The Myomex trial, conducted by the AP-HP (the Paris public hospital system) and supported by AFM-Téléthon, evaluated the efficacy and safety versus placebo of a daily dose of 600 mg of mexiletine (Namuscla®) in 25 participants, 13 of which had myotonia congenita and 12 of which had paramyotonia congenita. Their symptoms had to be sufficiently severe to justify treatment.
The results of this trial show a significant improvement versus placebo:
- muscle rigidity score, determined by participants using a visual analogue scale, went from 71 at the start of the trial, to 16 after 18 days of treatment (-78%);
- quality of life in its different dimensions.
A trial of Namuscla® in children and adolescents with non-dystrophic myotonias has begun.