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. |
| Molecular Weight | 383.56 |
| Action Class | Atypical Antipsychotic |
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 | Limited human data; animal studies show fetal harm. Potential risk of neural tube defects and low birth weight. Use only if benefit outweighs risk. |
| 2nd trimester | Risk of gestational diabetes, excessive maternal weight gain, and preterm labor. Monitor blood glucose and weight. |
| 3rd trimester | Risk of neonatal extrapyramidal symptoms, withdrawal, and respiratory distress after delivery. Consider tapering before delivery. |
Clinical note
Comprehensive clinical and safety monograph for SEROQUEL XR (SEROQUEL XR).
| Placental transfer | Crosses placenta; achieves fetal plasma concentrations approximately 50% of maternal levels. |
| Breastfeeding | Present in breast milk. Monitor infant for sedation, poor feeding, and weight loss. American Academy of Pediatrics recommends caution; consider benefits of breastfeeding vs. risk to infant. |
■ 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.
| Common Effects | Somnolence, Dizziness, Dry mouth, Constipation, Dyspepsia, Increased appetite, Weight gain, Asthenia, Headache, Orthostatic hypotension |
| Serious Effects | Increased mortality in elderly patients with dementia-related psychosis, Suicidal thoughts or behaviors, Neuroleptic malignant syndrome (NMS), Tardive dyskinesia, Metabolic changes: hyperglycemia, diabetes mellitus, dyslipidemia, weight gain, Orthostatic hypotension and syncope, Seizures, Leukopenia, neutropenia, agranulocytosis, QT prolongation, Cataracts |
History of hypersensitivity to quetiapine or any excipientConcomitant use with CYP3A4 inducers (e.g., carbamazepine, rifampin) reduces efficacy
| 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 |
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| Lactation Rating | L3 (Moderately Safe) |
| 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 | 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. |
| Food/Dietary | Avoid grapefruit and grapefruit juice, which can increase quetiapine levels. Taking with a high-fat meal may affect absorption; it is recommended to take it on an empty stomach or with a light meal. Alcohol should be avoided due to additive sedation and possible cognitive impairment. |
| Clinical Pearls | For bipolar depression, SEROQUEL XR is effective at doses of 300 mg once daily, but may cause more sedation, weight gain, and metabolic side effects than other mood stabilizers. Titrate gradually to minimize orthostatic hypotension and sedation. Monitor fasting glucose, lipids, and weight at baseline and periodically. Avoid use in elderly patients with dementia-related psychosis due to increased mortality risk. |
| Patient Advice | Take this medication once daily in the evening, without food or with a light meal, and swallow the tablets whole without crushing or chewing. · Drowsiness is common, especially during the first few weeks; avoid driving or operating heavy machinery until you know how the medicine affects you. · Do not drink alcohol or use grapefruit juice while on this medication as they may increase side effects. · Contact your doctor immediately if you experience symptoms of high blood sugar (excessive thirst, frequent urination, blurred vision) or neuroleptic malignant syndrome (fever, muscle rigidity, confusion). · Do not stop taking this medication abruptly as withdrawal symptoms may occur; consult your doctor for a gradual dose reduction. |