In a randomized, double-blind, placebo-controlled phase 3 trial, Zuranolone (an experimental oral positive allosteric modulator of the γ-aminobutyric acid type A [GABA-A] receptor) demonstrated rapid and remarkable improvements in depressive symptoms in adults suffering from major depression. The aim of this study was to determine the effectiveness and safety of a 14-day treatment regimen of 50 mg of Zuranolone.

Individuals between the ages of 18 and 64 who had severe major depressive disorder were included. Participants were assigned to self-administer Zuranolone 50 mg or placebo once every day for fourteen days. Alteration in total score on the 17-item Hamilton Depression Rating Scale (HAM-D) from baseline to day 15 was the key outcome measure. Tolerability and safety were examined by monitoring the occurrence of adverse events.

Of the total 543 subjects who were randomly assigned, 534 individuals (266 in the Zuranolone group and 268 in the placebo group) were included in the complete analysis set. In comparison to placebo recipients, subjects who received Zuranolone exhibited a notable improvement in depressive symptoms by day 15 (mean change from baseline HAM-D score: -14.1 vs. -12.3). Starting as early as day 3, there were better improvements in depressive symptoms for the Zuranolone group compared to the placebo group (least mean change from baseline HAM-D score: -9.8 vs. -6.8), and these improvements were sustained throughout the treatment and follow-up periods of the study, lasting until day 42, with the difference remaining statistically significant until day 12.

In both study groups, two subjects each encountered a serious adverse event, while adverse events led to the discontinuation of treatment in nine subjects from the Zuranolone group and four subjects from the placebo group. Zuranolone at a daily dose of 50 mg resulted in a considerably higher improvement in depressive symptoms at day 15, with a rapid onset of action by day 3. It was generally well-tolerated, with no novel safety concerns identified compared to lower dosages previously investigated. These findings yield support for the potential use of Zuranolone to relieve major depressive disorder in adults.