Brexpiprazole for Agitation Associated With Dementia Due to Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by progressive cognitive and functional decline. Nearly all patients with AD develop neuropsychiatric symptoms (NPSs). Agitation is one of the most distressing and challenging NPS. Brexpiprazole is an oral antipsychotic and is the first approved pharmacologic agent in the United States for the treatment of agitation associated with dementia due to AD. Its effect is thought to be from its partial serotonin 5-HT_1A and dopamine D₂ receptor agonist activity and serotonin 5-HT_2A receptor antagonism. Brexpiprazole is a maintenance medication, and it should not be used "as needed" or as a "PRN" treatment for breakthrough agitation. Brexpiprazole is a major substrate of CYP2D6 and CYP3A4. Dose adjustments may be required for drug interactions or impaired renal or hepatic function. Clinical trials found brexpiprazole 2 to 3 mg/d demonstrated significant improvements in agitation, with brexpiprazole showing an approximate 5-point greater reduction on change in the Cohen-Mansfield Agitation Inventory total score at week 12 from baseline compared with placebo. Brexpiprazole is generally well tolerated and safe, and common adverse reactions when used for this indication include dizziness, headaches, insomnia, nasopharyngitis, somnolence, and urinary tract infections. Like other antipsychotics used for agitation in AD, brexpiprazole is associated with higher mortality rates compared with placebo. In a long-term care setting, there are several considerations for its use. Benefits include an oral agent that is well tolerated and clinical data showing statistically significant effects on agitation. However, brexpiprazole has not been studied in head-to-head clinical trials against other antipsychotics, and there are differing opinions if the agitation score reductions translate to a clinically meaningful difference. The approval of brexpiprazole signals favorably for upcoming agents for this indication, including escitalopram and dextromethorphan-bupropion. Both escitalopram and dextromethorphan-bupropion are currently undergoing clinical trials.