How to switch from quetiapine (Seroquel) to haloperidol (Haldol)?

Switching from Quetiapine to Haloperidol

When switching from quetiapine to haloperidol, implement a gradual cross-titration approach, starting with a low dose of haloperidol (0.5-1 mg/day) while slowly tapering quetiapine over several weeks to minimize withdrawal effects and prevent relapse. 1, 2

Initial Assessment and Preparation

• Verify the clinical indication for switching, as haloperidol is recommended for control of psychotic symptoms including delusions, hallucinations, severe psychomotor agitation, and combativeness 1
• Consider that haloperidol is a first-generation antipsychotic with higher risk of extrapyramidal symptoms (EPS) compared to quetiapine (second-generation antipsychotic) 1, 3
• Ensure baseline laboratory tests are completed, including ECG monitoring if intravenous administration is planned 1
• Inform the patient and family about potential side effects of haloperidol, including EPS, which occur in significantly higher rates compared to quetiapine (59.6% vs 12.7%) 4, 3

Cross-Titration Protocol

• Begin with a low dose of haloperidol (0.5-1 mg orally or subcutaneously) while maintaining the current quetiapine dose 1
• For elderly or frail patients, start with an even lower haloperidol dose (0.25-0.5 mg) 1
• After 2-3 days of co-administration with stable response, begin reducing quetiapine by approximately 25% of the original dose every 5-7 days 2
• Simultaneously, increase haloperidol gradually as needed, typically to 2-3 mg/day for most patients 1
• Monitor closely for emergence of EPS during the transition period, as this is the most common adverse effect with haloperidol 1, 3

Dosing Considerations

• The typical therapeutic dose range for haloperidol is 0.5-5 mg/day for most patients, though doses may vary by indication 1
• Quetiapine is typically dosed at 400-800 mg/day for most conditions, so the equivalent haloperidol dose will be much lower due to different potency 4
• If the patient was on high-dose quetiapine (>600 mg/day), extend the cross-titration period to at least 3-4 weeks to minimize withdrawal effects 2
• Consider scheduling haloperidol doses q8h-q12h if scheduled dosing is required after the transition 1

Monitoring During Transition

• Assess for emergence of extrapyramidal symptoms daily during the switch period using a standardized scale 1, 3
• Monitor for QTc prolongation, particularly if the patient has cardiac risk factors, as both medications can affect cardiac conduction 1
• Watch for signs of withdrawal from quetiapine, including insomnia, anxiety, agitation, and potential rebound psychosis 2
• Evaluate for signs of relapse of the underlying condition, which may occur during the transition period 2

Managing Side Effects

• If EPS occur during the transition, consider:
  • Reducing the haloperidol dose 1
  • Slowing the quetiapine taper 2
  • Short-term use of anticholinergics only if dose reduction strategies are ineffective 1
• Avoid routine prophylactic use of anticholinergics (such as benztropine or trihexyphenidyl) 1
• If sedation is excessive during the transition, consider adjusting the timing of doses (e.g., more haloperidol in the evening) 1

Special Considerations

• For patients with bipolar disorder, consider that both medications are effective for acute mania, but haloperidol may have less efficacy for depressive symptoms 1, 4
• In first-episode schizophrenia patients, be aware that quetiapine may have greater efficacy for negative symptoms compared to haloperidol 3
• For elderly patients or those with dementia, use particularly low doses of haloperidol (0.25-0.5 mg) due to increased sensitivity to side effects 1
• If the patient has Parkinson's disease or Lewy body dementia, haloperidol is contraindicated due to high risk of worsening parkinsonism 1

Follow-up

• Schedule a follow-up appointment within 1-2 weeks after completing the transition to assess efficacy and tolerability 2
• Continue to monitor for tardive dyskinesia, which can develop with long-term haloperidol use (risk of up to 50% in elderly patients after 2 years of continuous use) 1
• Provide psychoeducation to the patient and family about the importance of adherence and potential side effects 1