Clinical Trial: Mexiletine and Non Dystrophic Myotonias

Study Status: Completed
Recruit Status: Completed
Study Type: Interventional

Official Title: Efficacy and Safety of Mexiletine in Non-dystrophic Myotonias

Brief Summary:

Treatment strategies in non-dystrophic myotonias are based on selective case reports, clinical experience and theoretical benefit. Presently, the most promising antimyotonic medication is mexiletine (MEX) but its manufacturing was stopped. The proposed randomized, double-blind, placebo-controlled, crossover trial is designed to:

1. study the safety and efficacy of mexiletine for the treatment of non-dystrophic myotonias
2. validate electromyographic tests as a standardized outcome measure of myotonia
3. assess the reliability and validity of a new clinical rating scale for myotonia

Detailed Summary:

A. Specific aims

Treatment strategies in non-dystrophic myotonias are based on selective case reports, clinical experience and theoretical benefit. Presently, the most promising antimyotonic medication is mexiletine (MEX) but its manufacturing was stopped. The proposed randomized, double-blind, placebo-controlled, crossover with wash-out trial is designed to:

• study the safety and efficacy of mexiletine for the treatment of non-dystrophic myotonias
• validate electromyographic tests as a standardized outcome measure of myotonia
• assess the reliability and validity of a new clinical rating scale for myotonia

B. Research design Because of their differing phenotypes, 12 Paramyotonia Congenita and 12 Myotonia Congenita subjects will be enrolled in a stratified trial

C. Outcome variables

1. primary outcome variable: the score of stiffness severity on a self-assessment scale (100 mm VAS) measured at baseline, at the end of phase I and phase II.

2. secondary outcome measures:

   • of efficacy:

     • standardized EMG measures after repetitive short exercise test at cold and long exercise test
     • chair test: time needed to stand up from a chair, walk around it and sit down again
     • severity and disability scale of my
       Sponsor: Assistance Publique - Hôpitaux de Paris
       

       Current Primary Outcome: score of stiffness severity on a self-assessment scale (100 mm VAS) [ Time Frame: 18 days ]
       
       

       Original Primary Outcome: Same as current
       
       

       Current Secondary Outcome:

       • standardized EMG measures after repetitive short exercise test at cold and long exercise test [ Time Frame: 18 days ]
       • chair test: time needed to stand up from a chair, walk around it and sit down again [ Time Frame: 18 days ]
       • severity and disability scale of myotonia to be validated [ Time Frame: 18 days ]
       • quality of life scale (INQOL) [ Time Frame: 18 days ]
       • CGI efficacy (Clinical Global Impression- Efficacy index) [ Time Frame: 18 days ]
       
       
       

       Original Secondary Outcome: Same as current
       
       Information By: Assistance Publique - Hôpitaux de Paris
       

       Dates:
       Date Received: January 8, 2015
       Date Started: June 2011
       Date Completion:
       Last Updated: January 12, 2015
       Last Verified: January 2015