Can Rytary and Buspar Be Taken Together in Parkinson's Disease?
Yes, Rytary (carbidopa/levodopa extended-release) and Buspar (buspirone) can be taken together, but buspirone has limited efficacy for anxiety in Parkinson's disease and may worsen motor symptoms in some patients, particularly at higher doses.
Evidence for Concurrent Use
Safety Profile at Anxiolytic Doses
- Buspirone at standard anxiolytic doses (less than 40 mg/day) does not adversely affect parkinsonian disability, based on an open-label study in 11 patients with Parkinson's disease where seven patients completed 10 weeks at 50-70 mg/day without significant clinical changes. 1
Tolerability Concerns at Higher Doses
- In a randomized trial of buspirone for anxiety in Parkinson's disease, 41% of participants failed to complete the study on drug, with 5 of 7 discontinuations due to intolerability. 2
- 53% of buspirone-treated participants experienced adverse events consistent with worsened motor function, though no serious adverse events occurred. 2
- The median tolerated buspirone dose was only 7.5 mg twice daily (15 mg/day total), well below the typical anxiolytic target of 20-30 mg/day. 2
- Two of the three most severely affected patients had mild worsening of parkinsonian symptoms when buspirone doses were increased to 65-100 mg/day. 1
Rytary Background
Pharmacokinetics and Efficacy
- Rytary contains carbidopa/levodopa beads designed to release at different rates, providing constant therapeutic levodopa concentrations maintained for 4-5 hours (after an initial peak at approximately 1 hour). 3
- Rytary significantly reduced daily "off-time" in patients with advanced Parkinson's disease compared to immediate-release carbidopa/levodopa, without increasing troublesome dyskinesia. 3, 4
- Extended-release formulations provide symptom relief for 4-6 hours in responsive patients, compared to 2-3 hours with immediate-release formulations. 5
Clinical Recommendations
When to Consider This Combination
- Use buspirone only if anxiety is clinically significant and other treatments have failed, given the limited efficacy and motor tolerability concerns. 2
- Start buspirone at 7.5 mg twice daily (the median tolerated dose in Parkinson's patients) rather than the standard 5 mg twice daily starting dose used in non-Parkinson's populations. 2
- Avoid buspirone doses above 40 mg/day in Parkinson's patients, as higher doses are associated with worsening motor symptoms. 1
Monitoring Parameters
- Assess motor function at each visit using objective measures (e.g., Movement Disorder Society-Unified Parkinson's Disease Rating Scale) to detect any worsening of tremor, rigidity, or bradykinesia. 5
- Monitor specifically for worsened motor function within the first 4-6 weeks of buspirone initiation, as this was the most common adverse effect in clinical trials. 2
- Evaluate anxiety response using standardized scales (e.g., Hamilton Anxiety Rating Scale or Parkinson Anxiety Scale) after 8-12 weeks of treatment. 2
Alternative Anxiety Treatments
- Consider SSRIs or SNRIs as first-line pharmacotherapy for anxiety in Parkinson's disease, as these have better evidence for efficacy and tolerability than buspirone. 2
- 88% of participants in the buspirone trial were already on concomitant antidepressants or anxiolytics, suggesting that buspirone is typically used as adjunctive therapy rather than monotherapy. 2
Critical Pitfalls to Avoid
- Do not titrate buspirone aggressively in Parkinson's patients—the median tolerated dose (15 mg/day) is far below the typical anxiolytic target of 30-60 mg/day. 2
- Do not assume buspirone will be well-tolerated simply because it is safe in non-Parkinson's populations—motor worsening occurred in over half of treated patients. 2
- Do not continue buspirone if motor symptoms worsen—discontinue and consider alternative anxiolytics with better evidence in Parkinson's disease. 2, 1