Pharmacology · Second-generation antipsychotics
Quetiapine !
A sedating atypical antipsychotic for schizophrenia and for both manic and depressive phases of bipolar disorder; few movement effects.
Updated 2026-11-01
The figure shows risperidone in the human D2 receptor; quetiapine binds the same site loosely (no quetiapine-bound D2 structure exists).
Mechanism of action
Quetiapine blocks D2 receptors weakly and briefly and 5-HT2A receptors more strongly, with strong H1 and α1 blockade. Weak D2 binding means few extrapyramidal effects and little prolactin rise; H1 and α1 blockade give sedation and orthostatic hypotension.
- Quetiapine weakly blocks D2 and blocks 5-HT2A
- Psychotic, manic and bipolar depressive symptoms improve
- Strong H1 and α1 block: sedation and dizziness on standing
Pharmacokinetics
- Absorption
- Taken by mouth (immediate- and extended-release tablets)
- Metabolism
- Liver, mainly CYP3A4: strong inhibitors raise its levels and inducers (phenytoin, carbamazepine, rifampicin) lower them markedly
Indications
- Schizophrenia
- Manic episodes of bipolar I disorder
- Depressive episodes of bipolar disorder
- Maintenance in bipolar I disorder, with lithium or valproate
Adverse effects
Common
- Sedation
- Dizziness and orthostatic hypotension
- Dry mouth and constipation
- Weight gain
Contraindications
- Hypersensitivity to quetiapine
Key interactions
- Ketoconazole and other strong CYP3A4 inhibitors
- Much higher quetiapine levels
- Phenytoin, carbamazepine and other strong CYP3A4 inducers
- Much lower levels and loss of effect
- Other QT-prolonging drugs
- Additive QT prolongation
What is monitored
- Weight, glucose and lipids
- Mood and suicidal thoughts, especially in young people
- Blood pressure lying and standing
- Eye (lens) examination with long-term use
- Thyroid function
Administration and safety
- Immediate- and extended-release tablets are different products and are not substituted for each other
- Look-alike names: quetiapine and olanzapine are both antipsychotics with similar names
Nursing care
- Checks lying and standing blood pressure and helps the patient stand up slowly (orthostatic hypotension, falls)
- Watches for worsening mood or suicidal thoughts and teaches the family to report them
- Records weight, waist, glucose and lipids at baseline and during treatment
- Teaches the patient to avoid overheating and dehydration, and to avoid alcohol and other sedatives
Pregnancy and breastfeeding
Newborns exposed in the third trimester may have extrapyramidal or withdrawal symptoms (agitation, abnormal tone, tremor, feeding problems); use weighs benefit and risk.
Test yourself
Think of the answer, then tap the question to see it.
Why does quetiapine cause few extrapyramidal effects?
It binds D2 receptors weakly and briefly, so striatal D2 occupancy stays low.
Why does quetiapine carry a suicidality warning like antidepressants?
It is approved for bipolar depression, and antidepressant treatment raised suicidal thoughts in children, adolescents and young adults.
Which enzyme interactions change quetiapine levels the most?
CYP3A4: strong inhibitors (ketoconazole) raise them; strong inducers (phenytoin, carbamazepine) lower them.
Related drugs
← Back to the class: Second-generation antipsychotics
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - QUETIAPINE FUMARATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Quetiapine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 19 (McGraw Hill, 2023).
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Representative model, for educational purposes only.