ALS is a progressive motor neuron disease with no effective treatment. The anti-excitotoxic drug riluzole (100 mg/day) has been shown to decrease mortality and muscular deterioration in ALS patients. To confirm and extend the therapeutic effect of riluzole, we performed a double-blind, placebo-controlled, multicenter, international, dose-ranging (50, 100, 200 mg/day), stratified study in 959 ALS outpatients treated for up to 18 months. Primary efficacy criterion was survival and the effect of treatment was analyzed before (Wilcoxon and log rank tests) and after adjustment on prognostic factors (Cox model). Secondary efficacy criterion was disease progression assessed through change in functional measures. Tracheostomy-free survival rates were: 50.4% (placebo), 55.3% (50 mg riluzole) (p = 0.23, Wilcoxon test; p = 0.25, log-rank test), 56.8% (100 mg riluzole) (p = 0.05, Wilcoxon test; p = 0.076, log-rank test), and 57.8% (200 mg riluzole) (p = 0.061, Wilcoxon test; p = 0.075, log-rank test). At the end of the 18-month study, there was a significant dose-related decrease in risk of death or tracheostomy (p = 0.04). Adjustment for baseline prognostic factors showed a 35% decreased risk of death with the 100-mg dose compared with placebo (p = 0.002). No significant treatment effects were detected for the functional assessments. The most frequent dose-related adverse events included nausea, asthenia, and elevated liver enzyme levels. This study confirms the therapeutic effect of riluzole in a large representative ALS sample, over an 18-month period. Riluzole is well tolerated and decreases the risk of death or tracheostomy in ALS patients.

Treatment with the neuroprotective drug riluzole has previously been shown to increase the probability of survival in patients with amyotrophic lateral sclerosis. This report describes a placebo-controlled, double-blind randomised clinical trial of riluzole carried out in ALS patients with advanced stage disease or aged over 75 years. The primary objective was to enable access to treatment to patients excluded from the pivotal trial which was run in parallel. Another goal was to assess the safety of riluzole in patients with advanced-stage disease. One hundred and sixty-eight patients were included, randomised to either riluzole 50 mg b. i. d. or to placebo, and treated for eighteen months. Riluzole was well-tolerated in this patient population, and the adverse events observed were similar in nature and frequency to those observed in previously published clinical trials in patients included in pivotal trials. The study could not include enough patients to reach adequate power to detect differences in survival between the two treatment groups, and no such difference was in fact observed. In conclusion, riluzole is well-tolerated in ALS patients with advanced stage disease.

The pharmacokinetics of riluzole has been characterized in patients during long-term therapy. Riluzole clearance is independent of dose and treatment duration. Within-patient variability is low. Gender and smoking status are the main covariates to explain interpatient variability.

1Intracellular calcium levels were measured in cultured cerebellar granule cells of the rat by use of the fluorescent dye, indo-l/AM. 2 Intracellular calcium levels were increased by depolarizing stimuli such as N-methyl-D-aspartate (NMDA) (100 SAM), glutamic acid (20 LM), and veratridine (10 tiM). This increase was essentially due to entry of external calcium.3 Riluzole (10 pM) blocked responses to all the depolarizing agents. 4 Riluzole could still block the increase in intracellular calcium evoked by NMDA or glutamic acid when sodium channels were blocked by tetrodotoxin, suggesting that this effect is not mediated by a direct action of riluzole on the voltage-dependent sodium channel. 5Pretreatment of the cells with pertussis toxin (0.1 jg ml-1) did not modify the increases in intracellular calcium evoked by NMDA, glutamic acid or veratridine. 6 In pertussis toxin-treated cells, riluzole could no longer block responses to excitatory amino acids, but still blocked responses to veratridine. 7 It is concluded that riluzole has a dual action on cerebellar granule cells, both blocking voltagedependent sodium channels and interfering with NMDA receptor-mediated responses via a pertussis toxin-sensitive mechanism. Furthermore, these two processes have been shown to be independent.

High-affinity specific receptors of endothelin (ET-1) were identified on primary cultures of mouse embryo striatal astrocytes by binding experiments performed with 125I-ET-1. Stimulation of production of inositol phosphates, a biphasic increase of the intracellular calcium concentration, and inhibition of cyclic AMP accumulation were observed in the same cells under ET-1 stimulation. Pretreatment of these cells with Bordetella pertussis toxin affected these effects to different extends, an observation suggesting that they are mediated by multiple transduction pathways, possibly involving several guanine nucleotide-binding proteins.