Olanzapine: Drug Information
1. Drug Name
Generic Name
Olanzapine
Brand Name(s)
- Pakistan: Zypadhera
- India: Oleanz, Symbyax (combination with fluoxetine)
- US: Zyprexa, Zyprexa Zydis, Symbyax
- UK: Zyprexa, Zyprexa Velotab
2. Pharmacological Class
Class
Atypical antipsychotic
Subclass
Thienobenzodiazepine
3. Mechanism of Action
Olanzapine works by antagonizing dopamine D2 and serotonin 5-HT2A receptors in the brain, reducing symptoms of psychosis and mood disorders. It also affects other neurotransmitter receptors like histamine, alpha-adrenergic, and muscarinic receptors.
4. Indications
Primary Indications
- Schizophrenia: Treatment of schizophrenia and maintenance therapy to prevent relapse.
- Bipolar Disorder: Acute treatment of manic or mixed episodes, and maintenance therapy for bipolar I disorder.
- Depression (as Symbyax): In combination with fluoxetine for treatment-resistant depression and depressive episodes associated with bipolar I disorder.
Off-label Uses
- Agitation in dementia
- Borderline personality disorder
- Post-traumatic stress disorder (PTSD)
5. Dosage and Administration
Standard Dosage
For schizophrenia:
- Initial: 5-10 mg once daily
- Maintenance: 10-20 mg/day
For bipolar disorder:
- Initial: 10-15 mg once daily
- Maintenance: 5-20 mg/day
For depression (Symbyax):
- Initial: 6 mg olanzapine/25 mg fluoxetine once daily
- Maintenance: 6-12 mg olanzapine/25-50 mg fluoxetine
Route of Administration
Oral (tablets, orally disintegrating tablets), Intramuscular (long-acting injectable)
Special Populations
- Pediatric: Safety and efficacy in children under 13 years of age have not been established.
- Geriatric: Use with caution due to increased risk of cerebrovascular adverse reactions.
6. Pharmacokinetics
Absorption
Well absorbed with peak plasma concentrations reached within 5-8 hours after oral administration.
Distribution
Widely distributed in the body. Approximately 93% bound to plasma proteins.
Metabolism
Metabolized primarily in the liver by CYP1A2 and CYP2D6 enzymes.
Excretion
Excreted mainly in urine (57%) and feces (30%).
Half-life
The elimination half-life ranges from 21 to 54 hours, depending on the individual's metabolism.
7. Contraindications
- Known hypersensitivity to olanzapine or any components of the formulation
- Severe CNS depression
- Narrow-angle glaucoma
8. Warnings and Precautions
- Increased mortality in elderly patients with dementia-related psychosis
- Neuroleptic malignant syndrome (NMS)
- Tardive dyskinesia
- Hyperglycemia and diabetes mellitus
- Orthostatic hypotension
9. Side Effects
Common Side Effects
- Weight gain
- Increased appetite
- Drowsiness
- Dizziness
Serious Side Effects
- Extrapyramidal symptoms (EPS)
- Hyperglycemia
- Seizures
10. Drug Interactions
Major Interactions
- Carbamazepine
- Fluvoxamine
Moderate Interactions
- Antihypertensive agents
- Diazepam
Minor Interactions
- Alcohol
- St. John's Wort
11. Pregnancy and Lactation
Pregnancy Category
Category C - Risk cannot be ruled out.
Breastfeeding Considerations
Not recommended during breastfeeding due to potential adverse effects on the infant.
12. Patient Counseling Information
- Take as directed and do not exceed prescribed dose.
- Avoid alcohol and be cautious with activities requiring mental alertness until the response to the medication is known.
- Monitor for signs of high blood sugar (e.g., increased thirst, urination) and report to the healthcare provider.
- Maintain a balanced diet and