olanzapine: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
olanzapine: clinical details
Prescribing considerations
- Assess metabolic, cardiovascular, thromboembolic, seizure, hepatic and anticholinergic risk before prescribing.
- Olanzapine is not recommended for dementia-related psychosis or behavioural disturbance because mortality and cerebrovascular events were increased in trials.
- It is not recommended for dopamine-agonist-associated psychosis in Parkinson’s disease because Parkinsonian symptoms and hallucinations may worsen.
- Review treatment after changes in smoking status or when CYP1A2 inhibitors or inducers are introduced or withdrawn.
- For intramuscular use, assess haemodynamic stability, recent sedatives and cardiorespiratory risk; closely observe blood pressure, pulse, respiration and consciousness after administration.
Contraindications and cautions
- Hypersensitivity to olanzapine or a formulation excipient.
- Known risk of narrow-angle glaucoma.
- The intramuscular product should not be administered in unstable medical conditions such as severe hypotension, marked bradycardia, acute myocardial infarction, unstable angina, sick sinus syndrome or immediately following cardiac surgery.
Monitoring
- Record and follow weight and other clinically appropriate measures of adiposity.
- Check glycaemic status and lipids before and during treatment; monitor diabetes more closely.
- Assess blood pressure, postural symptoms, extrapyramidal effects and signs of tardive dyskinesia.
- Consider liver tests, blood counts and prolactin assessment according to symptoms and individual risk.
- Monitor for sedation, falls, constipation, urinary retention, seizures and venous thromboembolism risk.
- After intramuscular administration, monitor haemodynamic and respiratory status and level of consciousness.
Clinical pharmacology
Olanzapine is an antipsychotic, antimanic and mood-stabilising agent with antagonism across serotonin, dopamine, histamine, muscarinic and alpha-adrenergic receptors. Oral absorption is unaffected by food. Hepatic metabolism includes CYP1A2 and CYP2D6 pathways, with the parent compound providing the main pharmacological activity.
Formulation and product differences
- Coated tablets contain lactose and are swallowed with water.
- The orodispersible tablet is fragile, contains aspartame and parahydroxybenzoates, disperses rapidly in saliva and is bioequivalent to the coated tablet.
- The powder for solution produces an immediate-release intramuscular injection for acute agitation when oral treatment is inappropriate; it is not for intravenous or subcutaneous administration.
olanzapine preparations and strengths
Dispersible tablet
Route: Oral
Strengths: 5 mg, 10 mg, 15 mg, 20 mg
Tablet
Route: Oral
Strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 15 mg, 20 mg
olanzapine interactions
Tell the prescriber or pharmacist about all medicines, supplements, alcohol use and changes in smoking.
Fluvoxamine or ciprofloxacin
CYP1A2 inhibition can increase olanzapine exposure and adverse effects, requiring clinical review.
Carbamazepine
It can increase olanzapine metabolism and reduce exposure, so clinical response should be reviewed.
Tobacco smoke
Smoking can increase olanzapine clearance; starting or stopping smoking may alter exposure and warrants prescriber review.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.