What is the recommended dose of olanzapine (atypical antipsychotic) for adults with schizophrenia or bipolar disorder, considering factors such as age, medical history, and potential side effects?

Olanzapine Dosing for Schizophrenia and Bipolar Disorder

For adults with schizophrenia, start olanzapine at 5-10 mg orally once daily with a target dose of 10 mg/day within several days; for bipolar I disorder manic or mixed episodes, start at 10-15 mg once daily. 1

Adult Dosing by Indication

Schizophrenia

• Initial dose: 5-10 mg orally once daily, targeting 10 mg/day within several days 1
• Maintenance range: 10-15 mg/day demonstrated efficacy in clinical trials, though doses above 10 mg/day were not more efficacious than 10 mg/day 1
• Maximum dose: 20 mg/day; olanzapine is not indicated for doses above this threshold 1
• Dose adjustments: Should occur at intervals of not less than 1 week, as steady-state concentrations require approximately one week to achieve 2, 1
• Dose increments: 5 mg adjustments are recommended when changes are necessary 1

Bipolar I Disorder (Manic or Mixed Episodes)

• Monotherapy: Start at 10-15 mg once daily 1
• With lithium or valproate: Start at 10 mg once daily 2
• Maintenance treatment: Effective doses range from 10-20 mg/day 3

Acute Agitation (Intramuscular)

• Standard IM dose: 10 mg (or 5-7.5 mg when clinically warranted) 2, 1
• Dosing frequency: Maximum 3 doses given 2-4 hours apart 1
• Important: Assess for orthostatic hypotension prior to subsequent dosing 1

Special Population Dosing

Elderly Patients

• Starting dose: 2.5-5 mg once daily at bedtime 2, 4
• Maximum dose: 10 mg/day; avoid exceeding this without compelling clinical justification 2
• Target range: Most elderly patients respond adequately to 5-10 mg/day 2
• Critical warning: FDA black box warning for increased mortality in elderly patients with dementia-related psychosis 2, 1

Hepatic Impairment

• Starting dose: 2.5 mg daily to minimize risk of toxicity 2, 4, 3

Debilitated Patients or Those Predisposed to Hypotension

• Starting dose: 5 mg in patients who are debilitated, have predisposition to hypotensive reactions, or exhibit factors resulting in slower metabolism (e.g., nonsmoking females ≥65 years) 1
• Dose escalation: Perform with caution in these patients 1

Adolescents (Ages 13-17)

Schizophrenia

• Starting dose: 2.5-5 mg once daily 1
• Target dose: 10 mg/day 2, 1
• Dose adjustments: Increments/decrements of 2.5 or 5 mg 1
• Maximum evaluated dose: 20 mg/day 1

Bipolar I Disorder (Manic or Mixed Episodes)

• Starting dose: 2.5-5 mg once daily 2, 1
• Target dose: 10 mg/day 2
• Important consideration: The increased potential for weight gain and dyslipidemia in adolescents compared with adults may lead clinicians to consider prescribing other drugs first 1

Critical Safety Monitoring

Metabolic Effects

• Weight gain: Monitor closely, particularly in adolescents who experience greater increases than adults 5
• Lipid abnormalities: Monitor blood lipids regularly 5
• Glucose metabolism: Screen for hyperglycemia 1

Cardiovascular Monitoring

• Orthostatic hypotension: Monitor especially in elderly and debilitated patients 2, 3
• Assess before each IM dose when treating acute agitation 1

Drug Interactions - Critical Warning

• Benzodiazepine combination: Use extreme caution due to risk of oversedation and respiratory depression 2, 4, 3
• Fatalities reported: With concurrent use of benzodiazepines and high-dose olanzapine 2, 4, 3
• Fluvoxamine: Significantly increases olanzapine plasma concentrations; dose reduction may be necessary 6
• Smoking status: Smokers have significantly lower dose-corrected plasma levels than non-smokers 6

Additional Monitoring

• Sedation: Common adverse effect, particularly pronounced in elderly females 2
• Prolactin levels: Monitor, especially in adolescents 5
• Liver transaminases: Monitor, particularly in adolescents who show greater increases than adults 5
• Extrapyramidal symptoms: Lower risk than typical antipsychotics, but monitor nonetheless 2

Administration Considerations

• Timing: Can be given without regard to meals 1
• Formulations: Available as oral tablets, orally disintegrating tablets (ODT), and intramuscular injection 2, 1
• Steady-state: Achieved in approximately one week in typical patients 1

Common Pitfalls to Avoid

• Rapid dose escalation: Wait at least 1 week between dose adjustments to allow steady-state achievement 2, 1
• Exceeding 20 mg/day without justification: Doses above 10 mg/day were not more efficacious in trials, and doses above 20 mg/day are not indicated 1
• Combining with benzodiazepines: Exercise extreme caution due to fatality reports 2, 4, 3
• Inadequate monitoring in adolescents: This population experiences greater metabolic adverse effects than adults 5
• Using in elderly with dementia: Not approved for dementia-related psychosis due to increased mortality risk 1