Can a patient on haloperidol 10 mg daily be switched to risperidone 2 mg, then start paliperidone palmitate (Invega Sustenna) one week later and discontinue haloperidol on the same day as the first injection?

Switching from Haloperidol to Paliperidone Palmitate via Risperidone Bridge

Yes, you can switch from haloperidol 10 mg daily to risperidone 2 mg, then initiate Invega Sustenna one week later while discontinuing haloperidol on the same day as the first injection, but this approach is suboptimal and carries risk of relapse—a 7-day bridge with oral risperidone after the Invega injection is strongly recommended for patients on higher-dose oral antipsychotics. 1

Critical Dosing Concern: Haloperidol 10mg is High-Dose

• Haloperidol 10 mg daily is a relatively high dose (typical range 0.5-5 mg for most indications) 2
• Risperidone 2 mg is inadequate as a direct equivalent to haloperidol 10 mg—this represents significant underdosing during the transition period 2, 3
• The one-week gap between starting risperidone 2 mg and initiating Invega Sustenna creates a period of subtherapeutic antipsychotic coverage 1

Evidence-Based Bridging Strategy

Patients on risperidone ≥4 mg daily (which would be the appropriate equivalent for haloperidol 10 mg) require oral bridging for ≥7 days after the first paliperidone palmitate injection to prevent relapse. 1

• A study comparing bridged vs. non-bridged patients found statistically significant reductions in hospitalization days in patients who received oral risperidone for ≥7 days after their first paliperidone injection 1
• The paliperidone palmitate package insert does not recommend bridging, but this approach results in inadequate serum concentrations in patients previously on higher oral doses 1

Recommended Switching Protocol

Step 1: Cross-taper appropriately

• Increase risperidone to 4-6 mg daily (not 2 mg) to match the antipsychotic potency of haloperidol 10 mg 2, 4
• Maintain this dose for at least 3-7 days before initiating paliperidone palmitate 1

Step 2: Initiate Invega Sustenna with proper loading

• Day 1: Administer 150 mg equivalent paliperidone (234 mg paliperidone palmitate) deltoid injection 5
• Day 8 (±2 days): Administer 100 mg equivalent paliperidone (156 mg paliperidone palmitate) deltoid injection 5
• Continue oral risperidone 4-6 mg daily for 7-14 days after the first injection 1

Step 3: Discontinue oral antipsychotics

• Taper haloperidol completely before or during the first week of risperidone 5
• Discontinue risperidone 7-14 days after the first paliperidone injection (not on the same day) 1

Why Your Proposed Timeline is Problematic

Antipsychotic gap creates relapse risk:

• Stopping haloperidol on the day of Invega injection leaves the patient with only 1 week of risperidone 2 mg coverage beforehand 1
• Paliperidone palmitate takes time to reach therapeutic levels—the loading dose strategy exists precisely because steady-state is not immediate 5
• Patients switched without adequate bridging show increased hospitalization rates 1

Risperidone 2 mg is insufficient:

• For first-episode psychosis, risperidone 2 mg daily is appropriate, but your patient is on haloperidol 10 mg, suggesting more severe or treatment-resistant illness 2, 3
• The optimal target dose of risperidone is 4 mg/day for most patients with established schizophrenia 3

Alternative Approach if You Must Use This Timeline

If clinical circumstances absolutely require this abbreviated timeline:

• Increase risperidone to 4 mg daily (not 2 mg) during the one-week bridge period 3, 4
• Administer the Invega Sustenna loading doses as scheduled (150 mg day 1,100 mg day 8) 5
• Continue risperidone 4 mg for at least 7 days after the first Invega injection before tapering 1
• Monitor closely for early signs of relapse (increased agitation, sleep disturbance, paranoia) 1

Monitoring Requirements

• Assess for extrapyramidal symptoms at each visit, as both haloperidol and paliperidone can cause EPS 2, 6
• Monitor for akathisia, tremor, and rigidity, particularly during the cross-taper period 2, 3
• Check serum prolactin levels, as paliperidone palmitate causes significantly higher prolactin elevations than haloperidol 6
• Weigh patient at baseline and monthly, as paliperidone causes average weight gain of 2.17 kg over 6 months 6

Common Pitfall to Avoid

Do not stop haloperidol abruptly on the day of Invega injection without adequate oral bridging—this creates a therapeutic gap that significantly increases relapse risk, particularly in patients previously requiring high-dose typical antipsychotics. 1