olanzapine

General information

• Class: Antipsychotic
• Common US brands: ZYPREXA
• Typical dose range: Schizophrenia (adults): initiate 5–10 mg once daily; titrate by 5 mg increments at ≥24-hour intervals to 10–20 mg/day (max 20 mg).
• Long-acting injectable formulation available.
• Therapeutic drug monitoring not routinely recommended.
• Last reviewed: 2025-12-28

Dosing & forms

• Forms/strengths: Oral tablets: 2.5–20 mg; orally disintegrating tablets (Zyprexa Zydis): 5–20 mg.; Intramuscular injection: 10 mg vials for acute agitation.; Long-acting depot (Zyprexa Relprevv): 210 mg, 300 mg, 405 mg every 2–4 weeks.
• Frequency: Schizophrenia (adults): initiate 5–10 mg once daily; titrate by 5 mg increments at ≥24-hour intervals to 10–20 mg/day (max 20 mg).
• Typical range: Schizophrenia (adults): initiate 5–10 mg once daily; titrate by 5 mg increments at ≥24-hour intervals to 10–20 mg/day (max 20 mg).

Mechanism (brief)

Antagonist at serotonin 5‑HT2A and dopamine D2 receptors; strong H1 and muscarinic activity.

Metabolism & Half‑life

• Metabolism: CYP1A2, CYP2D6 (minor)
• Half‑life: Steady-state mean 30 h

Therapeutic Drug Monitoring (TDM)

Recommended: No

Long‑acting injectable (LAI)

Monitoring highlights

• Metabolic monitoring (weight/BMI, waist circumference, blood pressure, fasting glucose/A1c, lipids) at baseline and periodically (early and then ongoing) because weight and glycemic changes can occur quickly.
• Appetite changes, sedation, and falls risk—reassess driving and occupational safety after dose changes and when other CNS depressants are added.
• Smoking status and CYP1A2 modulators; reduce dose when smoking stops and reassess if smoking restarts or if CYP1A2 inhibitors are introduced.
• AIMS/EPS monitoring at routine intervals, especially in older adults and at higher doses (EPS risk is lower than FGAs but not zero).
• For depot olanzapine pamoate, adhere to REMS observation and PDSS counseling requirements, including post-injection monitoring and “no driving” instructions on injection day.

Sources

• ZYPREXA (olanzapine) label — DailyMed (2025)
• AGNP TDM Consensus — Pharmacopsychiatry (2018)
• The American Psychiatric Association Practice Guideline for the Treatment of Patients With Schizophrenia — American Psychiatric Association (2020)
• Effectiveness of antipsychotic drugs in patients with chronic schizophrenia — The New England Journal of Medicine (2005)
• The CANMAT and ISBD Guidelines for the Management of Patients With Bipolar Disorder: 2021 Update — Bipolar Disorders (2021)