Rilutek (riluzole) was the first treatment approved by the U.S. Food and Drug Administration (FDA) to treat amyotrophic lateral sclerosis (ALS). Rilutek is an oral formulation that acts to slow the progression of ALS symptoms and prolong survival. Approved in 1995 by the FDA, it was originally developed by the French company Rhone-Poulenc Rorer and is now marketed by Sanofi.

How Rilutek works

Excess levels of the neurotransmitter glutamate are thought to damage nerve cells in many cases of ALS. Neurotransmitters are molecules that nerve cells use to communicate: one nerve cell releases the neurotransmitter, which is then picked up by receptors situated on the surface of a neighboring nerve cell, successfully transmitting the message. Normally, the neurotransmitter is quickly removed from the region surrounding the cell so that the signal is brief. This removal process is critical to normal neural function, because as remaining neurotransmitters continue to send messages to neighboring cells, such prolonged activity is toxic.

The exact mechanism by which Rilutek treats ALS is unknown. However, it is thought that the medicine blocks the release of glutamate from nerve cells. This may reduce the rate of glutamate-induced deterioration in nerve cells, thereby slowing the progression of symptoms.

Rilutek in clinical trials

The FDA’s approval of Rilutek was based on the results of two key clinical trials.

The first trial was a randomized, double-blind clinical study that followed 155 ALS patients in France and Belgium for 13 to 18 months. The patients were randomly assigned to receive either 50 mg of Rilutek or a placebo twice daily. The results showed that Rilutek had a significant effect on the rate of survival. The time until tracheostomy — a medical procedure to create an opening in the neck to allow breathing — or death was about 90 days longer in the Rilutek-treated group compared with the placebo-treated group.

The second trial tested the effect of different doses of Rilutek. A total of 959 ALS patients from Europe and North America were randomly assigned to receive either 50, 100, or 200 mg of Rilutek or a placebo per day for 12 months (North America) or 18 months (Europe). There was no difference observed between the group taking the placebo and the patients given 50 mg a day of Rilutek. However, the researchers saw an early increase in survival rates in patients treated with either 100 or 200 mg a day of Rilutek compared with a placebo. The median survival time was about 60 days longer in the Rilutek-treated group than in the placebo-treated group. There was no change in survival when the dose was increased to 200 mg per day, although there was an increase in the rate of adverse events such as nausea and asthenia (weakness). Based on these results, the recommended dosage of Rilutek is 50 mg twice daily on an empty stomach.

A recent study published in The Lancet Neurology re-examined the patient data from the second trial and found that Rilutek prolongs survival in the last clinical stage of ALS, although more research is needed to confirm this finding. 

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