The FDA approved Mitsubishi Tanabe Pharma's edaravone for amyotrophic lateral sclerosis (ALS), the first US approval for the deadly neurodegenerative disease since riluzole in 1995.

ALS is a rare disease that attacks and kills the nerve cells that control voluntary muscles, affecting the ability to chew, walk, breath and talk. Most people with ALS die from respiratory failure, usually within 3–5 years from when the symptoms first appear. The FDA approved riluzole, a glutamate antagonist, more than two decades ago after clinical trials showed that it delayed the time to death by 3–4 months.

Japanese regulators granted supplemental approval to edaravone for ALS in 2015; they first approved it there in 2001 for acute ischaemic stroke. Although edaravone's mechanism of action in ALS is unknown, it is a radical scavenger with antioxidant effects that might provide neuroprotection against oxidative stress in motor neurons.

In a pivotal trial in 137 ALS patients, edaravone treatment slowed decline in a 48-point clinical test of daily function that assessed fine motor, gross motor, bulbar and respiratory functions of patients. After 24 weeks of treatment, the scores of edaravone-treated patients fell around 2.5 points less from baseline than those of placebo-treated patients. Common side effects included bruising and gait disturbance. It remains unclear what effect, if any, the drug has on survival times.

A few other ALS candidates are in mid- or late-stage trials, including AB Science's phase III multikinase inhibitor masitinib, which is already under regulatory review for approval in ALS in Europe, and Cytokinetics' phase III trial of the fast skeletal muscle troponin activator tirasemtiv.