Can brexpiprazole (Rexulti) be used to treat irritability, and what is the recommended dosing and monitoring?

Rexulti (Brexpiprazole) for Irritability

Brexpiprazole is NOT approved for the treatment of irritability as a standalone indication, and effectiveness was not demonstrated in pediatric patients with irritability associated with autism spectrum disorder. 1

FDA-Approved Indications vs. Irritability

Brexpiprazole is FDA-approved only for:

• Schizophrenia (adults and adolescents ≥13 years) 1
• Adjunctive treatment of major depressive disorder (adults only) 1
• Agitation in Alzheimer's disease dementia (adults) 2, 3

The FDA label explicitly states that safety and effectiveness for irritability associated with autism spectrum disorder have NOT been established in pediatric patients. 1

Failed Clinical Trial for Irritability in Autism

In an 8-week, double-blind, placebo-controlled study of 119 pediatric patients (ages 5-17) with irritability associated with autism spectrum disorder, brexpiprazole failed to demonstrate effectiveness. 1 This study revealed concerning safety signals:

• Higher somnolence/sedation rates: 16% in brexpiprazole-treated patients vs. 5% for placebo 1
• Significant weight gain: Mean increase in age-and-gender adjusted body weight z-score of 0.3 (vs. 0.1 for placebo) 1
• 19% of patients had clinically significant weight gain (≥0.5 SD increase in z-score) vs. 5% for placebo 1
• In the open-label extension (26 weeks), mean weight increase was 4.5 kg, with 26% showing clinically significant weight gain 1

Potential Off-Label Use for Irritability in Major Depression

The only context where brexpiprazole has shown benefit for irritability is as adjunctive treatment in adults with major depressive disorder who have prominent irritability symptoms. 4

In an exploratory open-label study of 54 adults with MDD and inadequate antidepressant response:

• Target dose: 3 mg/day 4
• Clinically relevant improvements in irritability scales at 6 weeks 4
• Irritability symptoms worsened after brexpiprazole discontinuation 4
• This represents adjunctive treatment to ongoing antidepressants, not monotherapy 4

Dosing Recommendations (When Used for Approved Indications)

For schizophrenia (adolescents ≥13 years and adults):

• Target dose: 2-4 mg/day 5, 6
• Must be titrated up over 1-2 weeks 5
• Once-daily dosing 5

For adjunctive treatment in MDD (adults only):

• Target dose: 2-3 mg/day 7, 5, 6
• Optimal dose appears to be 1-2 mg/day based on dose-effect meta-analysis balancing efficacy and tolerability 7

Critical Monitoring Parameters

When brexpiprazole is used (for approved indications), monitor for:

• Weight gain: This is a significant concern, particularly in pediatric populations 1, 8

  • Monitor weight at baseline and regularly throughout treatment
  • Compare against expected growth curves in adolescents 1
  • 19.8% of adolescents experienced clinically meaningful weight gain after adjusting for natural growth 8

• Akathisia: Common adverse effect 5, 6

• Somnolence/sedation: Particularly problematic in pediatric patients 1

• Metabolic parameters: Given weight gain risk 8

Clinical Context and Cautions

Before attributing irritability to a biological disorder requiring medication, carefully assess for psychosocial stressors. 9 The American Academy of Child and Adolescent Psychiatry emphasizes that prescribers must distinguish between:

• Irritability as part of an underlying mood disorder (may respond to medication) 9
• Irritability as a behavioral reaction to psychosocial challenges (psychosocial interventions more appropriate) 9

Misattributing psychosocial reactions as biological symptoms can lead to unnecessary medication exposure and increasingly complex pharmacological strategies. 9

Bottom Line

Do not use brexpiprazole for irritability as a primary indication—it failed to demonstrate effectiveness in the only controlled trial for this purpose and carries significant risks of sedation and weight gain. 1 If irritability occurs in the context of major depressive disorder with inadequate antidepressant response in adults, brexpiprazole 1-3 mg/day as adjunctive therapy may be considered, but this is distinct from treating irritability as a standalone symptom. 4, 7