quetiapine

General information

• Class: Antipsychotic
• Common US brands: SEROQUEL
• Typical dose range: Schizophrenia (IR): day 1 25 mg BID, titrate to 300–400 mg/day by day 4; maintenance 300–800 mg/day divided BID.
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2025-09-23

Dosing & forms

• Forms/strengths: Immediate-release tablets: 25, 50, 100, 200, 300, 400 mg; extended-release tablets: 50, 150, 200, 300, 400 mg.
• Frequency: Schizophrenia (IR): day 1 25 mg BID, titrate to 300–400 mg/day by day 4; maintenance 300–800 mg/day divided BID.
• Typical range: Schizophrenia (IR): day 1 25 mg BID, titrate to 300–400 mg/day by day 4; maintenance 300–800 mg/day divided BID.

Mechanism (brief)

Antagonist at 5‑HT2A and D2 (transient), strong H1 and alpha‑1 activity.

Metabolism & Half‑life

• Metabolism: CYP3A4
• Half‑life: Steady-state mean 6 h

Therapeutic Drug Monitoring (TDM)

Recommended: No

Sources

• SEROQUEL label — DailyMed
• The American Psychiatric Association Practice Guideline for the Treatment of Patients With Schizophrenia — American Psychiatric Association (2020)
• AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology — Pharmacopsychiatry (2018)
• The CANMAT and ISBD Guidelines for the Management of Patients With Bipolar Disorder: 2021 Update — Bipolar Disorders (2021)
• Comparative efficacy and acceptability of antimanic drugs in acute mania: a multiple-treatments meta-analysis — The Lancet (2011)