The U.S. Food and Drug Administration's panel of independent advisers on Friday voted against the efficacy of Otsuka Pharma's drug when used in combination with Viatris' Zoloft for the treatment of adults with PTSD.

The panel voted 10-1 to say the available data does not establish the efficacy of the drug, brexpiprazole, in combination with Zoloft for treating the condition.

PTSD, a disorder caused by very stressful events, affects about 4% of U.S. adults and is commonly associated with war veterans. But natural disasters, abuse or other trauma may also trigger the condition in civilians.

The recommendation comes after the FDA's staff reviewers on Wednesday raised efficacy concerns over the use of the combination therapy, citing inconsistent trial results and a modest treatment effect.