Conversion from Risperidone 2 mg to Lurasidone or Aripiprazole
Direct Recommendation
For switching from risperidone 2 mg to lurasidone, initiate lurasidone at 40 mg/day while tapering risperidone to 50% by day 7 and discontinuing it completely by the end of week 2. 1 For switching to aripiprazole, start aripiprazole at 7.5-15 mg/day (equivalent to risperidone 2 mg) using either immediate discontinuation or a 2-week cross-taper strategy. 2, 3
Conversion to Lurasidone
Starting Dose and Titration Strategy
Begin lurasidone at 40 mg/day for the first 2 weeks, which has been demonstrated effective in a randomized switching study of 240 patients with schizophrenia or schizoaffective disorder. 1
Alternative strategies include starting at 80 mg/day immediately or up-titrating from 40 mg to 80 mg on day 8, though the 40 mg starting dose minimizes adverse effects during transition. 1
After the initial 2-week stabilization period, lurasidone can be flexibly dosed between 40-120 mg/day based on clinical response. 1
Risperidone Discontinuation Protocol
Taper the risperidone to 50% of the original dose (1 mg) by day 7, then discontinue completely by the end of week 2. 1
This gradual cross-titration allows time for receptor adaptation, as risperidone is a full D2 antagonist while lurasidone also acts as a full D2 antagonist, making the transition pharmacologically smoother than switches involving partial agonists. 2
Monitoring Considerations
Monitor for dose-related adverse effects including somnolence, akathisia (12.5% incidence), nausea, and parkinsonism/extrapyramidal symptoms. 2, 1
The treatment failure rate during switching is low (7.9%), with most failures occurring in patients switched from sedating antipsychotics like olanzapine or quetiapine. 1
Expect improvements in metabolic parameters: lurasidone demonstrates no clinically relevant adverse changes in weight, glucose, insulin, lipids, or prolactin, with mean improvements in weight and lipids observed. 1
Conversion to Aripiprazole
Dose Equivalency
Risperidone 2 mg is approximately equivalent to aripiprazole 7.5 mg/day based on chlorpromazine equivalent dosing (risperidone 2 mg = 100 mg chlorpromazine = aripiprazole 7.5 mg). 4
The American Psychiatric Association recommends a gradual taper of the prior antipsychotic over 2 weeks while initiating aripiprazole to minimize treatment failure and allow receptor adaptation, as aripiprazole is a partial D2 agonist while risperidone is a full D2 antagonist. 2
Three Validated Switching Strategies
Strategy 1 (Immediate Switch): Start aripiprazole 30 mg/day with immediate discontinuation of risperidone. 3
Strategy 2 (2-Week Cross-Taper): Start aripiprazole 30 mg/day immediately while tapering risperidone over 2 weeks. 3
Strategy 3 (Gradual Up-Titration): Up-titrate aripiprazole to 30 mg/day over 2 weeks while simultaneously tapering risperidone. 3
All three strategies demonstrated comparable efficacy, safety, and tolerability in a multicenter randomized study, with no deterioration in extrapyramidal symptoms across any group. 3
A Japanese study comparing immediate versus delayed tapering (add-on aripiprazole, wait 4 weeks, then taper) found both strategies equally safe and well-tolerated, suggesting either approach is reasonable based on patient preference. 5
Practical Implementation for Risperidone 2 mg
Given the lower dose of risperidone (2 mg), start aripiprazole at 12-15 mg/day rather than 30 mg/day to avoid excessive dopaminergic stimulation during the transition. 5
Titrate aripiprazole between 12-30 mg/day based on response, reducing risperidone biweekly by 25% until discontinued. 5
Expected Outcomes
Patients' symptoms may continue to improve after switching to aripiprazole, with maintained efficacy throughout the transition period. 3
Expect reductions in body weight and plasma prolactin levels following the switch, comparable across all switching strategies. 3
Critical Considerations
Receptor Pharmacology Differences
The switch from risperidone (full D2 antagonist) to aripiprazole (partial D2 agonist) requires careful monitoring, as abrupt discontinuation could lead to withdrawal symptoms or symptom exacerbation due to the pharmacological shift. 2
The risperidone-to-lurasidone switch is pharmacologically simpler as both are full D2 antagonists, reducing the risk of receptor-mediated complications. 2
Renal Impairment Caveat
- For patients with severe renal impairment, the maximum lurasidone dose should not exceed 80 mg/day. 2