New antipsychotic drugs for the treatment of agitation and psychosis in Alzheimer's disease: Focus on brexpiprazole and pimavanserin

Behavioral and psychological symptoms of dementia are symptoms of disturbed perception, mood, behavior, and thought content that occurred frequently. These symptoms, which include apathy, depression, anxiety, psychosis, agitation, and aggression, can serve as predictors of and early clinical diagnostic markers for Alzheimer's disease (AD) and are common precipitants of institutional care. Agitation and psychosis are associated with accelerated disease progression and increased tau phosphorylation in patients with AD. Current guidelines recommend the use of second-generation antipsychotics for the treatment of agitation and psychosis in AD, but only after first-line non-pharmacological interventions and for no longer than 12 weeks because long-term use of these drugs is associated with an increased risk of mortality and an increased frequency of cerebrovascular events. Therefore, new antipsychotic drugs with improved efficacy and safety are needed as an alternative to current antipsychotic drugs. In this report, we discuss some of the most relevant advances in the field of agitation and psychosis in AD and focus on the recent positive clinical evidence observed with two new antipsychotics drugs: brexpiprazole and pimavanserin. Brexpiprazole is a receptor partial agonist (D2, D3, 5-HT1A), receptor antagonist (5-HT2A/B, α1B/α2C) according to the neuroscience-based nomenclature. Two recent phase III clinical trials have shown that brexpiprazole 2 mg/day is effective for the treatment of agitation in patients with AD and has an improved tolerability and safety profile compared with currently available second-generation antipsychotics. Pimavanserin is a receptor antagonist (5-HT2A, 5-HT2C) that has been given market authorization for psychosis occurring in Parkinson's disease. Recent phase II studies suggest that this drug is effective in AD patients with more severe psychosis, although further long-term studies are needed to better define the efficacy and long-term safety profile of pimavanserin for the treatment of psychosis in AD.