SEROQUEL XL 400/MG TAB 30/TAB

Indications

Approved Uses

Schizophrenia (adults; XR also approved in adolescents 13-17 years in many jurisdictions), Bipolar I disorder: acute manic episodes and acute depressive episodes, and maintenance (as adjunct to lithium or valproate); Major depressive disorder: adjunctive therapy in adults.

Off-Label Uses

Generalized anxiety disorder, Post-traumatic stress disorder (PTSD), Insomnia, Obsessive-compulsive disorder (adjunctive), Delirium, Borderline personality disorder

Dosage & Administration

Dosing by Condition

Adults-Schizophrenia (XR): Day 1: 300 mg once daily; Day 2: 600 mg once daily; maintenance 400-800 mg once daily. Bipolar I mania (XR): Day 1: 300 mg; Day 2: 600 mg; maintenance 400-800 mg once daily. Bipolar depression (XR): 50 mg Day 1, 100 mg Day 2, 200 mg Day 3, 300 mg Day 4 (target 300 mg once daily). MDD adjunct (XR): start 50 mg once daily; titrate to 150 mg by Day 3; usual 150-300 mg once daily.

Initial Dose

Schizophrenia: 300mg once daily; Bipolar mania: Day 1: 300mg, Day 2: 600mg, Day 3: 400-800mg once daily

Maintenance Dose

400-800mg once daily for schizophrenia and bipolar mania; 300mg once daily for bipolar depression; 150-300mg once daily for MDD adjunctive therapy

Maximum Dose

800 mg per day.

Children's Dosage

Schizophrenia (adolescents 13-17 years, immediate-release only): Initial 25mg twice daily, titrate to 400-800mg/day. Bipolar mania (children 10-17 years, immediate-release only): Initial 25mg twice daily, titrate to 400-600mg/day. XL formulation is not approved for pediatric use.

Dose Adjustment Notes

Use lower starting doses and slower titration in elderly/debilitated patients and in hepatic impairment. Avoid concomitant strong CYP3A4 inhibitors; if unavoidable, reduce quetiapine dose to about one-sixth. With strong CYP3A4 inducers, higher doses may be required; if an inducer is stopped, reduce quetiapine dose accordingly. When switching IR to XR, the same total daily dose may be used (clinical judgment).

How to Take

Swallow Seroquel XL/XR tablets whole with water; do not crush, chew, or split. Take once daily, preferably in the evening. Take without food or with a light meal; avoid taking with a high-fat meal and take consistently with respect to meals.

Side Effects

Common Side Effects

Somnolence/drowsiness, dizziness, dry mouth, constipation, orthostatic hypotension, weight gain and increased appetite, fatigue, headache; metabolic changes can occur (increased glucose and lipids).

Side Effect Frequency

Very common (≥10%): somnolence/sedation, dizziness, dry mouth, headache, weight gain. Common (1-10%): constipation, orthostatic hypotension, tachycardia, fatigue/asthenia, increased appetite, dyspepsia, nasal congestion, peripheral edema, blurred vision, abnormal dreams. Metabolic/lab changes commonly reported with quetiapine XR include increases in triglycerides/total cholesterol and increases in blood glucose (frequency varies by study/label section). Uncommon/rare (<1% or post‑marketing): QT prolongation/arrhythmias, seizures, neuroleptic malignant syndrome, tardive dyskinesia, severe neutropenia/agranulocytosis, hyponatremia (SIADH), priapism, cataract/lens changes.

Safety & Warnings

Contraindications

Hypersensitivity to quetiapine or any excipients

Warnings & Precautions

Key warnings/precautions: dementia-related psychosis mortality (not approved); suicidality risk in children/adolescents/young adults; metabolic monitoring (weight, glucose, lipids); orthostatic hypotension (slow titration); NMS; tardive dyskinesia; QT prolongation risk (avoid in high-risk patients/with QT-prolonging drugs); leukopenia/neutropenia (CBC if risk/symptoms); seizures; dysphagia/aspiration risk; cataracts (consider eye exams); potential for withdrawal with abrupt stop.

Age Restriction

Not approved for patients <18 years for Seroquel XR/XL indications; pediatric approvals (where applicable) are for immediate‑release quetiapine, not XR/XL.

Driving Warning

Avoid Driving

Drug Interactions

Drug Interactions

Major: strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) markedly increase quetiapine-avoid; strong CYP3A4 inducers (e.g., carbamazepine, phenytoin, rifampin, St John’s wort) markedly decrease levels-avoid/alternative. Other clinically important: additive CNS depression with alcohol/benzodiazepines/opioids; enhanced hypotension with antihypertensives; additive QT-risk with QT‑prolonging drugs; caution with other CYP3A4 inhibitors (moderate) and with dopamine agonists/levodopa (pharmacodynamic antagonism).

