Quetiapine Extended Release (Seroquel XR)
Once-daily extended-release quetiapine tablet with a peak around 6 hours. It provides comparable overall exposure to the same total daily dose of immediate-release quetiapine given twice daily.
Projected serum levels — 300 mg, once daily
Maintenance schedule: 300 mg once daily (oral).
Loading schedule: 361 mg on day 1, then 300 mg once daily — reaching therapeutic levels sooner.
Modeled steady state after ~1 days: peak ≈ 164 mg, trough ≈ 50.2 mg body load. Population-based estimate over 15 days for a 300 mg dose at a 70 kg reference body mass — the interactive app scales curves to your doses, timing, and body mass.
Key facts
- Category
- Antipsychotic
- Route modeled
- Oral
- Model confidence
- predicted
- Half-life
- 7 h
- Common dose
- 300 mg
- Suggested maximum
- 800 mg/day
- Reference dose range
- 50–800 mg (single dose)
- Suggested cadence
- once daily
Research behind this entry
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Quetiapine monotherapy for bipolar II depression: a double-blind, placebo-controlled study (EMBOLDEN II)
Large RCT (740 patients) demonstrating quetiapine 300-600 mg/day monotherapy significantly improved bipolar depression versus placebo, with response rates of 57-58% versus 46%.
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A randomized, placebo-controlled trial of quetiapine augmentation for treatment-resistant major depressive disorder
Pivotal trial establishing quetiapine XR 150-300 mg/day as effective augmentation for treatment-resistant MDD, significantly reducing MADRS scores versus antidepressant monotherapy.
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Clinical pharmacokinetics of quetiapine and its active metabolite norquetiapine
Comprehensive PK review establishing quetiapine half-life of 6-7 hours, active metabolite norquetiapine with half-life of 12 hours, CYP3A4-dependent metabolism, and dose-proportional pharmacokinetics.
3 published studies referenced in the app, each with a plain-language summary.