Quetiapine is an atypical antipsychotic medication widely prescribed across the world for the treatment of serious mental health conditions including schizophrenia, bipolar disorder, and major depressive disorder (as adjunctive therapy). It belongs to the pharmacological class of second-generation antipsychotics, sometimes called serotonin–dopamine antagonists. Unlike first-generation or “typical” antipsychotics, quetiapine has a broader receptor activity profile, which contributes to its therapeutic effects but also its side-effect spectrum.
Quetiapine works primarily by antagonising multiple neurotransmitter receptors in the brain, especially serotonin type 2 (5-HT2A) and dopamine type 2 (D2) receptors. This dual action is thought to reduce psychotic symptoms such as hallucinations and delusions while causing fewer extrapyramidal side effects (movement disorders) than older agents. It also binds to histamine H1 receptors (causing sedation), muscarinic receptors (causing anticholinergic effects), and adrenergic receptors (leading to blood pressure changes). Its complex pharmacology explains its broad spectrum of action, as well as the wide range of possible adverse effects.
Quetiapine is available in both immediate-release and extended-release formulations, allowing for flexible dosing. It is typically taken once or twice daily, depending on indication and formulation. It was first approved in the late 1990s and has since become one of the most commonly used antipsychotics worldwide. Clinicians value its utility not only in psychotic disorders but also in mood disorders, particularly bipolar depression, where it has unique evidence among antipsychotics.
Despite its effectiveness, quetiapine must be used judiciously, with careful monitoring for metabolic side effects, sedation, and rare but serious risks such as neuroleptic malignant syndrome. It is generally not considered first-line for insomnia or anxiety alone, despite frequent off-label use in these contexts. Regulatory agencies emphasise that its use should be based on a comprehensive psychiatric evaluation and ongoing review.
Quetiapine therapy is usually long-term. Patients should not stop the medication abruptly, as this may lead to withdrawal symptoms or relapse. Instead, any dose adjustments should be made gradually under clinical supervision.
Most side effects can be managed by dose adjustment, switching formulations, or supportive measures. Lifestyle counselling is essential to counteract metabolic changes.
Before starting quetiapine, clinicians should assess personal and family history of diabetes, obesity, and cardiovascular disease. Informed consent about risks is essential.
Patients should provide a complete list of medications, supplements, and recreational substances to their healthcare provider. Regular review reduces risk of harmful interactions.
Overdose: Symptoms may include severe drowsiness, tachycardia, hypotension, delirium, seizures, and in rare cases coma. Management is supportive: airway protection, monitoring of vital signs, and cardiac monitoring for arrhythmias. Activated charcoal may be considered if ingestion is recent.
Accidental double dose: Usually not dangerous but may increase sedation or blood pressure changes. Patients should skip the next scheduled dose and resume as normal the following day. Medical advice should be sought if significant symptoms develop.
Missed dose: If remembered within a few hours, the dose can be taken. If close to the next scheduled dose, skip the missed dose and continue as normal. Double doses should be avoided.
Patients and families should be educated on recognising overdose signs and when to seek urgent help. Any suspected overdose should be assessed promptly in a medical facility.
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