Brexpiprazole (RexultidOtsuka) is an atypical antipsychotic agent with properties and uses that are most similar to those of aripiprazole (e.g., Abilify). It is indicated for the treatment of patients with schizophrenia, and for adjunctive treatment in patients with major depressive disorder (MDD). The mechanism of action of brexpiprazole has not been fully clarified. However, it is thought to involve a combination of partial agonist activity at serotonin 5-HT1A and dopamine D2 receptors and antagonist activity at serotonin 5-HT2A receptors. The effectiveness of brexpiprazole in the treatment of patients with schizophrenia was demonstrated in two 6-week placebo-controlled studies where the new drug was demonstrated to be superior to placebo in reducing the occurrence of symptoms of schizophrenia. It was also evaluated in two 6-week placebo-controlled studies as an add-on treatment in patients with MDD for whom an antidepressant alone did not adequately treat their symptoms. Patients treated with brexpiprazole plus an antidepressant reported fewer symptoms of depression than those receiving placebo plus an antidepressant. Brexpiprazole has not been directly compared with aripiprazole or other antipsychotic agents in clinical studies. In addition to schizophrenia or MDD, aripiprazole has labeled indications for the acute treatment of patients with manic and mixed episodes associated with bipolar I disorder, the treatment of Tourette disorder, and treatment of irritability associated with autistic disorder. However, these are not labeled indications for brexpiprazole at the present time.