When switching from Rexulti (brexpiprazole) to Seroquel (quetiapine), is a washout period required?

Switching from Rexulti to Seroquel: No Washout Period Required

A washout period is not required when switching from Rexulti (brexpiprazole) to Seroquel (quetiapine); instead, use gradual cross-titration over 1-4 weeks, starting quetiapine while simultaneously tapering brexpiprazole. 1

Recommended Switching Protocol

The optimal approach is gradual cross-titration informed by the half-life and receptor profiles of both medications 1:

Week 1: Initiate Cross-Titration

• Start quetiapine at 50 mg on day 1, then 100 mg on day 2,200 mg on day 3,300 mg on day 4, and 400 mg on day 5 2
• Simultaneously reduce brexpiprazole by 50% of the current dose 1
• Monitor closely for withdrawal symptoms and emerging side effects from quetiapine 1

Week 2-3: Continue Titration

• Increase quetiapine to target therapeutic dose of 400-750 mg/day based on tolerability and symptom response 3, 2
• Further reduce brexpiprazole to 25% of the original dose 1
• Watch for extrapyramidal symptoms (EPS), orthostatic hypotension, sedation, and somnolence 1, 4

Week 4: Complete the Switch

• Titrate quetiapine to final therapeutic dose within 150-750 mg/day range 2
• Discontinue brexpiprazole completely 1
• Continue monitoring for psychotic symptom severity and tolerability 1

Why No Washout Period Is Needed

Pharmacokinetic Rationale

• Brexpiprazole has a 91-hour half-life, meaning it will naturally clear gradually from the system over several weeks 5
• Quetiapine can be started immediately without waiting for brexpiprazole clearance, as abrupt switches to quetiapine do not produce significant clinical consequences 2
• The long half-life of brexpiprazole provides natural protection against abrupt discontinuation symptoms during the cross-titration 5

Receptor Profile Considerations

• Brexpiprazole is a D2 partial agonist with activity at 5-HT1A, D2, and D3 receptors 5
• Quetiapine is a D2 antagonist with low D2 antagonist properties, making it particularly suitable when switching from other antipsychotics 3
• The different pharmacodynamic profiles support switching to an agent with a different receptor profile after treatment failure 1

Critical Monitoring Parameters

During the 4-Week Switch Period

• Psychotic symptom severity using standardized scales (PANSS or BPRS) weekly 1
• Extrapyramidal symptoms using validated rating scales 1
• Orthostatic vital signs to detect hypotension, especially during quetiapine titration 1, 4
• Sedation and somnolence, which are common with quetiapine (17.8% and 15.1% incidence respectively) 4
• Metabolic parameters including weight, as quetiapine carries metabolic risk 6

Assess Treatment Response

• Evaluate efficacy at 4 weeks after completing the switch to therapeutic quetiapine doses 1, 6
• If symptoms persist or worsen by week 6, reassess diagnosis, confirm adherence, and consider alternative strategies 1

Common Pitfalls to Avoid

• Switching too abruptly: Although quetiapine tolerates abrupt switches, gradual cross-titration minimizes risk of psychotic relapse or withdrawal symptoms 2
• Inadequate quetiapine titration: Rapid titration increases risk of orthostatic hypotension and sedation 1, 4
• Failing to account for pharmacodynamic differences: Brexpiprazole's D2 partial agonism versus quetiapine's D2 antagonism can cause transient symptom changes 1
• Not confirming treatment failure before switching: Ensure brexpiprazole was given at adequate doses (2-4 mg/day) for sufficient duration (minimum 4 weeks) with verified adherence 1, 6
• Ignoring the 10-12 day steady-state period: Brexpiprazole reaches steady-state in 10-12 days, so recent dose changes may not reflect true efficacy 5