations.
Relative to other SNRIs, levomilnacipran, as well as milnacipran, differ in that they are much more balanced reuptake inhibitors of serotonin and norepinephrine. To demonstrate, the serotonin:norepinephrine ratios of SNRIs are as follows: venlafaxine = 30:1, duloxetine = 10:1, desvenlafaxine = 10:1, milnacipran = 1:1, and levomilnacipran = 1:2. The clinical implications of more balanced elevations of serotonin and norepinephrine are unclear, but may include improved effectiveness, though also increased side effects.
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