Average Weight Gain with Rexulti (Brexpiprazole)
Rexulti causes modest weight gain, with an average increase of approximately 1.2-1.5 kg (2.6-3.3 lbs) over 6 weeks in short-term studies, and 2.0-3.2 kg (4.4-7.0 lbs) over one year in long-term treatment.
Short-Term Weight Gain (6 Weeks)
In the 6-week placebo-controlled trials for schizophrenia, the mean weight increase was 1.0-1.2 kg across the 1-4 mg/day dose range 1, 2. For major depressive disorder (MDD) as adjunctive therapy, the mean weight gain was slightly higher at 1.3-1.6 kg over 6 weeks 1.
The proportion of patients experiencing clinically significant weight gain (≥7% increase from baseline) during short-term treatment was:
- Schizophrenia: 10-11% of patients on 2-4 mg/day (compared to 4% on placebo) 1
- MDD: 2-5% of patients on 1-3 mg/day (compared to 2% on placebo) 1
Long-Term Weight Gain (Up to 1 Year)
Long-term data shows progressive but moderate weight gain over time 3, 4, 5:
- At 26 weeks: Mean increase of 2.7-2.9 kg 1, 3
- At 52 weeks: Mean increase of 2.0-3.2 kg depending on indication 1, 3, 5
In long-term studies:
- 20-30% of patients experienced ≥7% weight gain at any point during treatment 1, 3
- 4-10% of patients experienced ≥7% weight loss 1
- Discontinuation due to weight gain was rare (0.6% in schizophrenia, 4% in MDD) 1, 3
Comparative Context
Rexulti demonstrates a more favorable weight profile compared to high-risk antipsychotics like olanzapine and clozapine 6, 7. Research directly comparing newer antipsychotics found that brexpiprazole caused statistically significant but modest weight gain (2.48 lbs at 12 weeks, 5.97 lbs at 1 year), which was substantially less than olanzapine 8. The weight gain profile is similar to aripiprazole across both short-term and long-term treatment 5.
Clinical Monitoring Recommendations
Weight should be monitored at baseline and frequently thereafter, as specified in the FDA label 1. The weight gain appears dose-independent within the therapeutic range and continues gradually over the first year of treatment before plateauing 4, 2.
Important Caveats:
- Individual variation is substantial—while mean weight gain is modest, approximately 20-30% of patients will experience clinically significant weight gain
- Weight gain is generally accompanied by small, non-clinically significant changes in metabolic parameters (lipids, glucose) 4, 2
- Pediatric patients (13-17 years) showed minimal weight gain in short-term studies (0.8 kg mean increase) but require monitoring adjusted for normal growth patterns 1