What it's for (Indications)
- Treatment of schizophrenia, bipolar disorder (including bipolar depression and mania, as monotherapy or adjunctive therapy to lithium or divalproex), and as an adjunctive treatment for major depressive disorder.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | Quetiapine can be taken with or without food. Dosage varies by indication and patient population: * **Schizophrenia-Adults:** Initial 25 mg twice daily; recommended 150-750 mg/day; maximum 750 mg/day. * **Schizophrenia-Adolescents (13-17 years):** Initial 25 mg twice daily; recommended 400-800 mg/day; maximum 800 mg/day. * **Bipolar Mania-Adults (Monotherapy or adjunctive to lithium/divalproex):** Initial 50 mg twice daily; recommended 400-800 mg/day; maximum 800 mg/day. * **Bipolar Mania-Children and Adolescents (10-17 years), Monotherapy:** Initial 25 mg twice daily; recommended 400-600 mg/day; maximum 600 mg/day. * **Bipolar Depression-Adults:** Initial 50 mg once daily at bedtime; recommended 300 mg/day; maximum 300 mg/day. * **Geriatric Use:** Consider a lower starting dose (50 mg/day), slower titration, and careful monitoring during the initial dosing period. * **Hepatic Impairment:** A lower starting dose (25 mg/day) and slower titration may be needed. |
Safety & Warnings
Common Side Effects
- Patients may experience somnolence (increased sleep), dizziness, constipation, dry mouth, headache, increased appetite, weight gain, blurred vision, gastrointestinal upset, peripheral edema (swelling of hands and feet), pyrexia (fever), sleep disturbances, postural hypotension (drop in blood pressure on changing posture), liver enzyme abnormalities, thyroid hormone changes, hyperglycemia (raised blood sugar level), dyslipidemia, tachycardia (increased heart rate), palpitations, cataracts, and falls.
- Increases in blood pressure have been observed, particularly in children and adolescents.
Serious Warnings
- Black Box Warning: WARNING: Increased Mortality in Elderly Patients with Dementia-Related Psychosis; and Suicidal Thoughts and Behaviors. **Increased Mortality in Elderly Patients with Dementia-Related Psychosis:** Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Quetiapine is not approved for the treatment of patients with dementia-related psychosis. **Suicidal Thoughts and Behaviors in Adolescents and Young Adults:** Antidepressants, including quetiapine when used for bipolar depression, increased the risk of suicidal thoughts and behavior in children, adolescents, and young adults in short-term studies for major depressive disorder and other psychiatric disorders. Close monitoring for clinical worsening, suicidality, or unusual changes in behavior is essential, especially at treatment initiation and during dose changes.
- Caution is advised in patients with renal (kidney) or hepatic (liver) impairment, history of cardiovascular diseases, cerebrovascular diseases (including risk of stroke), hypotension, epilepsy, congestive heart failure, cardiac hypertrophy (enlargement of heart), hypokalemia (low potassium level in blood), hypomagnesemia (low magnesium level in blood), diabetes (raised blood sugar level), urinary retention, gastrointestinal obstruction, prostatic hypertrophy (enlargement of prostate gland), intestinal obstruction, and history of drug or alcohol abuse.
- Patients should be monitored for suicidal thoughts and behaviors, Neuroleptic Malignant Syndrome (NMS), Tardive Dyskinesia, and severe blood dyscrasias (leukopenia, neutropenia, agranulocytosis).
- Metabolic changes (hyperglycemia, dyslipidemia, weight gain) and increases in blood pressure (especially in children and adolescents) should be closely monitored.
- Use during pregnancy requires caution; there is no definite data available regarding risk, therefore consult a doctor.
- Patients should avoid driving and operating machinery as it may impair ability, and avoid consuming alcohol.
How it Works (Mechanism of Action)
The mechanism of action of quetiapine fumarate is unknown. However, it has been proposed that the efficacy of quetiapine fumarate in schizophrenia and its mood stabilizing properties in bipolar depression and mania are mediated through a combination of dopamine type 2 (D2) and serotonin type 2 (5HT2) antagonism. Antagonism at receptors other than dopamine and 5HT2 with similar receptor affinities may explain some of the other effects of quetiapine fumarate. Quetiapine fumarate’s antagonism of histamine H1 receptors may explain the somnolence observed with this drug. Quetiapine fumarate’s antagonism of adrenergic α1 receptors may explain the orthostatic hypotension observed with this drug.