Effectiveness of Mexiletine for Treating People With Non-Dystrophic Myotonia

• Status: Completed
• Trial end date: 2011-03-01
• Target enrollment: 0
• Participant gender: All

Summary

Nondystrophic myotonias (NDM) are neuromuscular disorders caused by genetic abnormalities in certain muscle cell membrane proteins. The proteins affect muscle contraction. Individuals with NDM experience limited muscle relaxation, which then can cause pain, weakness, incoordination, and impaired physical activity and function. Because NDM is very rare, information on the best way to treat people with the disorders is lacking, and there are no FDA-approved therapies. The purpose of this study is to determine the effectiveness of the medication mexiletine in treating people with NDM.

• Phase: Phase 2
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: Richard Barohn, MD
• Treatments: Mexiletine

Criteria

Inclusion Criteria:

• Clinical symptoms or signs suggestive of myotonic disorders

• Presence of myotonic potentials on electromyography (EMG)

• Participant in the Non-Dystrophic Natural History study (RDCRN 5303) or a new patient with confirmed non-dystrophic myotonia

Exclusion Criteria:

• Other neurological condition that might affect the assessment of the study measurements

• Genetic confirmation of DM1 (more than 50 repeats of CTG) or DM2

• Existing cardiac conduction defects, as evidenced on EKG, including but not limited to the following conditions: malignant arrhythmia or cardiac conduction disturbances (e.g., second degree AV block, third degree AV block, or prolonged QT interval)

• Existing permanent pacemaker

• Current use of any of the following antiarrhythmic medications for a cardiac disorder:

flecainide acetate, encainide, disopyramide, procainamide, quinidine, propafenone, or mexiletine

• Use of medications for myotonia, such as phenytoin and flecainide acetate, within 5 days of study entry; carbamazepine and mexiletine within 3 days of study entry; or propafenone, procainamide, disopyramide, quinidine, and encainide within 2 days of study entry

• Use of medications that produce myotonia, which may include fibrate acid derivatives, hydroxymethylglutaryl CoA reductase inhibitors, chloroquine, and colchicines

• Kidney or liver disease

• Heart failure

• Seizure disorder

• Pregnant or breastfeeding