Kventiax Sr (Quetiapine)

Quetiapine is an atypical antipsychotic that modulates neurotransmitter activity across psychotic and mood disorder pathways.

• Schizophrenia: reduces positive and negative symptoms, improving overall functioning.
• Bipolar disorder (manic episodes): stabilizes mood and decreases the frequency and severity of manic episodes.
• Major depressive disorder (adjunct therapy): enhances antidepressant response when added to standard treatment regimens.

• Quetiapine exerts its therapeutic effect by antagonizing multiple neurotransmitter receptors, notably serotonin 5‑HT₂A and dopamine D₂ receptors, while also blocking histamine H₁ and adrenergic α₁ receptors. This broad receptor profile reduces dopaminergic overactivity and modulates serotonergic transmission, leading to antipsychotic, mood‑stabilising, and anxiolytic actions. The combined antagonism also influences glutamate and acetylcholine pathways, contributing to its efficacy in diverse psychiatric conditions.

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

Common Side Effects

• Drowsiness: feeling of sleepiness or fatigue.
• Dry mouth: reduced salivation causing discomfort.
• Constipation: infrequent bowel movements.
• Weight gain: gradual increase in body weight.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: rare but life‑threatening reaction with fever, muscle rigidity, and autonomic instability.
• Tardive dyskinesia: persistent involuntary movements, especially of the face and tongue.
• Suicidal thoughts: emergence or worsening of suicidal ideation in vulnerable patients.

When prescribing Kventiax Sr, clinicians should observe several precautionary measures to ensure patient safety.

• Cardiovascular assessment: monitor blood pressure and heart rate, especially in patients prone to orthostatic hypotension.
• Metabolic monitoring: regularly check glucose, lipid profile, and body weight during treatment.
• CNS depression: advise patients to avoid operating machinery until they know how the drug affects them.
• Pregnancy and lactation: use only if potential benefits outweigh uncertain risks, as data are limited.
• Discontinuation strategy: taper the dose gradually under medical supervision to reduce withdrawal or relapse.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture and light.

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

Major Interactions (Avoid)

• CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may markedly increase quetiapine plasma concentrations.
• CNS depressants (e.g., alcohol, benzodiazepines): can enhance sedation and respiratory depression.
• Antihypertensive agents: additive risk of orthostatic hypotension and blood pressure lowering.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers (e.g., rifampin, carbamazepine): may reduce quetiapine exposure and efficacy.
• Anticholinergic drugs: combined use may increase anticholinergic burden, worsening dry mouth or constipation.
• Lithium: concurrent therapy may raise the risk of neurotoxicity; monitor serum levels closely.