Study of Urate Elevation in Parkinson's Disease, Phase 3

A multicenter, randomized, double-blind, placebo-controlled, phase 3 trial to determine whether oral inosine dosed to moderately elevate serum urate (from ≤5.7 mg/dL to 7.1-8.0 mg/dL) over 2 years slows clinical decline in early PD. Clinical decline will be assessed as change in the primary outcome variable of the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), a composite scale comprising patient- and clinician-reported outcomes.

Capsules containing 500 mg of inosine (active drug) or \~500 mg of lactose (placebo) will be taken orally up to two capsules three times per day (i.e., up to 3 g/day) for 24 months. In the inosine-treated group the number of capsules taken per day will be titrated to serum urate levels - measured at trough at study visits no more than three months apart - in order to achieve concentrations of 7.1-8.0 mg/dL. Initial dosing will be tailored to individualized factors including gender and pretreatment serum urate, and then advanced gradually toward the projected target dose. Adjustments in dosing of placebo capsules in the control arm will be algorithm-based to match dosing of inosine capsules in the active drug arm. Following study drug discontinuation all subjects will be followed during a 3-month wash-out period by telephone calls and a final study visit. All study visits after screening will include measurement of the primary outcome variable (MDS-UPDRS) and most will include secondary outcome variables: adverse events, dose adjustments, disability warranting initiation of dopaminergic therapy, Quality of Life in Neurological Disorders (Neuro-QOL), 39-item Parkinson's Disease Questionnaire (PDQ-39), Schwab \& England Activities of Daily Living (S\&E ADL) scale, Montreal Cognitive Assessment (MoCA), and orthostatic vital signs.