Olanzapina (Olanzapine)

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

• Schizophrenia: helps control delusions, hallucinations and thought disorder.
• Bipolar I disorder (manic episodes): reduces manic symptoms and stabilises mood.
• Schizoaffective disorder: alleviates both psychotic and mood components.
• Maintenance therapy for schizophrenia: helps prevent relapse after acute treatment.
• Adjunctive treatment in major depressive disorder with psychotic features: augments antidepressant response.

• Olanzapine exerts its antipsychotic effect by antagonising dopamine D2 receptors and serotonin 5‑HT2A receptors, with additional activity at histamine H1, muscarinic and adrenergic receptors. This receptor profile reduces dopaminergic neurotransmission in mesolimbic pathways while modulating serotonergic tone, contributing to symptom control in psychotic and mood disorders.

Olanzapine may cause a range of adverse reactions, most of which are dose‑dependent and reversible upon discontinuation.

Common Side Effects

• Weight gain: increased appetite and caloric intake.
• Sedation: drowsiness or feeling of being overly sleepy.
• Dry mouth: reduced salivary flow.
• Constipation: slowed gastrointestinal motility.
• Orthostatic hypotension: drop in blood pressure upon standing.
• Elevated prolactin: mild hormonal changes.

Serious or Rare Side Effects

• Neuroleptic malignant syndrome: high fever, muscle rigidity, autonomic instability.
• Tardive dyskinesia: involuntary, repetitive movements, often of the face.
• Severe hyperglycaemia or new‑onset diabetes mellitus.
• Agranulocytosis: dangerously low white‑blood cell count.
• Myocardial infarction or other cardiac events.
• Seizures: especially in patients with prior seizure history.

When prescribing Olanzapine, clinicians should evaluate patient history and monitor for specific safety concerns.

• Metabolic monitoring: regularly check weight, fasting glucose and lipid profile.
• Cardiovascular assessment: monitor blood pressure and heart rate, especially at treatment initiation.
• CNS effects: advise patients about sedation and avoid operating heavy machinery until they know how the drug affects them.
• Pregnancy and lactation: use only if the potential benefit outweighs risk; discuss with obstetric specialist.
• Elderly patients with dementia: avoid due to increased risk of mortality.
• Store at ambient temperature: keep in original container, protect from moisture and direct sunlight.

Olanzapine can interact with several drug classes, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Strong CYP1A2 inhibitors (e.g., fluvoxamine): may increase olanzapine plasma levels and risk of toxicity.
• CNS depressants: additive sedation with alcohol, benzodiazepines or opio opioids.
• Anticholinergic agents: may exacerbate dry mouth and constipation.

Moderate Interactions (Monitor Closely):\n- CYP3A4 inducers (e.g., carbamazepine, rifampicin): may reduce olanzapine concentrations.

• Smoking: induces CYP1A2 and can lower drug exposure.
• QT‑prolonging drugs: combined use may increase risk of cardiac arrhythmias.