Overview
Olanzapine is an atypical antipsychotic medication used to treat schizophrenia and bipolar I disorder. It works by antagonizing multiple neurotransmitter receptors, particularly dopamine and serotonin receptors, to help regulate mood and thought processes. The medication requires careful monitoring due to potential metabolic side effects and risk of extrapyramidal symptoms.
Mechanism of Action
Olanzapine is a multi-receptor antagonist with high affinity for serotonin 5-HT2A/2C, dopamine D1-4, histamine H1, and adrenergic α1 receptors. It also has moderate affinity for serotonin 5-HT3 and muscarinic M1-5 receptors. This broad receptor antagonism modulates neurotransmitter activity in the central nervous system, particularly affecting dopaminergic and serotonergic pathways involved in psychosis and mood regulation.
Indications
- Treatment of schizophrenia
- Acute treatment of manic or mixed episodes associated with bipolar I disorder
- Maintenance treatment of bipolar I disorder
Common Doses
- 2.5 mg
- 5 mg
- 7.5 mg
- 10 mg
- 15 mg
- 20 mg
Dosage
Initial dose typically 5-10 mg once daily, with adjustments based on clinical response and tolerability. Maximum recommended dose is 20 mg daily. Dose adjustments may be needed for elderly patients, those with hepatic impairment, or when used in combination with other medications.
Contraindications
- Hypersensitivity to olanzapine or any component of the formulation
- When used in combination with fluoxetine (Symbyax), refer to Symbyax contraindications
Side Effects
- Weight gain
- Sedation/somnolence
- Dizziness
- Increased appetite
- Dry mouth
- Constipation
- Elevated liver enzymes
- Hyperglycemia
- Dyslipidemia
- Extrapyramidal symptoms
- Orthostatic hypotension
- When used with fluoxetine, refer to Symbyax adverse reactions
Interactions
- Enhanced CNS depression with alcohol and other CNS depressants
- Potential for increased orthostatic hypotension with antihypertensives
- Carbamazepine may decrease olanzapine concentrations
- Fluvoxamine may increase olanzapine concentrations
- Smoking may decrease olanzapine concentrations
- When used with fluoxetine, refer to Symbyax interactions
Counseling Points
- Take medication exactly as prescribed, typically once daily
- May cause drowsiness - avoid driving or operating machinery until effects are known
- Monitor for weight gain and report significant changes
- Rise slowly from sitting/lying position to prevent dizziness
- Avoid alcohol consumption
- Report any unusual movements, fever, or muscle stiffness immediately
- Regular monitoring of blood glucose and lipids may be required