Phase 2
Completed N=59
Effectiveness of Mexiletine for Treating People With Non-Dystrophic Myotonia
Myotonia · Non-Dystrophic Myotonia
Source: ClinicalTrials.gov NCT00832000 ↗
Enrolled (actual)
59
Serious AEs
0.9%
Results posted
Mar 2013
Primary outcomePrimary: Patient-reported Stiffness on the IVR — 2.53; 4.21; 1.60; 5.27 units on a scale — p=<0.001
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.
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Patient-reported Stiffness on the IVR |
2.53; 4.21; 1.60; 5.27 | <0.001 sig |
| SECONDARY Patient Reported Pain on the IVR |
1.54; 3.17 | <0.001 sig |
| SECONDARY Patient Reported Weakness on the IVR |
1.96; 3.22 | <0.001 sig |
| SECONDARY Patient Reported Tiredness on the IVR |
2.90; 3.82 | <0.001 sig |
| SECONDARY Quantitative Measure of Hand Grip Myotonia (Seconds) |
0.321; 0.429 | <0.001 sig |
| SECONDARY Compound Motor Action Potentials After Short Exercise Test |
83.1; 78.6 | 0.09 |
| SECONDARY Graded Myotonia by Needle Electromyography - Right Abductor Digiti Minimi |
2.05; 2.62 | <0.001 sig |
| SECONDARY Clinical Hand Grip Myotonia Evaluation (Seconds) |
0.164; 0.494 | <0.001 sig |
| SECONDARY Clinical Eye Closure Myotonia Evaluation (Seconds) |
0.161; 0.474 | <0.001 sig |
| SECONDARY Graded Myotonia by Needle Electromyography - Right Tibialis Anterior |
2.07; 2.54 | <0.001 sig |
| SECONDARY Compound Motor Action Potentials After Long Exercise Test |
81.8; 80.1 | 0.50 |
| SECONDARY Individualized Neuromuscular Quality of Life Scale - Summary Score |
14.0; 16.7 | <0.001 sig |
| SECONDARY Short Form 36 - Physical Composite Score |
44.8; 39.2 | <0.001 sig |
| SECONDARY Short Form 36 - Mental Composite Score |
47.4; 47.7; 53.1; 42.7 | 0.90 |
Eligibility 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
Data sourced from ClinicalTrials.gov (NCT00832000). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication. Informational only — not medical advice.