Interaction Severity

MAJOR: Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin, ritonavir) and strong CYP3A4 inducers (e.g., carbamazepine, phenytoin, rifampin) due to large exposure changes; QT-prolonging drugs are clinically significant especially in at-risk patients. MODERATE: CNS depressants (alcohol, opioids, benzodiazepines), antihypertensives (additive hypotension), other QT-prolonging agents, and dopamine agonists/levodopa (pharmacodynamic antagonism).

Food Interaction

Take without food or with a light meal; avoid administration with a high-fat meal and take consistently with respect to meals.

Alcohol Interaction

Dangerous

Special Populations

Pregnancy

Not assigned (risk summary: Neonates exposed to antipsychotics during 3rd trimester at risk of extrapyramidal symptoms

Children

Schizophrenia (adolescents 13-17 years, immediate-release only): Initial 25mg twice daily, titrate to 400-800mg/day. Bipolar mania (children 10-17 years, immediate-release only): Initial 25mg twice daily, titrate to 400-600mg/day. XL formulation is not approved for pediatric use.

Elderly

Start at 50mg/day and titrate slowly in increments of 50mg/day. Lower maintenance doses may be sufficient. Monitor closely for orthostatic hypotension, sedation, and metabolic effects. Not recommended for dementia-related psychosis.

Kidney Impairment

No dosage adjustment generally required in renal impairment.

Liver Impairment

Hepatic impairment: start low and titrate slowly; for XR/XL, start 50 mg once daily and increase by 50 mg/day as tolerated to effective dose.

Storage & Patient Advice

Missed Dose

Take as soon as remembered. If it is almost time for the next dose, skip the missed dose and continue with the regular schedule. Do not take a double dose.

Stopping the Medicine

Do not stop abruptly; taper gradually (commonly over at least 1-2 weeks, individualized) to reduce withdrawal symptoms and relapse risk.

Overdose

Typical overdose: marked sedation/somnolence, tachycardia, hypotension, anticholinergic effects; may include QT prolongation/arrhythmias and coma. Management: emergency care with airway/ventilation support, activated charcoal if appropriate, continuous cardiac/vital monitoring, IV fluids/vasopressors as needed; no specific antidote.

Patient Counseling

Swallow XR/XL tablet whole; do not crush/chew/split. Take once daily in the evening; take without food or with a light meal and avoid high-fat meals. May cause drowsiness/dizziness-avoid driving/alcohol and rise slowly. Do not stop abruptly without prescriber advice. Report abnormal movements, severe rash, fever/rigidity, fainting/palpitations, signs of high blood sugar, or significant weight gain; keep follow-ups for metabolic monitoring.

Monitoring Requirements

Baseline and periodic: weight/BMI and waist circumference (if used), blood pressure, fasting glucose or HbA1c, fasting lipid panel; assess for EPS/tardive dyskinesia, sedation/orthostasis, and suicidality (especially in younger patients). CBC if clinically indicated (history of low WBC/neutropenia or infection symptoms). Consider ECG in patients with cardiac disease, electrolyte abnormalities, or on QT-prolonging drugs. Consider eye exam if long-term use or visual symptoms (cataract signal).

Pharmacology

Mechanism of Action

Quetiapine is an atypical antipsychotic with antagonism at 5‑HT2A and D2 receptors and activity at H1 and alpha-1/alpha-2 receptors; its active metabolite norquetiapine contributes via norepinephrine transporter (NET) inhibition and 5‑HT1A partial agonism. The XR/XL formulation provides extended absorption enabling once-daily dosing.

Onset of Action

Sedation may occur within hours; antipsychotic/mood symptom improvement typically begins within 1-2 weeks, with full therapeutic response often taking 4-6 weeks.

Duration of Effect

Sedative effects may last several hours; extended-release clinical effect supports once-daily dosing with approximately 24-hour coverage.

Half-Life

Approximately 7 hours (quetiapine); active metabolite norquetiapine approximately 12 hours

Bioavailability

Absolute oral bioavailability is low (approximately ~9%) due to first-pass metabolism; XR has similar overall exposure to IR at equivalent total daily doses (relative bioavailability approximately ~100%).

Metabolism

Extensively hepatically metabolized primarily by CYP3A4 to multiple metabolites; norquetiapine (N-desalkyl quetiapine) is a major active metabolite.

Excretion

Excreted mainly as metabolites: ~73% in urine and ~20-21% in feces; <5% excreted unchanged.

Protein Binding

Approximately 83%.

Product Information

Available Dosage Forms

Quetiapine is available as immediate-release tablets and extended-release tablets (XR/XL); some markets also have an oral solution for immediate-release quetiapine (availability varies by country).

Composition per Dose

Each extended-release film-coated tablet: 400mg quetiapine (as quetiapine fumarate 461.1mg)

Generic Availability

Yes

OTC Alternatives

No OTC alternative

Psych Class

Antipsychotic-Atypical

Controlled Substance

No

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