The last 20 years Parkinson’s disease researchers have sought to identify a compound that could potentially slow disease progression. One candidate has been inosine, a drug that elevates blood uric acid levels. Uric acid elevation has been associated with a lower risk of Parkinson’s disease, but also with a higher risk of the development of kidney stones and gout.
Inosine is thought to work as an anti-oxidant, an anti-inflammatory, and potentially as an immunomodulatory molecule in the brains of Parkinson’s disease patients, however the exact mechanism(s) of action remains unknown. Inosine raises blood uric acid levels. Investigators became interested in this compound when it was discovered that higher uric acid was associated with a decreased risk of development of Parkinson’s disease.
The Parkinson Study Group designed a study “to determine the safety, tolerability, and urate-elevating capability of the urate precursor inosine in early PD and to assess its suitability and potential design features for a disease-modification trial.” The study was also named the Safety of Urate Elevation in PD (SURE-PD) study. The design was a randomized double-blind placebo-controlled dose-ranging design to mainly examine safety and tolerability. The study was conducted in 17 sites, and included 75 men and women with early PD who had not yet begun treatment with a dopaminergic medication. The blood urate level had to be normal (less than 6 mg/dL). Study participants received either placebo pills, pills to mildly elevate blood urate levels, or pills to moderately elevate blood urate levels. Serious adverse events were similar in the inosine versus placebo groups. Three people in the inosine group developed kidney stones, and none developed gout. Inosine was considered well tolerated. The study was able to show that inosine could raise blood and cerebrospinal fluid (brain) concentrations of urate. The study also revealed that it was reasonable to continue to a second study to determine if inosine will affect disease progression.
Should you take inosine to raise your uric acid level if you have Parkinson’s disease? We do not recommend that you use inosine for your Parkinson’s disease. Most of the available data examined the risk of development of Parkinson’s disease, and not actually people with a diagnosis of Parkinson’s disease. Additionally, many potentially disease modifying compounds for Parkinson’s disease have been shown to be ineffective, and the current data only revealed that inosine was reasonably safe, and that it gets to the brain. Finally, inosine has not to date been shown to have a meaningful symptomatic benefit. Though the results of the current study are promising, we are still a ways away from declaring inosine as an effective neuroprotective agent for early stage Parkinson’s disease patients.
The Parkinson Study Group SURE-PD Investigators, Schwarzschild MA, Ascherio A, Beal MF, Cudkowicz ME, Curhan GC, Hare JM, Hooper DC, Kieburtz KD, Macklin EA, Oakes D, Rudolph A, Shoulson I, Tennis MK, Espay AJ, Gartner M, Hung A, Bwala G, Lenehan R, Encarnacion E, Ainslie M, Castillo R, Togasaki D, Barles G, Friedman JH, Niles L, Carter JH, Murray M, Goetz CG, Jaglin J, Ahmed A, Russell DS, Cotto C, Goudreau JL, Russell D, Parashos SA, Ede P, Saint-Hilaire MH, Thomas CA, James R, Stacy MA, Johnson J, Gauger L, Antonelle de Marcaida J, Thurlow S, Isaacson SH, Carvajal L, Rao J, Cook M, Hope-Porche C, McClurg L, Grasso DL, Logan R, Orme C, Ross T, Brocht AF, Constantinescu R, Sharma S, Venuto C, Weber J, Eaton K. Inosine to Increase Serum and Cerebrospinal Fluid Urate in Parkinson Disease: A Randomized Clinical Trial. JAMA Neurol. 2013 Dec 23. doi: 10.1001/jamaneurol.2013.5528. [Epub ahead of print] PubMed PMID: 24366103.
You can find out more about our National Medical Director, Dr. Michael S. Okun, by also visiting the Center of Excellence, University of Florida Health Center for Movement Disorders and Neurorestoration. Dr. Okun is also the author of the Amazon #1 Parkinson's Best Seller 10 Secrets to a Happier Life and 10 Breakthrough Therapies for Parkinson's Disease.