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Indications/Uses
Used in the treatment of schizophrenia and of mania associated with bipolar disorder.
Dosage/Direction for Use
Schizophrenia: The usual initial dose is 25 mg twice daily on day one, 50 mg twice daily on day two, 100 mg twice daily on day three, and 150 mg twice daily on day four. The dosage is then adjusted according to response to a usual range of 300 to 450 mg daily given in 2 or 3 divided doses, although 150 mg daily may be adequate for some patients. The maximum recommended dose is 750 mg daily.
Mania: The initial dose is 50 mg twice daily on day one, 100 mg twice daily on day two, 150 mg twice daily on day three, and 200 mg twice daily on day four. The dose may then be adjusted to a usual range of 400 to 800 mg daily, although, in some patients, 200mg daily may be adequate. Increments in dosage should be no greater than 200 mg daily.
Other: Elderly: Quetiapine should be given in reduced doses to the elderly; a recommended starting dose is 25 mg daily increased in steps of 25 to 50 mg daily according to response. Hepatic and Renal impairment: Reduced doses are also recommended in patients with hepatic or renal impairment. The recommended starting dose is 25 mg daily increased in steps of 25 to 50 mg daily according to response.
Mania: The initial dose is 50 mg twice daily on day one, 100 mg twice daily on day two, 150 mg twice daily on day three, and 200 mg twice daily on day four. The dose may then be adjusted to a usual range of 400 to 800 mg daily, although, in some patients, 200mg daily may be adequate. Increments in dosage should be no greater than 200 mg daily.
Other: Elderly: Quetiapine should be given in reduced doses to the elderly; a recommended starting dose is 25 mg daily increased in steps of 25 to 50 mg daily according to response. Hepatic and Renal impairment: Reduced doses are also recommended in patients with hepatic or renal impairment. The recommended starting dose is 25 mg daily increased in steps of 25 to 50 mg daily according to response.
Administration
May be taken with or without food: Swallow whole, do not split/chew/crush.
Contraindications
Hypersensitivity. Co-administration w/ cytochrome P450 3A4 inhibitors eg, HIV-PIs, azole antifungals, erythromycin, clarithromycin & nefazodone.
Special Precautions
Quetiapine should be used with caution in patients with hepatic or renal impairment, with cardiovascular disease or other conditions predisposing to hypotension, or with a history of seizures.
Quetiapine may affect the performance of skilled tasks including driving.
Quetiapine may affect the performance of skilled tasks including driving.
Adverse Reactions
The most frequent adverse effects with quetiapine are somnolence, dizziness, constipation, orthostatic hypotension, dry mouth, and raised liver enzyme values. Quetiapine has been associated with a low incidence of extrapyramidal symptoms. Rises in prolactin concentrations may be less than with chlorpromazine. Weight gain particularly during early treatment has also been noted. Clinical monitoring for hyperglycemia has been recommended, especially in patients with or at risk of developing diabetes. Neuroleptic malignant syndrome is rare with quetiapine but tardive dyskinesia may occur after long-term treatment. Tachycardia and occasionally, syncope have been reported; prolongation of the QT interval is rarely significant. Leucopenia, neutropenia, and eosinophilia have also been reported with quetiapine.
Other adverse effects have included mild asthenia, anxiety, fever, hypertension, myalgia, rhinitis, dyspepsia, rises in plasma- triglyceride and cholesterol concentrations, and reduced plasma thyroid hormone concentrations. There have been rare reports of seizures, hypersensitivity reactions including angioedema, priapism, and peripheral edema. Asymptomatic changes in the lens of the eye have occurred in patients during long-term treatment with quetiapine.
Other adverse effects have included mild asthenia, anxiety, fever, hypertension, myalgia, rhinitis, dyspepsia, rises in plasma- triglyceride and cholesterol concentrations, and reduced plasma thyroid hormone concentrations. There have been rare reports of seizures, hypersensitivity reactions including angioedema, priapism, and peripheral edema. Asymptomatic changes in the lens of the eye have occurred in patients during long-term treatment with quetiapine.
Drug Interactions
The central effects of other CNS depressants, including alcohol, may be enhanced by Quetiapine. Quetiapine may antagonize the actions of dopaminergics such as levodopa.
CYP3A4 is the main isoenzyme responsible for cytochrome P450 mediated metabolism of Quetiapine and caution is advised when Quetiapine is used with potent inhibitors of CYP3A4 such as erythromycin, fluconazole, itraconazole, and ketoconazole; lower doses of quetiapine should be used when given with such inhibitors. Conversely, enzyme inducers such as carbamazepine and phenytoin may decrease the plasma concentrations of quetiapine, and higher doses of quetiapine may be necessary. Thioridazine has also been reported to increase the clearance of quetiapine.
CYP3A4 is the main isoenzyme responsible for cytochrome P450 mediated metabolism of Quetiapine and caution is advised when Quetiapine is used with potent inhibitors of CYP3A4 such as erythromycin, fluconazole, itraconazole, and ketoconazole; lower doses of quetiapine should be used when given with such inhibitors. Conversely, enzyme inducers such as carbamazepine and phenytoin may decrease the plasma concentrations of quetiapine, and higher doses of quetiapine may be necessary. Thioridazine has also been reported to increase the clearance of quetiapine.
Storage
Store at temperatures not exceeding 30°C.
Action
Pharmacology: Pharmacodynamics: Mechanism of Action: Quetiapine fumarate is a dibenzothiazepine atypical antipsychotic. It is reported to have affinity for serotonin (5-HT2), histaminergic (H1), and adrenergic (α1 and α2) receptors as well as dopamine D2 receptors.
Pharmacokinetics: Quetiapine is well absorbed following oral administration and widely distributed throughout the body. Peak plasma concentrations are reached in about 1.5 hours. It is about 83% bound to plasma proteins. Quetiapine is extensively metabolized in the liver by sulfoxidation mediated mainly by the cytochrome P450 isoenzyme CYP3A4 and by oxidation. It is excreted mainly as inactive metabolites, about 73% of a dose appearing in the urine and about 20% in the feces. The elimination half-life has been reported to be about 6 to 7 hours.
Pharmacokinetics: Quetiapine is well absorbed following oral administration and widely distributed throughout the body. Peak plasma concentrations are reached in about 1.5 hours. It is about 83% bound to plasma proteins. Quetiapine is extensively metabolized in the liver by sulfoxidation mediated mainly by the cytochrome P450 isoenzyme CYP3A4 and by oxidation. It is excreted mainly as inactive metabolites, about 73% of a dose appearing in the urine and about 20% in the feces. The elimination half-life has been reported to be about 6 to 7 hours.
MedsGo Class
Antipsychotics
Features
Dosage
25 mg
Ingredients
- Quetiapine
Packaging
Film-Coated Tablet 1's
Generic Name
Quetiapine Fumarate
Registration Number
DRP-5721
Classification
Prescription Drug (RX)
Product Questions
Questions
