Olanzapine is a second-generation (atypical) antipsychotic medication widely used in the treatment of schizophrenia, bipolar disorder, and related psychiatric conditions. It was first approved in the late 1990s and rapidly became a cornerstone of modern psychiatry due to its broad efficacy across psychotic and mood disorders. Unlike older typical antipsychotics that mainly target dopamine D2 receptors, olanzapine acts on a wide array of receptors, including serotonin (5-HT2A/2C), dopamine (D1–D4), histamine (H1), and muscarinic receptors. This multi-receptor profile helps reduce psychotic symptoms, improve mood, and stabilise behaviour, while reducing the risk of certain side effects like extrapyramidal symptoms (movement disorders) that were common with first-generation antipsychotics.
Olanzapine’s therapeutic impact is notable in both acute management of psychosis and long-term relapse prevention. Its calming and mood-stabilising effects make it especially valuable in patients with agitation, aggression, or mixed mood and psychotic features. Clinical guidelines frequently recommend olanzapine as one of the first-line atypical antipsychotics, particularly in cases where sedation and weight gain are considered manageable or where rapid symptom control is a priority. It is available in oral tablets, orally disintegrating tablets (ODT), intramuscular injection for acute agitation, and long-acting injectable formulations for maintenance therapy.
Despite its benefits, olanzapine has a significant side-effect profile, most notably metabolic effects such as weight gain, increased blood glucose, and dyslipidaemia. These risks necessitate close monitoring, lifestyle counselling, and sometimes combination therapy with metabolic-protective agents. Nevertheless, its effectiveness, tolerability in terms of movement side effects, and broad-spectrum activity ensure that olanzapine remains one of the most prescribed atypical antipsychotics worldwide.
In clinical practice, olanzapine is valued for its versatility across psychotic and mood-related conditions. Its use requires balancing benefits in symptom control with careful monitoring of metabolic risks.
Patients should be educated about early warning signs such as excessive thirst, frequent urination, persistent fatigue, unexplained fever, or muscle stiffness, and instructed to seek medical care promptly if these arise.
Inform all healthcare providers about olanzapine therapy before surgeries or when prescribing new medications to reduce risks of drug interactions and complications.
Olanzapine is metabolised mainly by CYP1A2 and to a lesser extent by CYP2D6. Key interactions include:
Patients should be encouraged to share a complete medication and supplement list with their prescribers to avoid harmful interactions.
Overdose: Symptoms include profound sedation, tachycardia, hypotension, anticholinergic effects (dry mouth, dilated pupils, urinary retention), and in severe cases, respiratory depression or cardiac arrhythmias. Fatal outcomes are rare with supportive treatment but possible at very high doses. Management includes airway support, intravenous fluids, monitoring of cardiac rhythm, and symptomatic treatment. Activated charcoal may reduce absorption if given promptly after ingestion.
Accidental double dose: Usually results in increased sedation and dizziness. Patients should avoid driving or hazardous tasks and contact their clinician for guidance.
Missed dose: Take as soon as remembered unless close to the next scheduled dose. Do not double doses. Consistency is important for relapse prevention.
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