Riluzole is a medication used to treat amyotrophic lateral sclerosis and other motor neuron diseases. Riluzole delays the onset of ventilator-dependence or tracheostomy in some people and may increase survival by two to three months. Riluzole is available in tablet and liquid form. Medical use Amyotrophic lateral sclerosis Riluzole was approved in the United States for the treatment of ALS by the U.S. Food and Drug Administration (FDA) in 1995. A Cochrane Library review states a 9% gain in the probability of surviving one year. Adverse effects Very common (>10% frequency): nausea; weakness; decreased lung function Common (1–10% frequency): headache; dizziness; drowsiness; vomiting; abdominal pain; increased aminotransferases Uncommon (0.1-1% frequency): pancreatitis; interstitial lung disease Rare (<0.1% frequency): neutropenia; allergic reaction (including angiooedema, anaphylactoid reaction) Overdose Symptoms of overdose include: neurological and psychiatric symptoms, acute toxic encephalopathy with stupor, coma and methemoglobinemia. Severe methemoglobinemia may be rapidly reversible after treatment with methylene blue. Contraindications Contraindications for riluzole include: known prior hypersensitivity to riluzole or any of the excipients inside the preparations, liver disease, pregnancy or lactation. Interactions CYP1A2 substrates, inhibitors and inducers would probably interact with riluzole, due its dependency on this cytochrome for metabolism. Mechanism of action Riluzole preferentially blocks TTX-sensitive sodium channels, which are associated with damaged neurons. Riluzole has also been reported to directly inhibit the kainate and NMDA receptors. The drug has also been shown to postsynaptically potentiate GABAA receptors via an allosteric binding site. However, the action of riluzole on glutamate receptors has been controversial, as no binding of the drug to any known sites has been shown for them. In addition, as its antiglutamatergic action is still detectable in the presence of sodium channel blockers, it is also uncertain whether or not it acts via this way. Rather, its ability to stimulate glutamate uptake seems to mediate many of its effects. In addition to its role in accelerating glutamate clearance from the synapse, riluzole may also prevent glutamate release from presynaptic terminals. Since CK1δ plays a key role in TDP-43 proteinopathy, a pathological hallmark of ALS, this could help to better decipher drug mechanism of action. Synthesis Riluzole can be prepared beginning with the reaction of 4-(trifluoromethoxy)aniline with potassium thiocyanate followed by reaction with bromine, forming the thiazole ring. Society and culture Legal status Riluzole was approved for medical use in the European Union in October 1996. Research A number of case studies have indicated