A trial of buspirone for anxiety in Parkinson's disease: Safety and tolerability.

Introduction: In Parkinson's disease (PD), anxiety is common, associated with lower health-related quality of life, and undertreated. The primary objective of this study was to determine the tolerability of buspirone for the treatment of anxiety in PD.

Methods: Individuals with PD and clinically significant anxiety were randomized 4:1 to flexible dosage buspirone or placebo for 12 weeks. Treatment was initiated at 7.5 mg twice daily and titrated based on response and tolerability to an optimal dosage (maximum 30 mg twice daily). The primary outcome was the proportion of participants who failed to complete the study on study drug. Secondary outcomes included adverse events, dosage reductions, motor function, dyskinesias, and anxiety.

Results: A total of 21 participants enrolled, 4 were randomized to placebo and 17 to buspirone (mean (SD) age 65.5 (9.8), 76.5% male, 88% on concomitant antidepressant or anxiolytic). In the buspirone group, 7 (41%) failed to complete the study on drug, 5 due to intolerability. The median buspirone dosage was 7.5 mg twice daily. No serious adverse events occurred. A total of 9 (53%) buspirone participants experienced adverse events consistent with worsened motor function. In the buspirone group, mean (SD) improvement from baseline to week 12 in Hamilton Anxiety Rating Scale was -3.9 (3.8) and Parkinson Anxiety Scale -7.1 (6.4).

Conclusion: Tolerability concerns do not support moving immediately forward with a large-scale efficacy trial. However, concomitant anxiolytics may have affected tolerability and a signal of efficacy was seen suggesting that future studies of buspirone monotherapy be considered.