Seroquel (quetiapine) is an atypical antipsychotic medication indicated for the treatment of schizophrenia, bipolar disorder, and as adjunctive therapy in major depressive disorder. It functions primarily as an antagonist at multiple neurotransmitter receptors, including serotonin and dopamine receptors, which underpins its broad efficacy in managing both positive and negative symptoms of psychiatric conditions. Its well-characterized pharmacokinetic profile and established dosing regimens make it a cornerstone in psychopharmacology for both acute management and maintenance therapy.

Features

• Active ingredient: Quetiapine fumarate
• Available in immediate-release (Seroquel) and extended-release (Seroquel XR) formulations
• Tablet strengths: 25 mg, 50 mg, 100 mg, 150 mg, 200 mg, 300 mg, 400 mg (immediate-release); 50 mg, 150 mg, 200 mg, 300 mg, 400 mg (extended-release)
• Receptor affinity: Antagonist activity at serotonin (5-HT2A), dopamine (D2), histamine (H1), and adrenergic (α1 and α2) receptors
• Half-life: Approximately 6 hours (immediate-release); 7 hours (extended-release)
• Metabolism: Primarily hepatic via CYP3A4

Benefits

• Effective reduction of positive symptoms in schizophrenia, including hallucinations and delusions
• Alleviation of negative symptoms such as social withdrawal and affective flattening
• Rapid stabilization of acute manic and mixed episodes in bipolar I disorder
• Adjunctive efficacy in major depressive disorder when combined with antidepressants
• Flexible dosing options accommodate individual patient tolerance and therapeutic needs
• Extended-release formulation supports once-daily dosing, enhancing adherence

Common use

Seroquel is primarily prescribed for the treatment of schizophrenia in adults and adolescents aged 13 years and older. It is also approved for acute manic and depressive episodes associated with bipolar disorder, as well as maintenance treatment to prevent recurrence. Additionally, it is used as an adjunct to antidepressants in adults with major depressive disorder who exhibit inadequate response. Off-label uses may include anxiety disorders, insomnia, and agitation in dementia, though these are not FDA-approved indications and require careful risk-benefit assessment.

Dosage and direction

Dosage must be individualized based on diagnosis, clinical response, and tolerability. For schizophrenia in adults, initial dosing is 25 mg twice daily, titrated to a target range of 300–400 mg daily by day 4. Maintenance dose typically ranges from 300–800 mg/day. For bipolar mania, initial dose is 50 mg twice daily, titrated to 400–800 mg/day by day 4. As adjunct in major depressive disorder, begin with 50 mg/day and increase to 150 mg/day. Extended-release formulations are administered once daily, preferably in the evening. Dosage adjustments are necessary in hepatic impairment, elderly patients, and when co-administered with CYP3A4 inhibitors or inducers.

Precautions

Patients should be monitored for emergence of suicidal ideation, particularly in children, adolescents, and young adults. Regular assessment of weight, blood glucose, and lipid profiles is recommended due to risks of metabolic adverse effects. Orthostatic hypotension may occur, especially during initial dose titration. Caution is advised in patients with cardiovascular disease, cerebrovascular disease, or conditions predisposing to hypotension. Seroquel may impair judgment, thinking, or motor skills; patients should avoid driving or operating machinery until response is established. Discontinuation should be gradual to avoid withdrawal symptoms.

Contraindications

Seroquel is contraindicated in patients with known hypersensitivity to quetiapine or any component of the formulation. Concomitant use with strong CYP3A4 inhibitors such as ketoconazole, itraconazole, indinavir, ritonavir, and clarithromycin is contraindicated due to significant increases in quetiapine exposure. Use is also contraindicated in conditions where CNS depression poses substantial risk, such as comatose states or significant respiratory depression.

Possible side effect

Common adverse reactions (≥5%) include somnolence, dry mouth, dizziness, constipation, asthenia, abdominal pain, postural hypotension, and weight gain. Serious side effects may include neuroleptic malignant syndrome, tardive dyskinesia, hyperglycemia and diabetes mellitus, dyslipidemia, orthostatic hypotension and syncope, leukopenia/neutropenia/agranulocytosis, cataracts, seizures, and cognitive/motor impairment. Elderly patients with dementia-related psychosis treated with antipsychotics are at increased risk of death and cerebrovascular accidents.

Drug interaction

Seroquel is primarily metabolized by CYP3A4. Concomitant use with potent CYP3A4 inhibitors (e.g., ketoconazole) increases quetiapine exposure and is contraindicated. CYP3A4 inducers (e.g., phenytoin, carbamazepine) decrease quetiapine exposure and may necessitate dose adjustment. Additive CNS depression may occur with alcohol, benzodiazepines, and other sedating agents. Seroquel may antagonize levodopa and dopamine agonists. Caution is advised with antihypertensive agents due to potential additive hypotensive effects. Interactions with drugs that prolong QTc interval warrant careful monitoring.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is close to the time of the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Doubling of doses is not recommended. For extended-release formulations, the tablet should be taken whole and not crushed, divided, or chewed.

Overdose

Symptoms of overdose may include sedation, hypotension, tachycardia, and QTc prolongation. In severe cases, coma, respiratory depression, and seizures may occur. Management is supportive and symptomatic, including gastric lavage if presented early, administration of activated charcoal, and continuous cardiac monitoring. There is no specific antidote. Hemodialysis is unlikely to be beneficial due to high protein binding.

Storage

Store at room temperature (20–25°C or 68–77°F), with excursions permitted between 15–30°C (59–86°F). Keep in a tightly closed container, protected from light and moisture. Keep out of reach of children and pets. Do not use beyond the expiration date printed on the packaging.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and individualized treatment recommendations. Do not initiate, adjust, or discontinue medication without professional supervision. Full prescribing information should be reviewed prior to administration.

Reviews

Clinical trials and post-marketing surveillance demonstrate Seroquel’s efficacy in reducing psychiatric symptoms, with particular strength in managing agitation and mood stabilization. Many clinicians report reliable sedation and anxiolysis at lower doses, though metabolic side effects remain a significant consideration in long-term therapy. Patient adherence is generally favorable with the extended-release formulation. Ongoing monitoring and individualized treatment planning are emphasized in real-world use.