SEROQUEL XR
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SEROQUEL XR (SEROQUEL XR).
SEROQUEL XR (quetiapine fumarate) is an atypical antipsychotic that acts as an antagonist at multiple neurotransmitter receptors: serotonin 5-HT1A and 5-HT2A, dopamine D1 and D2, histamine H1, and adrenergic α1 and α2 receptors. It also has partial agonist activity at 5-HT1A receptors. The therapeutic efficacy in schizophrenia and bipolar disorder is primarily attributed to dopamine D2 and serotonin 5-HT2A antagonism.
| Metabolism | Primarily metabolized by cytochrome P450 3A4 (CYP3A4) to its major active metabolite, norquetiapine. Minor pathways include CYP2D6 and CYP2C19. Norquetiapine has similar pharmacologic activity and is further metabolized by CYP3A4. |
| Excretion | Primarily hepatic; 70-73% excreted in urine as metabolites (mostly inactive), 20-24% in feces. Less than 1% excreted unchanged in urine. |
| Half-life | Terminal elimination half-life: approximately 7 hours (range 6-9 hours) for the extended-release formulation. Clinical context: once-daily dosing achieves steady-state within 2 days. |
| Protein binding | Approximately 83% bound to serum proteins (albumin and alpha-1-acid glycoprotein). |
| Volume of Distribution | Mean apparent Vd/F is 6-7 L/kg. Clinical meaning: extensive extravascular distribution, indicating tissue binding. |
| Bioavailability | Oral (XR): 100% (extended-release formulation designed for once-daily dosing). Bioavailability is not significantly affected by food, though high-fat meals increase Cmax and AUC slightly. |
| Onset of Action | Oral (XR): Antipsychotic effect typically within 1-2 days, with significant improvement within 1 week. For mood disorders, therapeutic response may take 2-4 weeks. |
| Duration of Action | Approximately 24 hours due to extended-release formulation, allowing once-daily dosing. Clinical note: the sustained release provides stable plasma concentrations over the dosing interval. |
Initial: 300 mg orally once daily; may increase by 300 mg/day every 2-3 days. Target dose: 400-800 mg/day for schizophrenia; 300-600 mg/day for bipolar depression; 400-800 mg/day for acute mania. Maximum: 800 mg/day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl 30-60 mL/min). For severe impairment (CrCl <30 mL/min), start at 50 mg/day and titrate slowly; maximum 300 mg/day. |
| Liver impairment | Child-Pugh Class A or B: Start at 50 mg/day and titrate cautiously. Child-Pugh Class C: Avoid use or start at very low doses (25-50 mg/day) with careful monitoring; maximum 200 mg/day. |
| Pediatric use | Adolescents (13-17 years): Schizophrenia – initial 50 mg/day; increase by 50-100 mg/day; target 400-800 mg/day. Bipolar mania (10-17 years): initial 50 mg/day; increase by 50-100 mg/day; target 400-600 mg/day. Weight-based not specified; use age-based dosing. |
| Geriatric use | Start at 50 mg/day (oral); increase by 50 mg/day every 1-2 days if tolerated; target 200-400 mg/day. Monitor for orthostatic hypotension, sedation, and QT prolongation. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SEROQUEL XR (SEROQUEL XR).
| Breastfeeding | Quetiapine is excreted into human breast milk in low concentrations. Milk-to-plasma ratio (M/P) is approximately 0.27. Consider monitoring infant for sedation and feeding difficulties. |
| Teratogenic Risk | Pregnancy Category C. First trimester: Limited human data; animal studies show fetal toxicity at high doses. Second and third trimesters: Risk of extrapyramidal symptoms and withdrawal in neonates following late gestational exposure. Overall risk-benefit assessment required. |
| Fetal Monitoring |
■ FDA Black Box Warning
Increased risk of mortality in elderly patients with dementia-related psychosis. Quetiapine is not approved for the treatment of dementia-related psychosis.
| Serious Effects |
["Hypersensitivity to quetiapine or any component of the formulation"]
| Precautions | ["Increased mortality in elderly patients with dementia-related psychosis","Suicidal thoughts and behaviors in children, adolescents, and young adults","Neuroleptic malignant syndrome (NMS)","Tardive dyskinesia","Hyperglycemia/diabetes mellitus","Hyperlipidemia","Weight gain","Leukopenia/neutropenia/agranulocytosis","Orthostatic hypotension/syncope","Seizures","Cataracts (lens changes)","QT prolongation","Dysphagia","Hypothyroidism","Hyperprolactinemia"] |
Loading safety data…
| Monitor maternal weight, glucose, lipids, and prolactin levels. Fetal monitoring: serial ultrasounds for growth restriction if significant weight gain or metabolic issues. Neonatal monitoring for extrapyramidal symptoms and withdrawal after delivery. |
| Fertility Effects | Quetiapine may cause hyperprolactinemia, which can lead to menstrual irregularities, galactorrhea, and reduced fertility. Normoprolactinemic state may be restored upon dose reduction or discontinuation. |