Riluzole in Huntington's disease (HD): an open label study with one year follow up

In an open label study, we administered riluzole (50 mg twice a day) to nin e patients with genetically confirmed Huntington's disease (HD) (clinical s tages 1-3; mean age 46.4 (SD 9.3) years; mean disease duration 8 (SD 3.3) y ears). The study was designed to evaluate (1) safety and tolerability of ri luzole and (2) effects of riluzole on motor impairment, functional disabili ty, cognitive impairment, and behavioral abnormalities using the Unified HD Rating Scale. Patients were evaluated at baseline and after three and twel ve months of riluzole therapy. Laboratory tests (hematology and liver enzym es) were repeated monthly. All adverse experiences, reported spontaneously or observed directly by the investigator, were recorded. Riluzole was well tolerated. No increase of serum liver enzymes was seen throughout the study in all but one patient showing a mild elevation. At three months, mean tot al motor scale (TMS), mean TMS chorea subscore, and mean total functional c apacity scale were significantly improved compared with baseline. At twelve months, however, this beneficial effect on motor status and overall functi on was not sustained. In contrast, severity and frequency of behavioral dys function as well as psychomotor speed assessed by the symbol digit modaliti es test were improved compared with baseline. Our data suggest that there a re transient antichoreatic effects and more sustained effects of riluzole o n psychomotor speed and behavior in patients with HD. A double-blind, place bo-controlled trial appears highly warranted to establish definitely the sy mptomatic versus neuroprotective actions of riluzole in HD.