Olanzapine Dosage Recommendations
The recommended starting dose of olanzapine for adults is 5-10 mg orally once daily, with a target dose of 10 mg/day for schizophrenia and bipolar disorder, and doses can be adjusted within the range of 5-20 mg/day based on clinical response. 1
Standard Adult Dosing
Schizophrenia
- Initial dose: 5-10 mg once daily 1
- Target dose: 10 mg/day 1
- Maintenance range: 5-20 mg/day 1
- Doses above 10 mg/day should only be considered after clinical assessment 1
- Safety and efficacy of doses above 20 mg/day have not been established 1
Bipolar I Disorder (Acute Mania)
- Initial dose: 10-15 mg once daily as monotherapy 1
- When combined with lithium or valproate, start at 10 mg once daily 1
- Dosage range: 5-20 mg/day 1
Acute Agitation (Intramuscular)
- Recommended dose: 10 mg intramuscular 1
- Lower doses of 5 mg or 7.5 mg may be considered when clinical factors warrant 1
- Subsequent doses up to 10 mg may be given if agitation persists 1
- Maximum: 30 mg total daily dose, with injections spaced at least 2-4 hours apart 1
Special Population Adjustments
Elderly Patients
- Consider lower starting doses (5 mg/injection for intramuscular, 5 mg/day for oral) 1
- The American Geriatrics Society recommends using lower starting doses for elderly patients 2, 3
- Dose reduction to 5 mg may be considered in elderly or oversedated patients 4
Hepatic Impairment
- Lower starting doses should be considered 2
- The American Association for the Study of Liver Diseases recommends reduced initial dosing 3
Debilitated or Pharmacodynamically Sensitive Patients
- Consider 2.5 mg/injection for intramuscular administration 1
- Consider 5 mg/day for oral administration 1
Adolescent Dosing (Ages 13-17)
Schizophrenia
- Titration schedule: 3
- Days 1-2: 2 mg/day
- Days 3-4: 5 mg/day
- Day 5 and beyond: 10 mg/day
- Target dose: 10 mg/day 1
- Range: 2.5-20 mg/day 1
Bipolar I Disorder (Acute Mania)
- Initial dose: 2.5-5 mg once daily 1
- Target dose: 10 mg/day 1
- Doses above 20 mg/day have not been evaluated 1
Pediatric Dosing (Ages 6-17)
Autism Spectrum Disorder
- Dose range: 5-15 mg/day 3
- Fixed doses of 5,10, or 15 mg/day have been studied with response rates of 56% at 5 mg versus 35% on placebo 3
Combination Therapy
With Fluoxetine (Bipolar Depression)
- Start with 5 mg olanzapine + 20 mg fluoxetine once daily in the evening 1
- Dosage range: olanzapine 5-12.5 mg with fluoxetine 20-50 mg 1
- Efficacy demonstrated with olanzapine 6-12 mg and fluoxetine 25-50 mg 1
- Safety above 18 mg olanzapine with 75 mg fluoxetine has not been evaluated 1
Pharmacokinetic Considerations
- Mean elimination half-life: approximately 75 hours (range 21-54 hours) 2, 5
- Plasma clearance is approximately 26 L/h (range 12-47 L/h) 5
- Smokers and men have higher clearance than women and nonsmokers 5
- Fluvoxamine (CYP1A2 inhibitor) increases olanzapine concentrations; carbamazepine and smoking decrease concentrations 5
Critical Safety Considerations
- Maximal intramuscular dosing (3 doses of 10 mg at 2-4 hour intervals) may cause significant orthostatic hypotension 1
- Assess for orthostatic hypotension before administering subsequent intramuscular doses 1
- Do not combine intramuscular olanzapine with diazepam (causes precipitation) or lorazepam (delays reconstitution) 1
- Most common adverse effects include weight gain, somnolence, dizziness, dry mouth, and constipation 6, 7