Kventiax (Quetiapine)

Quetiapine is used to treat psychiatric disorders that involve dysregulation of dopamine and serotonin pathways.

• Schizophrenia: reduces psychotic symptoms such as hallucinations, delusions, and thought disorder.
• Bipolar disorder: stabilizes mood during manic and depressive episodes, decreasing frequency and severity of mood swings.
• Major depressive disorder (adjunctive): enhances antidepressant response when added to standard antidepressant therapy in adults.

• Quetiapine acts as an antagonist at serotonin 5‑HT2A and dopamine D2 receptors, which moderates psychotic and mood symptoms. It also blocks histamine H1, adrenergic α1, and serotonin 5‑HT1A receptors, contributing to its sedative, antihistaminic, and anxiolytic properties. The combined receptor profile leads to modulation of neurotransmission in cortical and limbic regions, helping to restore balance in patients with schizophrenia, bipolar disorder, and major depressive disorder.

Quetiapine may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Drowsiness: feeling of sleepiness or fatigue.
• Dry mouth: reduced salivation leading to throat discomfort.
• Orthostatic hypotension: drop in blood pressure upon standing.
• Dizziness: light‑headed sensation, especially when changing posture.
• Weight gain: increase in body weight over the course of treatment.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: rare life‑threatening reaction with fever and muscle rigidity.
• Agranulocytosis: severe reduction in white blood cells, increasing infection risk.
• Tardive dyskinesia: involuntary, repetitive movements, often of the face.

When prescribing quetiapine, clinicians should consider several precautionary measures to ensure patient safety.

• Monitor blood pressure: watch for orthostatic hypotension, especially during dose initiation.
• Assess metabolic parameters: regularly check weight, glucose, and lipid levels.
• Evaluate for suicidal ideation: screen patients for worsening depression or suicidal thoughts.
• Use caution in hepatic impairment: adjust dosing if liver function is compromised.
• Avoid abrupt discontinuation: taper the dose to prevent withdrawal symptoms.
• Store at room temperature: keep tablets in the original container, protect from moisture and light.

Quetiapine can interact with other medicines, altering its effectiveness or safety profile.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase quetiapine plasma levels.
• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce quetiapine effectiveness.
• CNS depressants (e.g., alcohol, benzodiazepines): can enhance sedative effects and respiratory depression.

Moderate Interactions (Monitor Closely)

• Antihypertensive agents: additive blood‑pressure lowering effect.
• Other antipsychotics or antidepressants: may increase risk of QT prolongation or serotonin syndrome.
• Antihistamines: may intensify sedation.