Generic
Quetiapine
52 brands available in the market
At a glance
Quetiapine is an atypical antipsychotic used for schizophrenia, bipolar disorder (manic and depressive episodes), and major depressive disorder. It acts as an antagonist at multiple neurotransmitter receptors in the brain.
Description
Quetiapine is an atypical psychotropic agent belonging to the dibenzothiazepine derivatives class. It is an antagonist at multiple neurotransmitter receptors: serotonin 5HT1A and 5HT2, dopamine D1 and D2, histamine H1, and adrenergic α1 and α2 receptors. It has no appreciable affinity at cholinergic muscarinic and benzodiazepine receptors.
Indications
- Schizophrenia (acute and chronic psychoses)
- Bipolar disorder (manic episodes)
- Bipolar disorder (depressive episodes)
- Maintenance treatment of bipolar I disorder
- Major depressive disorder (adjunctive therapy)
Therapeutic class
Atypical neuroleptic drugs
Pharmacological class
Dibenzothiazepine (Atypical Antipsychotic)
Pharmacology
Quetiapine blocks serotonin 5HT2, dopamine D2, histamine H1, and adrenergic α1/α2 receptors in the brain. Efficacy in schizophrenia is mediated through a combination of dopamine D2 and serotonin 5HT2 antagonism. Histamine H1 antagonism may explain somnolence, and α1 antagonism may explain orthostatic hypotension.
Mechanism of action
Controls schizophrenia and bipolar disorder symptoms by blocking serotonin and dopamine receptors.
Dosage
Adult Dose (Oral):
- Schizophrenia (IR): Day 1: 50 mg/day; Days 2-3: increase by 25-50 mg; Day 4: 300-400 mg; maintenance 150-750 mg/day
- Schizophrenia (XR): Day 1: 300 mg/day; Day 2+: increase by 300 mg/day; maintenance 400-800 mg/day
- Bipolar mania (IR): Day 1: 100 mg/day; Day 2: 200; Day 3: 300; Day 4: 400; Day 6: up to 800 mg/day; maintenance 400-800 mg/day
- Bipolar mania (XR): Day 1: 300 mg/day; Day 2: 600 mg/day; maintenance 400-800 mg/day
- Bipolar depression: Day 1: 50 mg at bedtime; Day 2: 100; Day 3: 200; Day 4: 300 mg at bedtime (maintenance)
- MDD (adjunct): Days 1-2: 50 mg in evening; Day 3: 150 mg in evening; maintenance 150-300 mg/day
- Elderly: Slower dose titration, lower therapeutic dose
- Hepatic impairment: 25 mg/day initially; increase by 25-50 mg
Administration
- May be taken with or without food; take at a fixed time
- Swallow tablet whole; do not chew, crush, or break
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Side Effects:
- Somnolence
- Dizziness
- Dry mouth
- Weight gain
- Increased serum triglycerides
- Increased total cholesterol (LDL)
- Decreased HDL cholesterol
- Decreased hemoglobin
- Extrapyramidal symptoms
- Akathisia
- Dystonia
- Parkinsonism
Precautions & warnings
- May affect driving ability; do not drive if drowsy or dizzy
- Discontinue if Neuroleptic Malignant Syndrome (fever, muscle rigidity, altered consciousness) occurs
- Rise slowly to avoid orthostatic hypotension
- May cause weight gain, increased blood sugar and cholesterol; monitor regularly
- Do not stop abruptly
- Risk of suicidal thoughts or behavior; monitor
Contraindications
- Hypersensitivity to quetiapine or any ingredient
- Severe CNS depression
- Bone marrow suppression
- Coma
Drug interactions
- Alcohol: Increased risk of drowsiness and postural hypotension
- CYP3A4 inducers (phenytoin, carbamazepine): Decreased plasma levels
- CYP3A4 inhibitors (ketoconazole, erythromycin): Increased plasma levels
- Thioridazine, carbamazepine: Increased quetiapine clearance
Food interactions
Alcohol consumption with Quetiapine is unsafe.
Use in pregnancy
Use in Pregnancy: May be unsafe during pregnancy; animal studies have shown harmful effects; use only if clearly needed.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Probably unsafe; limited human data suggests drug may pass into breast milk; avoid breastfeeding.
Pediatric use
Not indicated for use in children and adolescents below 18 years.
Geriatric use
Elderly patients require slower dose titration and lower therapeutic dose; plasma clearance reduced by 30-50%.
Renal / hepatic impairment
Renal Impairment: Safe in kidney disease; dose adjustment may not be needed; consult your doctor.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed (25 mg/day initially); consult your doctor.
Overdose effects
Overdose (up to 30 g reported): Drowsiness, tachycardia, hypotension, QT prolongation; no specific antidote; airway maintenance, oxygenation, cardiovascular monitoring; refractory hypotension: IV fluids and sympathomimetics (avoid adrenaline and dopamine).
Storage conditions
Keep out of sight and reach of children; do not use after expiry date; store in a cool and dry place away from light.
Chemical structure
Quetiapine