Switching from Sertraline (Zoloft) to Brexpiprazole (Rexulti)
You should not directly switch from sertraline to brexpiprazole as monotherapy, as brexpiprazole is not indicated as a standalone treatment for depression. Brexpiprazole (Rexulti) is FDA-approved only as adjunctive therapy to antidepressants for major depressive disorder (MDD), not as monotherapy 1.
The Correct Approach: Adjunctive Therapy
Add brexpiprazole to your existing sertraline regimen rather than switching. This is the evidence-based and FDA-approved strategy 1.
Dosing Protocol for Adding Brexpiprazole to Sertraline
When adding brexpiprazole to sertraline 1:
- Days 1-4: Start brexpiprazole 0.5-1 mg once daily
- Days 5-7: Increase to 1 mg once daily
- Day 8 onward: Increase to target dose of 2 mg once daily
- Maximum dose: 3 mg once daily if needed
Critical Drug Interaction Consideration
Sertraline is a CYP2D6 inhibitor, which increases brexpiprazole levels 2, 1. However, the FDA label specifically notes that in MDD clinical trials, dosage adjustments were NOT made for strong CYP2D6 inhibitors like sertraline, and these considerations are already factored into the general dosing recommendations 1. Therefore, you can use standard brexpiprazole dosing (2-3 mg/day) without adjustment when combining with sertraline 1.
Evidence Supporting Combination Therapy
Recent high-quality evidence demonstrates that brexpiprazole combined with sertraline is significantly more effective than sertraline alone for treatment-resistant symptoms 3. In a 2025 randomized controlled trial, the brexpiprazole + sertraline combination showed:
- Greater improvement in depression scores (CAPS-5 LS mean difference: -5.08 points, P=0.011) 3
- Efficacy in patients with both minimal and partial response to antidepressants 4
- Benefits across all stages of disease course 5
Monitoring Requirements
Begin monitoring within 1-2 weeks of adding brexpiprazole 6, 7:
- Assess for akathisia (occurs in 13.3% with brexpiprazole) 3
- Monitor weight (weight gain occurs in 12.5% with combination) 3
- Watch for somnolence (10% incidence) 3
- Evaluate for extrapyramidal symptoms, though risk is lower with brexpiprazole than typical antipsychotics 1
If You Must Discontinue Sertraline
If there is a compelling reason to stop sertraline entirely (severe adverse effects, drug interactions, patient preference), you cannot simply replace it with brexpiprazole monotherapy as this is not an FDA-approved indication 1.
Instead, you would need to:
- Taper sertraline slowly over 10-14 days to avoid discontinuation syndrome (dizziness, nausea, paresthesias, anxiety) 2, 8, 2
- Switch to a different antidepressant using cross-tapering or direct switch methods 9, 10
- Then add brexpiprazole as adjunctive therapy to the new antidepressant if needed
Common Pitfall to Avoid
Do not attempt to use brexpiprazole as monotherapy for depression. While it showed efficacy in combination with sertraline for PTSD 3, brexpiprazole monotherapy did NOT separate from placebo in that same trial 3. The medication requires an antidepressant backbone to be effective for mood disorders.