What is the recommended tapering regimen to switch an inpatient from olanzapine 15 mg to quetiapine?

Tapering Regimen for Switching from Olanzapine 15 mg to Quetiapine

When switching from olanzapine 15 mg to quetiapine in an inpatient setting, a gradual cross-titration over 1-2 weeks is recommended to minimize discontinuation effects and maintain symptom control. 1

Cross-Titration Protocol

Week 1:

• Days 1-3:
  • Olanzapine 10 mg daily
  • Start quetiapine 100 mg twice daily (200 mg total)
• Days 4-7:
  • Olanzapine 5 mg daily
  • Increase quetiapine to 200 mg twice daily (400 mg total)

Week 2:

• Days 8-10:
  • Olanzapine 2.5 mg daily
  • Quetiapine 300 mg twice daily (600 mg total)
• Days 11-14:
  • Discontinue olanzapine
  • Quetiapine 300-400 mg twice daily (600-800 mg total)

Rationale for Cross-Titration

A gradual cross-titration approach is essential when switching between antipsychotics to:

1. Prevent withdrawal symptoms from olanzapine
2. Avoid rebound psychosis or symptom exacerbation
3. Minimize receptor-binding competition between medications
4. Allow for dose adjustment based on patient response

The inpatient setting provides an ideal environment for this switch, allowing for close monitoring of therapeutic response and potential side effects during the transition period 1.

Monitoring Parameters

During the cross-titration period, monitor for:

• Efficacy: Changes in psychotic symptoms, agitation, or sleep disturbances
• Side effects:
  • Sedation/drowsiness (common with both medications)
  • Orthostatic hypotension (particularly with quetiapine)
  • Extrapyramidal symptoms
  • QTc prolongation (ECG monitoring recommended)
• Vital signs: Blood pressure, heart rate, temperature
• Mental status: Emergence of delirium or worsening psychosis

Important Considerations

• Receptor profiles: Olanzapine has stronger dopamine D2, histamine H1, and muscarinic receptor binding compared to quetiapine, which may lead to different side effect profiles during transition 1.

• Sedation management: Both medications can cause sedation, with quetiapine often being more sedating initially. Consider administering the larger portion of the quetiapine dose at bedtime to manage sedation 1.

• Avoid abrupt discontinuation: Abrupt discontinuation of olanzapine can lead to withdrawal symptoms including nausea, vomiting, insomnia, and rebound psychosis 1.

• Dosing equivalence: The final quetiapine dose (600-800 mg) approximates the therapeutic equivalence of 15 mg olanzapine for most patients, though individual response varies.

Pitfalls to Avoid

1. Excessive sedation: If the patient experiences excessive sedation during cross-titration, consider slowing the titration rate or adjusting the timing of doses.

2. Anticholinergic withdrawal: Olanzapine has stronger anticholinergic effects than quetiapine. Watch for emergence of cholinergic rebound symptoms (nausea, vomiting, diarrhea, sweating) during tapering.

3. Inadequate dosing: Quetiapine typically requires higher mg doses than olanzapine to achieve similar efficacy. Underdosing quetiapine is a common pitfall.

4. Excessive dopamine blockade: Avoid combining olanzapine with other medications that cause dopamine blockade (like metoclopramide or haloperidol) during the transition to prevent extrapyramidal symptoms 1.

5. Metabolic monitoring: Both medications can cause metabolic side effects, though olanzapine typically has a higher risk. Continue monitoring metabolic parameters during and after the switch.

The inpatient setting provides an ideal environment for this medication transition, allowing for close observation and immediate intervention if needed.