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 by antagonizing dopamine and serotonin receptors, which contributes to its efficacy in managing a range of psychiatric symptoms. Its distinct receptor binding profile offers a favorable balance between therapeutic effect and tolerability for many patients. This medication is available in immediate-release and extended-release formulations, allowing for tailored treatment regimens under strict medical supervision.

Features

• Active pharmaceutical ingredient: Quetiapine fumarate
• Available in immediate-release (Seroquel) and extended-release (Seroquel XR) tablet formulations
• Multiple dosage strengths ranging from 25 mg to 400 mg
• Oral administration
• Prescription-only medication
• Manufactured under stringent quality control standards

Benefits

• Effectively reduces positive and negative symptoms of schizophrenia, such as hallucinations and social withdrawal.
• Provides acute and maintenance treatment for manic and depressive episodes associated with bipolar I disorder.
• Demonstrates efficacy as an adjunctive treatment to antidepressants for Major Depressive Disorder (MDD).
• Offers a flexible dosing regimen with both immediate and extended-release options to suit individual patient needs and lifestyles.
• Exhibits a lower incidence of extrapyramidal symptoms compared to typical antipsychotics.
• Can contribute to improved overall functioning and quality of life when used as part of a comprehensive treatment plan.

Common use

Seroquel is primarily prescribed for the management of psychiatric conditions. Its most common uses include the treatment of schizophrenia in adults and adolescents aged 13 years and older. It is also widely utilized in the treatment of bipolar disorder, specifically for acute manic episodes, acute depressive episodes, and as maintenance therapy to prevent recurrence. Furthermore, it is approved for use as an add-on treatment for Major Depressive Disorder in adults who have had an inadequate response to antidepressant therapy alone. Off-label, it is sometimes used for conditions such as generalized anxiety disorder, insomnia, and delirium, though these uses require careful clinical consideration and are not FDA-approved indications.

Dosage and direction

Dosage must be individualized based on the patient’s clinical condition, response to therapy, and tolerability. For schizophrenia in adults, the initial dose is typically 25 mg twice daily, with increases in increments of 25-50 mg two or three times daily on the second and third days, as tolerated. The effective dosage range is usually 300-400 mg daily, administered in two or three divided doses. For the extended-release formulation (Seroquel XR), dosing is once daily, preferably in the evening, starting at 300 mg and adjusted within the range of 400-800 mg/day based on response and tolerability.

For bipolar mania, the initial dose is 50 mg twice daily on day one, increased to 100 mg twice daily on day two, 150 mg twice daily on day three, and 200 mg twice daily on day four. The usual effective dose is 400-800 mg/day. For bipolar depression, the recommended dose is 300 mg/day of Seroquel XR, administered once daily in the evening. As adjunctive therapy for MDD, the recommended dose is 150-300 mg/day of Seroquel XR.

Dosage adjustments are necessary in elderly patients, those with hepatic impairment, and during concomitant use of potent CYP3A4 inhibitors. The tablets should be swallowed whole with water and can be taken with or without food.

Precautions

Patients should be monitored for the emergence of suicidal thoughts and behaviors, particularly at the initiation of therapy or during dosage adjustments. Seroquel may induce orthostatic hypotension, especially during initial dose titration; caution is advised in patients with known cardiovascular disease or conditions predisposing to hypotension. There is an increased risk of mortality in elderly patients with dementia-related psychosis treated with antipsychotic drugs; Seroquel is not approved for this use. The medication can cause somnolence and impair judgment, thinking, or motor skills; patients should be cautioned about operating hazardous machinery, including automobiles, until they are reasonably certain that Seroquel does not affect them adversely. Regular monitoring for the development of tardive dyskinesia is recommended. Hyperglycemia and diabetes mellitus have been reported; monitoring of blood glucose is advisable, particularly in patients with diabetes or risk factors for diabetes. Weight gain has been observed; regular monitoring of weight is recommended. Patients should avoid becoming dehydrated or overheated, which may increase the risk of heat stroke. Discontinuation should be gradual to avoid withdrawal symptoms and potential rebound psychosis.

Contraindications

Seroquel is contraindicated in patients with a known hypersensitivity to quetiapine or any component of the formulation. Concomitant use with drugs that are potent inhibitors of the cytochrome P450 3A4 isoenzyme (e.g., ketoconazole, itraconazole, indinavir, nefazodone, clarithromycin) is contraindicated due to the significant increase in quetiapine exposure. Its use is also contraindicated in patients with severe hepatic impairment. Furthermore, it should not be used in combination with other drugs known to prolong the QT interval, due to the potential for additive effects and an increased risk of cardiac arrhythmias.

