Kvelux Sr (Quetiapine)

Quetiapine is an atypical antipsychotic that modulates dopamine and serotonin pathways in several psychiatric conditions.

• Schizophrenia: reduces psychotic symptoms such as hallucinations and delusions.
• Bipolar disorder (manic and depressive episodes): stabilises mood and prevents relapse.
• Major depressive disorder (adjunct therapy): enhances antidepressant response when added to standard treatment.

• Quetiapine acts as an antagonist at serotonin 5‑HT2A, dopamine D2, histamine H1 and adrenergic α1 receptors while providing partial agonism at 5‑HT1A receptors. This receptor profile leads to modulation of dopaminergic and serotonergic neurotransmission, contributing to antipsychotic and mood‑stabilising effects.

Quetiapine may cause a range of adverse reactions that vary in frequency and severity.

Common Side Effects

• Drowsiness: feeling unusually sleepy or fatigued.
• Dry mouth: reduced salivation leading to discomfort.
• Constipation: infrequent or difficult bowel movements.
• Weight gain: increase in body weight over time.
• Orthostatic hypotension: dizziness upon standing.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: life‑threatening reaction with fever and muscle rigidity.
• Tardive dyskinesia: involuntary, repetitive movements.
• Agranulocytosis: severe reduction in white blood cells.
• Suicidal thoughts: emergence or worsening of suicidal ideation.

Before initiating therapy, clinicians should evaluate patient history and monitor for specific risks.

• Cardiovascular assessment: check for orthostatic hypotension and heart rate changes.
• Metabolic monitoring: track weight, glucose and lipid levels regularly.
• Hepatic function: assess liver enzymes in patients with liver disease.
• Pregnancy and lactation: avoid unless benefits clearly outweigh potential risks.
• Elderly patients: start at low dose and titrate slowly due to increased sensitivity.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Quetiapine can interact with several drug classes, requiring careful management. Major Interactions (Avoid):\n- Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): may markedly increase quetiapine plasma levels.

• CNS depressants (e.g., benzodiazepines, opioids): can enhance sedation and respiratory depression.
• Antihypertensive agents: additive effect on blood pressure lowering.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce therapeutic effect.
• Anticholinergic drugs: may exacerbate dry mouth and constipation.
• Lithium: concurrent use may increase risk of neurotoxicity.