Is it acceptable to change the dosing schedule of risperidone (Risperdal) from twice a day (bid) to once at bedtime (HS) in adult or geriatric patients with schizophrenia or bipolar disorder who are experiencing daytime drowsiness?

Changing Risperidone from BID to HS Dosing for Daytime Drowsiness

Yes, it is acceptable and clinically appropriate to consolidate risperidone from twice-daily (BID) to once-daily bedtime (HS) dosing when a patient experiences daytime drowsiness, as this strategy directly addresses the sedation side effect without compromising efficacy. 1, 2, 3

Evidence Supporting Once-Daily Dosing

Efficacy Equivalence

• Once-daily risperidone administration is equally effective as twice-daily dosing for schizophrenia treatment. A randomized trial of 44 schizophrenic patients receiving 4-8 mg risperidone showed 82% response rate with once-daily dosing versus 79% with twice-daily dosing, with no significant differences in efficacy or adverse effects. 2

• The CATIE schizophrenia study (N=341 risperidone patients) demonstrated no significant differences in discontinuation rates, time to discontinuation, or efficacy outcomes between once-daily and twice-daily dosing regimens over 18 months of follow-up. 3

Side Effect Management Strategy

• Guidelines explicitly recommend evening administration of risperidone to manage sedation or drowsiness, particularly in elderly or frail patients. 1

• The once-daily dosing group in the CATIE study showed lower rates of hospitalization for exacerbation and better tolerability profiles compared to twice-daily dosing. 3

• Patients experiencing persistent somnolence may benefit from administering the medication at bedtime, as stated in FDA labeling for related antipsychotics. 4

Practical Implementation Algorithm

Step 1: Assess Current Dosing

• Calculate the total daily dose currently being administered BID 4
• Verify the patient is on a stable dose (not in active titration phase) 5

Step 2: Consolidate to HS Dosing

• Administer the same total daily dose as a single dose at bedtime 1, 2, 3
• No dose adjustment is necessary when changing from BID to HS—simply consolidate the total daily dose 2, 3

Step 3: Monitor Response

• Assess daytime drowsiness improvement within 3-7 days 1
• Monitor for any breakthrough symptoms or loss of efficacy over 2-4 weeks 4
• Watch for extrapyramidal symptoms, particularly at doses >6 mg/day 1

Special Considerations for Elderly Patients

Dosing Cautions

• In elderly patients, use lower doses (typically ≤2 mg/day) and increase slowly to minimize adverse effects. 6

• Elderly patients showed 85% effectiveness with risperidone at mean doses of 1.6 mg/day, with 78% receiving ≤2 mg/day. 6

• Adverse effects in elderly patients were associated with cardiovascular disease, rapid dose increases, and co-treatment with other psychotropic agents. 6

Safety Monitoring

• Monitor for orthostatic hypotension (occurred in 29% of elderly patients) and symptomatic orthostasis (10%) 6
• Assess for extrapyramidal symptoms (11% incidence in elderly) 6
• Use particular caution with cardiovascular disease or concurrent psychotropic medications 6

Common Pitfalls to Avoid

• Do not split the dose or reduce the total daily dose when consolidating to HS—maintain the same total daily dose to preserve efficacy 2, 3

• Avoid rapid titration schedules—if dose adjustments are needed, increase slowly over 6-7 days in increments of 0.5-2 mg/day 5

• Do not assume morning dosing is appropriate—risperidone should be given in the morning only if the patient experiences paradoxical activation or insomnia, which is uncommon 1

• In elderly patients, avoid doses >2 mg/day without compelling justification, as adverse effects increase substantially 6

Alternative Consideration

• If daytime drowsiness persists despite HS dosing, consider dose reduction rather than splitting back to BID, as lower doses may provide adequate efficacy with improved tolerability 3, 6