Brexpiprazole

• Schizophrenia
• Major Depressive Disorder (adjunct)
• Alzheimer's Disease Agitation
• Treatment-Resistant Depression

Brexpiprazole is an atypical antipsychotic medication approved for the treatment of schizophrenia and as adjunctive therapy for major depressive disorder (MDD). This medication is a serotonin-dopamine activity modulator that provides a unique receptor binding profile designed to minimize side effects while maintaining efficacy.

Mechanism of Action

Brexpiprazole acts as a partial agonist at dopamine D2 and serotonin 5-HT1A receptors and as an antagonist at serotonin 5-HT2A receptors. This "partial agonist" activity means brexpiprazole can stabilize dopaminergic activity—increasing it when too low and decreasing it when too high. The 5-HT1A partial agonism may contribute to antidepressant and anxiolytic effects, while 5-HT2A antagonism may reduce the risk of extrapyramidal symptoms and improve negative symptoms of schizophrenia. Compared to aripiprazole, brexpiprazole has lower intrinsic activity at D2 receptors, potentially resulting in less akathisia.

Available Formulations

Brexpiprazole is available as oral tablets in 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, and 4 mg strengths. The tablets can be taken with or without food. The medication should be stored at room temperature.

Medical Uses

Brexpiprazole is FDA-approved for the treatment of schizophrenia in adults, as adjunctive treatment to antidepressants for major depressive disorder (MDD) in adults, and for the treatment of agitation associated with dementia due to Alzheimer's disease. For MDD, it is used when antidepressants alone have not provided adequate response. Clinical trials demonstrated significant improvements in psychotic symptoms for schizophrenia and depressive symptoms when added to antidepressant therapy.

Dosing Guidelines

For schizophrenia, the recommended target dose is 2-4 mg once daily. Treatment starts at 1 mg daily on days 1-4, increases to 2 mg daily on days 5-7, then to 4 mg daily based on response. For MDD, the recommended target dose is 2 mg once daily. Treatment starts at 0.5-1 mg daily, increasing to 1 mg after one week, then to 2 mg weekly as tolerated. For agitation with Alzheimer's dementia, the target is 2-3 mg daily. Dose adjustments are required for CYP2D6 poor metabolizers and with CYP3A4 or CYP2D6 inhibitors/inducers.

Important Safety Information

Brexpiprazole carries a boxed warning regarding increased mortality in elderly patients with dementia-related psychosis (except for approved Alzheimer's agitation indication) and increased risk of suicidal thoughts and behaviors in patients under 25 with MDD. Other serious risks include cerebrovascular adverse reactions in elderly patients with dementia, neuroleptic malignant syndrome, tardive dyskinesia, metabolic changes, orthostatic hypotension, leukopenia/neutropenia, seizures, and body temperature dysregulation.

Drug Interactions

CYP3A4 inhibitors (ketoconazole, itraconazole) and CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine) increase brexpiprazole levels; dose reduction to half is recommended when used with strong inhibitors. Strong CYP3A4 inducers (rifampin) decrease brexpiprazole levels; dose doubling may be required. Avoid concomitant use with strong CYP3A4 inducers. CYP2D6 poor metabolizers require dose reduction (half the usual dose; quarter when combined with CYP3A4 inhibitors).

Special Populations

There are no adequate studies in pregnant women. Neonates exposed to antipsychotics during the third trimester may experience extrapyramidal symptoms. Brexpiprazole is excreted in rat milk; caution is advised during breastfeeding. Safety and efficacy have not been established in pediatric patients for schizophrenia or MDD. For elderly patients, the Alzheimer's agitation indication has been studied; no dose adjustment needed for age alone. No dose adjustment is needed for renal or hepatic impairment, though use is not recommended in severe hepatic impairment.