Ketilept Prolong (Quetiapine Fumarate)

Quetiapine fumarate is an atypical antipsychotic that modulates neurotransmitter activity in psychotic and mood disorders.

• Schizophrenia: reduces delusions, hallucinations and other positive psychotic symptoms.
• Bipolar disorder (manic episodes): stabilises mood and diminishes the severity of manic swings.
• Major depressive disorder (adjunct): enhances the therapeutic response when added to standard antidepressant regimens.

• Quetiapine fumarate acts as an antagonist at serotonin 5‑HT2A, dopamine D2, histamine H1 and adrenergic α1 receptors. By blocking D2 receptors it reduces dopaminergic hyperactivity linked to psychosis, while 5‑HT2A antagonism improves mood and cognition. Additional antihistaminic and anti‑adrenergic activity contributes to its sedative and anxiolytic properties, resulting in overall modulation of neurotransmission across multiple pathways.

Quetiapine fumarate may be associated with a range of adverse reactions, varying in frequency and severity.

Common Side Effects

• Drowsiness: feeling of sleepiness or reduced alertness.
• Dry mouth: decreased salivation leading to oral discomfort.
• Constipation: infrequent bowel movements or hard stools.
• Weight gain: increase in body weight over time.
• Orthostatic hypotension: drop in blood pressure upon standing causing dizziness.
• Elevated cholesterol: rise in blood lipid levels.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: rare but life‑threatening reaction with fever and muscle rigidity.
• Agranulocytosis: severe reduction in white blood cells increasing infection risk.
• Tardive dyskinesia: persistent involuntary movements, especially of the face.
• Suicidal thoughts: emergence or worsening of suicidal ideation.
• Severe allergic reaction: rash, swelling, or anaphylaxis.

When prescribing quetiapine fumarate, clinicians should consider several precautionary measures to ensure safe use.

• Dose titration: start low and increase gradually to minimise side‑effects.
• Cardiovascular monitoring: assess blood pressure and heart rate, especially for orthostatic changes.
• Metabolic screening: regularly check weight, glucose and lipid profiles.
• Psychiatric assessment: monitor for worsening depression or emergence of suicidal thoughts.
• Pregnancy and lactation: avoid use unless benefits outweigh potential risks, as safety data are limited.
• Store at ambient temperature: keep below 25 °C in the original container, protect from moisture and light.

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

Major Interactions (Avoid)

• CYP3A4 inhibitors: strong inhibitors such as ketoconazole may increase quetiapine levels, raising toxicity risk.
• CNS depressants: concurrent use with alcohol, benzodiazepines or opioids can enhance sedation and respiratory depression.

Moderate Interactions (Monitor Closely)

• CYP3A4 inducers: agents like rifampin may lower quetiapine concentrations, reducing effectiveness.
• Antihypertensives: additive blood‑pressure lowering may cause pronounced hypotension.
• Anticholinergic drugs: may exacerbate dry mouth and constipation.
• Antidepressants (e.g., SSRIs): monitor for additive serotonergic effects.