Possible side effect

A wide range of side effects has been associated with Seroquel therapy. Very common (≥1/10) side effects include somnolence, dry mouth, dizziness, constipation, weight gain, and dyslipidemia. Common (≥1/100 to <1/10) side effects include tachycardia, orthostatic hypotension, increased appetite, elevated ALT, extrapyramidal symptoms, fatigue, and dyspepsia. Uncommon (≥1/1,000 to <1/100) side effects include syncope, leukopenia, neutropenia, seizures, and neuroleptic malignant syndrome. Rare (≥1/10,000 to <1/1,000) side effects include agranulocytosis, priapism, and tardive dyskinesia. Other important side effects include hyperglycemia, which may in rare cases lead to diabetic ketoacidosis or hyperosmolar coma, and cataract development. QT prolongation has been observed, though the clinical significance is uncertain. Patients should be advised to report any unusual physical or mental changes to their healthcare provider promptly.

Drug interaction

Seroquel is primarily metabolized by CYP3A4. Concomitant administration with potent CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, indinavir, nefazodone, clarithromycin) is contraindicated as it significantly increases quetiapine plasma concentrations. Concomitant use with potent CYP3A4 inducers (e.g., phenytoin, carbamazepine, rifampin, St. John’s Wort) may significantly decrease quetiapine plasma concentrations and necessitate dose adjustment. Due to its potential for inducing hypotension and CNS depression, additive effects may occur with antihypertensive agents and other CNS depressants such as alcohol, benzodiazepines, and opioids. Seroquel may antagonize the effects of levodopa and dopamine agonists. Caution is advised when co-administering with other drugs known to prolong the QT interval (e.g., class Ia and III antiarrhythmics, certain antipsychotics, antibiotics such as erythromycin). Thioridazine administration should not be commenced for at least two weeks after discontinuing quetiapine. The dosage of Seroquel may need to be reduced when used concomitantly with phenytoin or other CYP3A4 inducers.

Missed dose

If a dose is missed, it should be taken as soon as possible. However, if it is almost time for the next scheduled dose, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not take a double dose to make up for a missed one. For the extended-release formulation (Seroquel XR), which is taken once daily, the same principle applies. It is crucial to maintain a consistent dosing schedule to ensure stable plasma concentrations and therapeutic effect. Patients should be instructed to contact their healthcare provider or pharmacist if they are uncertain about what to do after a missed dose.

Overdose

In cases of overdose, signs and symptoms are primarily an exaggeration of the drug’s known pharmacological effects. These can include severe drowsiness, sedation, tachycardia, hypotension, and QT prolongation. In severe cases, coma, respiratory depression, and seizures may occur. Management is symptomatic and supportive. Establishing and maintaining a patent airway and ensuring adequate oxygenation and ventilation are paramount. Continuous cardiac monitoring is essential due to the risk of arrhythmias. Hypotension should be managed with appropriate measures, such as intravenous fluids and vasopressors. Activated charcoal may be considered if ingestion was recent. There is no specific antidote for quetiapine overdose. Due to the high protein binding of quetiapine, dialysis is unlikely to be beneficial. All cases of suspected overdose should be referred for immediate medical attention.

Storage

Seroquel tablets should be stored at room temperature, between 15°C and 30°C (59°F and 86°F). The medication must be kept in its original container, tightly closed, and out of reach of children and pets. It should be protected from light and moisture. Unused or expired medication should not be flushed down the toilet or poured into a drain unless instructed to do so. Proper disposal through a medicine take-back program or by following FDA-recommended disposal steps (mixing with an unpalatable substance like dirt or used coffee grounds in a sealed plastic bag) is advised to prevent accidental ingestion or environmental contamination.

Disclaimer

This information is intended for educational and informational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The content provided is based on the manufacturer’s prescribing information but may not be exhaustive. Individual patient responses to medication can vary significantly. Only a qualified healthcare professional can determine the appropriate diagnosis and treatment for an individual’s specific medical situation.

Reviews

Clinical studies and post-marketing surveillance have established Seroquel as an effective agent within its approved indications. In randomized controlled trials for schizophrenia, it demonstrated significant improvement in PANSS scores compared to placebo. For bipolar depression, studies showed a significant reduction in MADRS scores. As an adjunct for MDD, it provided a statistically significant improvement in depressive symptoms. Patient-reported outcomes often cite improved mood stability and reduced psychotic symptoms. However, reviews consistently note the side effect burden, particularly somnolence and metabolic effects like weight gain, which can impact long-term adherence and require proactive management. The extended-release formulation is frequently noted for its improved convenience and potentially reduced peak-related side effects compared to the immediate-release version. Overall, it is considered a valuable therapeutic option when prescribed appropriately and monitored closely.