Quetiapine is an atypical antipsychotic drug. It is widely prescribed for treating conditions like schizophrenia, bipolar disorder, and depression. Quetiapine is available in both immediate-release and extended-release formulations.
Mechanism of Action
Quetiapine performs its work by altering neurotransmitter activity in the brain. It affects the following receptors.
- Dopamine D2 receptors: Reduces psychotic symptoms.
- Serotonin 5-HT2A receptors: Stabilizes mood.
- Histamine receptors: Causes sedative effects.
- Alpha-1 adrenergic receptors: Contributes to sedation.
Indications or Uses
Quetiapine has following uses:
- Schizophrenia: It treats both acute and chronic forms.
- Bipolar disorder: Used in managing wild, depressive, and maintenance phases.
- Major depressive disorder: As an adjunct treatment with antidepressants.
- Generalized anxiety disorder: Off-label use for some patients.
Dosage Forms and Strengths
Quetiapine is available in various formulations:
- Tablets: 25 mg, 50 mg, 100 mg, 200 mg, 300 mg, 400 mg
- Extended-release tablets: 50 mg, 150 mg, 200 mg, 300 mg, 400 mg
The extended-release tablets are mostly taken once a day once daily, while the immediate-release tablets may require multiple daily doses.
Popular Brand Names of Quetiapine
| Brand Name | Manufacturer | Formulation | Strengths | Common Use |
| Seroquel | AstraZeneca | Oral tablets, extended-release | 25 mg, 50 mg, 100 mg, 200 mg, 400 mg | Schizophrenia, bipolar disorder |
| Seroquel XR | AstraZeneca | Extended-release tablets | 50 mg, 150 mg, 200 mg, 300 mg, 400 mg | Bipolar disorder, major depression |
| Quepin | Dr. Reddy’s Laboratories | Oral tablets, extended-release | 25 mg, 50 mg, 100 mg, 200 mg | Schizophrenia, mood stabilization |
| Zque | Zydus Cadila | Oral tablets | 25 mg, 50 mg, 100 mg | Schizophrenia, bipolar disorder |
| Quetapel | Hetero Healthcare | Oral tablets | 25 mg, 50 mg, 100 mg | Schizophrenia, bipolar disorder |
Side Effects of Quetiapine
Common side effects
- Sedation: Drowsiness or sleepiness.
- Weight gain: Especially with long-term use.
- Metabolic changes: Elevated blood sugar, cholesterol, and triglycerides.
- Dizziness: Especially when standing.
- Dry mouth: Unpleasant sensation.
- Extrapyramidal symptoms (EPS): Tremors, rigidity, or stiffness.
Serious side effects
- Neuroleptic malignant syndrome (NMS): A rare, life-threatening condition.
- Tardive dyskinesia: Irreversible involuntary movements.
- Cardiovascular issues: Prolonged QT interval can cause arrhythmias.
Precautions and Warnings
Consider these precautions while using quetiapine.
- Older age patients: Increased risk of death from cardiovascular issues, especially with dementia.
- Pregnancy: Use only if the benefit outweighs the risk. It can harm the fetus.
- Liver and kidney disease: Dose adjustments may be necessary.
- Addiction: Quetiapine is not physically addictive but may cause dependency with misuse.
Drug Interactions of Quetiapine
Quetiapine interacts with several medications.
- CNS depressants: Increased sedative effects when combined with drugs like benzodiazepines or alcohol.
- Antihypertensives: May enhance the blood-pressure-lowering effects.
- CYP3A4 inhibitors/inducers: Drugs like ketoconazole or carbamazepine can alter quetiapine metabolism.
Conclusion
Quetiapine is an effective antipsychotic used in treating conditions like schizophrenia and bipolar disorder. Its side effects are generally mild but should be monitored. It is important to tailor the dosage and formulation to the individual patient’s needs. Close monitoring is essential for ensuring safe and effective use.
References
- American Psychiatric Association. (2013). Diagnostic and Statistical Manual of Mental Disorders (5th ed.). American Psychiatric Publishing.
- Muench, J., & Hamer, A. M. (2010). Adverse effects of antipsychotic medications. American Family Physician, 81(5), 617-622.
- “Seroquel (Quetiapine) Drug Information”. Drugs.com. https://www.drugs.com/seroquel.html
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