What is Rexulti (Brexpiprazole)?
Rexulti (brexpiprazole) is an atypical antipsychotic medication that works as a partial agonist at serotonin 5-HT1A and dopamine D2 receptors, and as an antagonist at serotonin 5-HT2A receptors. 1
FDA-Approved Indications
Rexulti is FDA-approved for three specific conditions:
- Adjunctive treatment of major depressive disorder (MDD) in adults when used alongside antidepressant medications 1
- Treatment of schizophrenia in adults and children 13 years and older 1
- Treatment of agitation associated with dementia due to Alzheimer's disease 1
Important: Rexulti should NOT be used as an "as needed" treatment for Alzheimer's-related agitation—it requires continuous daily dosing. 1
Mechanism of Action
Brexpiprazole is classified as a serotonin-dopamine activity modulator with a unique receptor binding profile 2, 3. The drug exhibits:
- Partial agonist activity at 5-HT1A and dopamine D2/D3 receptors
- Antagonist activity at 5-HT2A, 5-HT2B, 5-HT7, and noradrenergic α1A, α1B, α1D, and α2C receptors
- Lower intrinsic activity at D2 receptors compared to aripiprazole, which theoretically translates to fewer activating adverse effects and extrapyramidal symptoms 1, 4
Available Formulations
Rexulti tablets are available in 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, and 4 mg strengths for oral administration 1. The medication can be taken with or without food 1.
Clinical Efficacy
For Schizophrenia
Brexpiprazole 2-4 mg/day demonstrated significant improvements in Positive and Negative Symptom Scale (PANSS) scores in acute schizophrenia, with maintenance treatment (1-4 mg/day) significantly delaying time to relapse 5, 4.
For Major Depressive Disorder
When used adjunctively with antidepressants, brexpiprazole 2-3 mg once daily showed superior efficacy compared to antidepressant monotherapy in patients with incomplete response to prior antidepressant treatment 6.
For Alzheimer's-Related Agitation
Brexpiprazole 2 mg demonstrated optimal therapeutic benefit with significant improvements in Cohen-Mansfield Agitation Inventory (CMAI) scores (mean difference: -5.88) and Clinical Global Impression-Severity (CGI-S) scores 7. The medication takes 6-12 weeks to separate from placebo, with particular benefit in patients with severe agitation/aggression 8.
Safety Profile and Key Warnings
Black Box Warning
Rexulti carries a black box warning for increased risk of death in elderly patients with dementia-related psychosis 1. It is NOT approved for dementia-related psychosis without agitation.
Suicide Risk
Increased risk of suicidal thoughts and actions in patients under 24 years of age, particularly within the first few months of treatment or with dose changes 1.
Common Adverse Effects
- Akathisia (more common in MDD trials than schizophrenia trials) 3
- Weight gain (moderate, with significant increases seen across studies) 3, 4
- Metabolic changes including increased triglycerides 3
- Higher doses (2-3 mg) associated with increased treatment-emergent adverse events (risk ratio: 1.20-1.33) 7
Dosing Adjustments Required
- CYP2D6 poor metabolizers (approximately 8% of Caucasians, 3-8% of Black/African Americans): Dosage reduction needed due to higher drug concentrations 1
- Moderate to severe hepatic impairment (Child-Pugh score ≥7): Lower maximum dose recommended 1
- Renal impairment (CrCl <60 mL/minute): Lower maximum dose recommended 1
Pharmacokinetics
- Peak plasma concentrations occur within 4 hours after administration
- 95% oral bioavailability
- Steady-state achieved within 10-12 days of dosing
- Highly protein-bound (hemodialysis unlikely to be useful in overdose) 1
Clinical Positioning
Brexpiprazole represents the first and only FDA-approved medication specifically for agitation in Alzheimer's dementia 9, establishing an important regulatory precedent. For schizophrenia and MDD, it provides a useful alternative with a potentially more favorable tolerability profile compared to aripiprazole, particularly regarding activating adverse effects 4, 6.
Post-marketing surveillance remains critical to fully understand the long-term safety profile, especially given the black box warning for use in elderly patients with dementia 9.