Kwetaplex Xr (Quetiapine)

Quetiapine is an atypical antipsychotic that modulates neurotransmitter activity in several psychiatric conditions.

• Schizophrenia: helps reduce hallucinations, delusions and thought disorder.
• Bipolar disorder: stabilises mood and prevents manic or depressive episodes.
• Major depressive disorder (adjunct): enhances antidepressant response when added to standard therapy.

• Quetiapine acts as an antagonist at multiple neurotransmitter receptors, notably serotonin 5‑HT2A and dopamine D2 receptors, while also blocking histamine H1 and adrenergic α1 receptors. This receptor profile reduces dopaminergic and serotonergic over‑activity, contributing to antipsychotic and mood‑stabilising effects.

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

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: drop in blood pressure upon standing.
• Dizziness: sensation of light‑headedness.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: rare but life‑threatening reaction with fever and muscle rigidity.
• Tardive dyskinesia: persistent involuntary movements.
• Seizures: increased risk in susceptible individuals.
• Suicidal thoughts: emergence or worsening of suicidal ideation.
• Severe allergic reactions: rash, swelling, or breathing difficulty.

Before prescribing quetiapine, clinicians should consider several safety aspects.

• Cardiovascular monitoring: assess for orthostatic hypotension and heart rate changes.
• Metabolic assessment: monitor weight, glucose and lipid levels regularly.
• CNS effects: advise patients about sedation and impaired alertness, especially when driving.
• Hepatic/renal function: adjust use in patients with significant liver or kidney impairment.
• Pregnancy and lactation: evaluate risk‑benefit ratio; use only if clearly needed.
• 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, altering its efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin): may increase quetiapine plasma levels and toxicity.
• CNS depressants (e.g., benzodiazepines, opioids): additive sedation and respiratory depression.
• Antihypertensive agents: risk of exaggerated hypotension.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce quetiapine effectiveness.
• Anticholinergic drugs: may worsen dry mouth and constipation.
• Lithium: combined use may increase risk of neurotoxicity.