Seroquel

Seroquel is the brand name for quetiapine, an atypical antipsychotic used to treat schizophrenia and bipolar disorder, including manic and depressive episodes, and as an adjunctive treatment for major depressive disorder. It is available in immediate-release and extended-release forms and is prescribed by psychiatrists and other physicians.

Quetiapine acts as an antagonist at dopamine D2 and serotonin 5-HT2A receptors, with the active metabolite norquetiapine contributing to antidepressant effects. It also blocks histamine H1 and alpha-adrenergic receptors, which contributes to sedation and orthostatic hypotension.

Quetiapine is metabolized in the liver by the enzyme CYP3A4 to norquetiapine, which can contribute to its clinical effects. The drug is available in immediate-release and extended-release formulations; dosing is typically tailored to the indication and the formulation. In general, therapeutic dosing ranges across indications are in the hundreds of milligrams per day, with immediate-release forms often taken two to three times daily and extended-release forms taken once daily.

Common adverse effects include somnolence, dizziness, dry mouth, weight gain, and orthostatic hypotension. Metabolic effects such as weight gain, glucose dysregulation, and lipid changes can occur. Extrapyramidal symptoms are less frequent than with older antipsychotics but can occur; rare cases of tardive dyskinesia have been reported. QT prolongation may occur at higher doses. Serious risks include increased mortality in elderly patients with dementia-related psychosis and suicidality in young people. Contraindications include hypersensitivity to quetiapine; caution is advised in pregnancy and lactation. Drug interactions include CYP3A4 inhibitors or inducers, alcohol, and other sedatives.