One year safety and efficacy of inosine to increase the serum urate level for patients with Parkinson's disease in Japan.

BACKGROUND: Epidemiological studies have repeatedly reported that increased serum urate level is associated with a slower progress of Parkinson's disease (PD). The urate precursor, inosine, raises the serum urate level and is therefore a candidate for a disease modifying treatment. However, an elevated serum urate level is a risk factor for gout, urolithiasis, and cardiovascular diseases. Although there have been previous clinical studies, the use of inosine in a clinical setting is still limited, and its safety is unclear, especially in an Asian population.

METHODS: We conducted a single-arm, single-center clinical trial to assess the safety of inosine for PD patients with relatively low urate levels. After informed consent, 10 subjects were orally administered inosine to maintain a target urate level between 6.0mg/dl and 8.0mg/dl for one year. All adverse effects were recorded and categorized by severity. Also, the efficacy of using inosine to raise the serum urate level was reported.

RESULTS: We did not observe any adverse events requiring termination or reduction of the study drug, although uric acid crystalluria was transiently observed in a single subject. An inosine dosage of 1070 (SD=501) mg/day significantly raises the urate level from 3.5 (0.84)mg/dl at baseline to 6.68 (1.11)mg/dl at the 52nd week.

CONCLUSIONS: Inosine was safely used for one year and effectively raised urate levels in a small group of subjects. Our study is the first report to use inosine for patients with PD in an Asian population.