Medications: Seroquel^® – quetiapine

SEROQUEL is an atypical antipsychotic indicated for the treatment of:

• Schizophrenia (1.1)
• Bipolar I disorder manic episodes (1.2)
• Bipolar disorder, depressive episodes (1.2)

DOSAGE AND ADMINISTRATION

• Geriatric Use: Consider a lower starting dose (50 mg/day), slower titration and careful monitoring during the initial dosing period in the elderly (2.3, 8.5)
• Hepatic Impairment: Lower starting dose (25 mg/day) and slower titration may be needed (2.4, 8.7, 12.3)

• Most common adverse reactions (incidence ≥5% and twice placebo): Adults: somnolence, dry mouth, dizziness, constipation, asthenia, abdominal pain, postural hypotension, pharyngitis, weight gain, lethargy, ALT increased, dyspepsia (6.1)
• Children and Adolescents: somnolence, dizziness, fatigue, increased appetite, nausea, vomiting, dry mouth, tachycardia, weight increased (6.1)

Known hypersensitivity to SEROQUEL or any components in the formulation. (4)

WARNINGS AND PRECAUTIONS:

• Cerebrovascular Adverse Reactions: Increased incidence of cerebrovascular adverse reactions (e.g., stroke, transient ischemic attack) has been seen in elderly patients with dementia-related psychoses treated with atypical antipsychotic drugs (5.3)
• Neuroleptic Malignant Syndrome (NMS): Manage with immediate discontinuation and close monitoring (5.4)
• Metabolic Changes: Atypical antipsychotics have been associated with metabolic changes. These metabolic changes include hyperglycemia, dyslipidemia, and weight gain (5.5)
• Hyperglycemia and Diabetes Mellitus: Monitor patients for symptoms of hyperglycemia including polydipsia, polyuria, polyphagia, and weakness. Monitor glucose regularly in patients with diabetes or at risk for diabetes
• Dyslipidemia: Undesirable alterations have been observed in patients treated with atypical antipsychotics. Appropriate clinical monitoring is recommended, including fasting blood lipid testing at the beginning of, and periodically, during treatment
• Weight Gain: Gain in body weight has been observed; clinical monitoring of weight is recommended
• Tardive Dyskinesia: Discontinue if clinically appropriate (5.6)
• Hypotension: Use with caution in patients with known cardiovascular or cerebrovascular disease (5.7)
• Increased Blood Pressure in Children and Adolescents: Monitor blood pressure at the beginning of, and periodically during treatment in children and adolescents (5.9)
• Leukopenia, Neutropenia and Agranulocytosis: Monitor complete blood count frequently during the first few months of treatment in patients with a pre-existing low white cell count or a history of leukopenia/neutropenia and discontinue SEROQUEL at the first sign of a decline in WBC in absence of other causative factors (5.10)
• Cataracts: Lens changes have been observed in patients during long-term quetiapine treatment. Lens examination is recommended when starting treatment and at 6-month intervals during chronic treatment (5.11)
• Anticholinergic(antimuscarinic) Effects: Use with caution with other anticholinergic drugs and in patients with urinary retention, prostatic hypertrophy, or constipation (5.20)

• Concomitant use of strong CYP3A4 inhibitors: Reduce quetiapine dose to one sixth when coadministered with strong CYP3A4 inhibitors (e.g., ketoconazole, ritonavir) (2.5, 7.1, 12.3)
• Concomitant use of strong CYP3A4 inducers: Increase quetiapine dose up to 5 fold when used in combination with a chronic treatment (more than 7-14 days) of potent CYP3A4 inducers (e.g., phenytoin, rifampin, St. John’s wort) (2.6, 7.1, 12.3)
• Discontinuation of strong CYP3A4 inducers: Reduce quetiapine dose by 5-fold within 7-14 days of discontinuation of CYP3A4 inducers (2.6, 7.1, 12.3)

In clinical trials, survival has been reported in acute overdoses of up to 30 grams of quetiapine. Most patients who overdosed experienced no adverse reactions or recovered fully from the reported reactions. Death has been reported in a clinical trial following an overdose of 13.6 grams of quetiapine alone. In general, reported signs and symptoms were those resulting from an exaggeration of the drug’s known pharmacological effects, i.e., drowsiness, sedation, tachycardia, hypotension, and anticholinergic toxicity including coma and delirium. Patients with pre-existing severe cardiovascular disease may be at an increased risk of the effects of overdose [see Warnings and Precautions (5.12)]. One case, involving an estimated overdose of 9600 mg, was associated with hypokalemia and first-degree heart block. In post-marketing experience, there were cases reported of QT prolongation with overdose.

Management of Overdosage: Establish and maintain an airway and ensure adequate oxygenation and ventilation. Cardiovascular monitoring should commence immediately and should include continuous electrocardiographic monitoring to detect possible arrhythmias. Appropriate supportive measures are the mainstay of management. For the most up-to-date information on the management of Seroquel overdosage, contact a certified Regional Poison Control Center (1-800-222-1222).