First treatment for non-dystrophic myotonia approved in EU


  • Dawn O'Shea
  • Univadis Medical News
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The European Medicines Agency (EMA) has recommended granting marketing authorisation for Namuscla (mexiletine hydrochloride) for the treatment of myotonia in adult patients with non-dystrophic myotonia (NDM). 

The EMA opinion will now be referred to the European Commission (EC) for approval. The EC decision is expected within three months and will apply to all 28 EU countries as well as Norway, Iceland and Liechtenstein. If approved, Namuscla will be the first treatment licensed throughout the EU for the treatment of symptomatic myotonia in adults with non-dystrophic myotonic (NDM) disorders. The therapy had already been awarded orphan drug designation in 2014.

The safety of the sodium channel blocker mexiletine has been established as it has been authorised as an antiarrhythmic in Europe since the 1970s. The EMA opinion on the new indication for myotonia was based on findings from the pivotal phase 3 MYOMEX study which involved 25 participants who were diagnosed with NDM and symptomatic myotonia. The treatment was shown to reduce muscle stiffness and improve quality of life. The most common side effects were abdominal pain, vertigo and insomnia. Mexiletine has been associated with arrhythmias and DRESS (drug reaction with eosinophilia and systemic symptoms).