Quetiapine (Seroquel)


Clinical Information


HALF-LIFE: Quetiapine 6-7 hours; Norquetiapine (active metabolite)

METABOLISM: Liver (primarily CYP2D6 and CYP3A4)

STARTING DOSE: IR: 25mg-50mg PO BID; XR: 300mg PO QHS

TARGET DOSING RANGE: 50mg-800mg daily



Immediate Release (IR): Initial 25mg-50mg PO BID. Increase by 50mg-100mg per day every 1-4 days.

Extended Release (XR): Initial 150mg-300mg PO QHS. Increase by 150mg-300mg per day every 2-7 days. Max dose 800mg/day (some patients may require doses of up to 1200mg/day)

  Hypnotic dose: 50mg

  Antidepressant dose: 300mg

  Antipsychotic dose: 800mg

PREGNANCY: Minimal data on safety.

BREASTFEEDING: Minimal data on safety.

Side Effects

  • Dry mouth, sedation, orthostatic hypotension, fatigue, Neuroleptic Malignant Syndrome (VERY rare), weight gain, metabolic side effects (dyslipidemia, insulin resistance), abnormal movements (rare), seizures (rare)

FDA Indications

  1. Schizophrenia, 13yo and older
  2. Bipolar disorder (manic/mixed), 10yo and older
  3. Bipolar depression
  4. Adjunctive treatment in Unipolar Major Depression

Mechanism(s) of Action

  • Dopamine 2 (D2) Receptor Antagonist, 5HT2A Receptor Antagonist, 5HT1A Receptor Partial Agonist, 5HT2C Receptor Antagonist, 5HT7 Receptor Antagonist, Norepinephrine Reuptake Inhibitor, Histamine 1 (H1) Receptor Antagonist, Alpha-1 Receptor antagonism, Muscarinic 1 Receptor Antagonist. Norquetiapine is the active metabolite of quetiapine and has antagonist effects at NET (norepinephrine transporter), 5HT7, 5HT2C, and α2 receptors as well as partial agonist effects at 5HT1A receptors.

Additional Information

  • Very Low risk for extrapyramidal side effects (EPS)
  • Very low risk for prolactin elevation
  • Weak D2 antagonism makes quetiapine a preferred antipsychotic for Parkinson’s (although pimavanserin may be a better option)


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