Long-term safety of riluzole in amyotrophic lateral sclerosis.
This international, open-label, multicentre extension of riluzole pivotal studies was designed to assess the long-term safety of riluzole in the treatment of amyotrophic lateral sclerosis (ALS). The studies were carried out at 31 different centres, 23 in Europe and eight in North America. 516 patients with diagnosed probable or definite ALS and who had participated previously in one of two international multicentre randomized double-blind placebo-controlled, parallel-group trials, were enrolled in the extensions. 58 of these patients had taken part in a randomized phase II trial (placebo or riluzole 100 mg/day) and 458 in a randomized, dose-ranging phase III trial (placebo or riluzole, 50, 100 or 200 mg/day). All participants in the open-label continuation received 100 mg/day of riluzole (50 mg b.i.d.) At the end of the open-label study, the average exposure time of the patients to riluzole was 28.7 +/- 14.4 months, with a maximum exposure time of 81 months. Most of the adverse events recorded reflected the progression of ALS, in particular the deterioration of the respiratory status of the patients. No particular adverse event, or frequency of adverse event, appeared to be related to the dose level of the previous double-blind riluzole treatment. Nor were any adverse events associated with the switch-over from double-blind placebo to open-label riluzole. This open-label extension study reinforces and extends the results of the preceding double-blind trials regarding the safety of riluzole and shows that the drug is well tolerated for long periods of up to almost 7 years.