Cross-Tapering from Chlorpromazine 50mg BID to Olanzapine
The recommended cross-taper from chlorpromazine 50mg BID to olanzapine should begin with olanzapine 5mg daily while gradually reducing chlorpromazine over 2-4 weeks to minimize withdrawal symptoms and ensure adequate antipsychotic coverage.
Initial Assessment and Considerations
Before beginning the cross-taper, consider:
- Chlorpromazine 50mg BID (100mg total daily dose) is approximately equivalent to 5mg of olanzapine daily based on conversion ratios 1
- Both medications have different receptor binding profiles, with olanzapine having stronger 5-HT2A antagonism and less pronounced extrapyramidal side effects than chlorpromazine
- Abrupt discontinuation of antipsychotics can lead to withdrawal symptoms including dyskinesias, parkinsonian symptoms, dystonias, and potentially neuroleptic malignant syndrome 2
Cross-Taper Schedule
Week 1:
- Start olanzapine 5mg at bedtime
- Continue chlorpromazine 50mg BID
Week 2:
- Continue olanzapine 5mg at bedtime
- Reduce chlorpromazine to 50mg in morning and 25mg at night
Week 3:
- Continue olanzapine 5mg at bedtime
- Reduce chlorpromazine to 25mg BID
Week 4:
- Increase olanzapine to 10mg at bedtime if clinically indicated
- Reduce chlorpromazine to 25mg once daily
Week 5:
- Discontinue chlorpromazine
- Continue olanzapine at effective dose (typically 5-15mg daily)
Dose Adjustments and Monitoring
- Monitor for efficacy and side effects throughout the cross-taper
- Olanzapine dosing should be titrated based on therapeutic response and tolerability, with most patients requiring 5-15mg daily 3
- If sedation is problematic, administer the entire olanzapine dose at bedtime
- For elderly patients or those sensitive to sedation, consider a lower olanzapine starting dose of 2.5mg 2
Potential Challenges and Management
Anticholinergic Withdrawal
- Chlorpromazine has stronger anticholinergic effects than olanzapine
- Watch for rebound cholinergic symptoms (nausea, vomiting, diarrhea, sweating)
- If significant withdrawal symptoms occur, slow the taper of chlorpromazine
Sedation Management
- Both medications cause sedation, but the profile differs
- Olanzapine often causes more initial sedation that may improve over time
- Schedule the olanzapine dose at bedtime to minimize daytime sedation
Metabolic Monitoring
- Baseline and follow-up monitoring of weight, blood glucose, and lipids is essential with olanzapine
- Consider concurrent metformin to attenuate potential weight gain with olanzapine 2
Special Considerations
- If the patient has significant positive symptoms, ensure adequate antipsychotic coverage throughout the transition
- If the patient experiences extrapyramidal symptoms on chlorpromazine, these may improve during the cross-taper to olanzapine
- For patients with cardiac concerns, monitor for QTc prolongation, particularly during the period when both medications are being administered 4
This gradual cross-taper approach minimizes the risk of rebound psychosis, withdrawal symptoms, and adverse effects while maintaining adequate symptom control throughout the transition period.