Olanzapine
Class: atypical antipsychotic
Indications (NB some may be unlicensed): acute and chronic psychoses including schizophrenia, bipolar disorder, acute mania, nausea and vomiting in palliative care, delirium
Contraindications/cautions: liver dysfunction, cardiovascular and cerebrovascular disease, hypotension, seizures, blood disorders, renal dysfunction, prostatic hypertrophy, paralytic ileus, bone marrow depression, diabetes, narrow angle glaucoma, hypercholesteraemia, Parkinson’s disease, DLB
Adverse reactions: common: drowsiness, weight gain, dizziness, hallucinations, akathisia and other extrapyramidal side effects, elevated blood glucose and triglycerides, chest pain, oedema, constipation, dry mouth; less common: angioedema, urticaria, diabetic coma, hepatitis, pancreatitis, priapism, tardive dyskinesia, neuroleptic malignant syndrome, blood disorders, hypotension, mania, seizures
Metabolism/clearance: metabolised mainly in the liver by the metabolising enzymes CYP1A2 to inactive metabolites which are partially excreted by the kidneys; use lower doses in renal & hepatic disease
Interactions:
- increased clinical effect/toxicity of olanzapine (due to increased blood concentrations) may occur with some CYP metabolising enzyme inhibitors (see above) e.g. ciprofloxacin, ketoconazole
- decreased clinical effect/toxicity of olanzapine (due to decreased blood concentrations) may occur with some CYP metabolism enzyme inducers (see above) e.g. broccoli-like vegetables, smoking, phenobarbitone, phenytoin, rifampicin
- possible increase risk of extrapyramidal effects with dopamine antagonists e.g. metoclopramide
- additive hypotension with antihypertensives e.g. propranolol
- additive CNS effects with other CNS depressants e.g. benzodiazepines (e.g. lorazepam), phenothiazines (e.g. chlorpromazine), opioids, alcohol
| Dosing: | |
|---|---|
| oral tabs/disp tabs: | 2.5 to 5 mg daily at bedtime; may be increased if required in steps of 2.5 to 10 mg daily at bedtime – if 10 mg daily ineffective seek palliative care specialist advice |
| subcut: | inj available but recommended for im use only |
| rectal: | not available |
Syringe driver: not available
Mechanism of action: Olanzapine, a second generation (atypical) antipsychotic, acts as an antagonist at dopamine (D1-5), serotonin (5-HT 2 , 5-HT 3 , 5-HT 6 ), histamine-1, α 1 -adrenergic, and muscarinic (M1-5) receptors with varying affinity
Notes:
- lower potential for neurological adverse effects than conventional antipsychotics
- can be used in acute delirium and behavioural disturbances associated with brain tumours
- available in oro-dispersable tablets