Switching from Abilify 10 mg to Zyprexa in an Inpatient Hospital Setting
When switching from Abilify (aripiprazole) 10 mg to Zyprexa (olanzapine), the recommended approach is gradual cross-titration with an initial olanzapine dose of 5 mg daily while tapering aripiprazole over 1-2 weeks to minimize risk of symptom exacerbation and adverse effects. 1
Initial Dosing of Olanzapine
- Start olanzapine at 5 mg once daily (preferably at bedtime) while the patient is still taking aripiprazole 10 mg 1, 2
- For older or medically compromised patients, consider starting at a lower dose of 2.5 mg 2
- Olanzapine can be administered as oral tablet or orally disintegrating tablet (ODT) formulation depending on patient preference and ability to swallow 2
Cross-Titration Schedule
Week 1:
- Days 1-3: Continue aripiprazole 10 mg + Start olanzapine 5 mg daily
- Days 4-7: Reduce aripiprazole to 5 mg + Maintain olanzapine at 5 mg daily
Week 2:
- Days 8-10: Discontinue aripiprazole + Continue olanzapine 5 mg daily
- Days 11-14: Adjust olanzapine dose based on clinical response (typical range 5-10 mg daily)
Monitoring During Switch
- First 24-48 hours: Monitor for sedation, orthostatic hypotension, and extrapyramidal symptoms 1
- First week: Assess for clinical response and emergence of side effects daily
- Second week: Continue monitoring for metabolic effects (weight gain is a particular concern with olanzapine) 2
Rationale for Cross-Titration
Research evidence supports gradual cross-titration rather than abrupt discontinuation when switching antipsychotics. Patients switched with immediate discontinuation of the previous antipsychotic show increased symptom severity at week 1 3. The INTEGRATE guidelines specifically recommend that "antipsychotic switching should involve gradual cross-titration informed by the half-life and receptor profile of each medication" 1.
Important Considerations
- Pharmacodynamic differences: Aripiprazole is a partial D2 agonist while olanzapine is a D2 antagonist with significant 5-HT2A antagonism, requiring careful transition 1
- Sedation risk: Olanzapine is more sedating than aripiprazole, so bedtime dosing is recommended 1, 2
- Metabolic effects: Olanzapine carries higher risk of weight gain and metabolic effects compared to aripiprazole 2
- Drug interactions: Assess for any medications that might affect metabolism of either medication
Cautions
- Avoid combining with benzodiazepines when possible, as this combination increases risk of oversedation and respiratory depression 1, 2
- Monitor vital signs regularly during the switch period, particularly for orthostatic hypotension
- Assess for extrapyramidal symptoms which may occur during the transition period
Special Situations
- For patients with acute agitation: If needed during the switch period, olanzapine can be administered at 5-10 mg for acute agitation 1
- For older patients: Use lower starting doses (2.5 mg) and slower titration 2
- For patients with hepatic impairment: Start with 2.5 mg and titrate more slowly 2
This cross-titration approach minimizes the risk of rebound symptoms, withdrawal effects, and adverse events while maintaining therapeutic coverage during the transition between these two antipsychotics with different pharmacological profiles.