Olanzapine is used for the acute and long-term treatment of schizophrenia and related psychotic disorders, particularly when positive symptoms (such as delusions, hallucinations, disorganized thinking, hostility, and suspiciousness) and/or negative symptoms (such as reduced emotional expression, social withdrawal, and reduced speech) are prominent. It is also indicated for the treatment of acute manic or mixed episodes in bipolar disorder, with or without psychotic features, and with or without rapid cycling.

Olanzapine is an atypical antipsychotic agent that acts on multiple neurotransmitter receptors, including serotonin (5HT2A/2C, 5HT3, 5HT6), dopamine (D1–D5), muscarinic (M1–M5), alpha-1 adrenergic, and histamine H1 receptors. Although its exact mechanism in schizophrenia is not fully understood, its therapeutic effect is thought to result mainly from combined dopamine and serotonin (5HT2) receptor antagonism. After oral administration, olanzapine is well absorbed and reaches peak plasma levels within 5 to 8 hours. Food does not significantly affect its absorption. It is non-mutagenic, non-clastogenic, and non-carcinogenic.

Schizophrenia, combination therapy for Mania, Bipolar Disorder: The initial dose is 5-10 mg once daily. Daily dosage may subsequently be adjusted on the basis of individual clinical status within the range of 5-20 mg daily. Dosage greater than 10 mg daily only after reassessment. Maximum dose is 20 mg daily.

Monotherapy for Mania: Initially 15 mg once daily. Daily dosage may subsequently be adjusted on the basis of individual clinical status within the range of 5-20 mg daily. Dosage greater than 15 mg only after reassessment. Maximum dose is 20 mg daily.

Olanzapine can be given without regard to meals. Gradual tapering of the dose should be considered while discontinuing Olanzapine.

Olanzapine may reduce the therapeutic effect of levodopa and dopamine agonists. Drugs that induce CYP1A2 or glucuronyl transferase enzymes, such as omeprazole and rifampicin, may increase the clearance of olanzapine, leading to reduced plasma levels. Inhibitors of CYP1A2 may decrease the elimination of olanzapine, increasing its concentration in the body. Carbamazepine can also increase the clearance of olanzapine. Concomitant use of activated charcoal may reduce the oral bioavailability of olanzapine by 50–60%. Caution is advised when olanzapine is used together with centrally acting drugs and alcohol.

Olanzapine is contraindicated in patients with known hypersensitivity to olanzapine or any of its ingredients. It is also contraindicated in patients at risk of narrow-angle glaucoma.

Very common side effects include somnolence (drowsiness) and weight gain. Other possible effects include increased appetite, elevated blood glucose, increased triglycerides, dizziness, akathisia, Parkinson-like symptoms, dyskinesia, orthostatic hypotension, mild anticholinergic effects such as constipation and dry mouth, asthenia, edema, and photosensitivity reactions.

Olanzapine should be used during pregnancy only if the potential benefits outweigh the potential risks to the fetus. Patients should inform their physician if they are pregnant or planning pregnancy during treatment. No confirmed evidence of teratogenicity has been reported. Breastfeeding is not recommended during olanzapine therapy.

Olanzapine should be used with caution in patients with a history of seizures or conditions that lower seizure threshold. Caution is also needed in patients with low white blood cell or neutrophil counts, bone marrow suppression, radiation or chemotherapy-related toxicity, hypereosinophilic conditions, hepatic impairment, and those taking hepatotoxic or QT-prolonging drugs, especially in elderly patients. Patients should be warned about operating machinery or driving.

Children: Olanzapine has not been studied in patients under 18 years of age.
Elderly patients (≥65 years): starting dose is 5 mg/day.
Patients with hepatic or renal impairment: starting dose is 5 mg/day.

Atypical neuroleptic drugs

Store below 30°C, protect from light and moisture. Keep out of reach of children.