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Clinical Efficacy Trial of Mexiletine for Myotonic Dystrophy Type 1

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01406873
Recruitment Status : Completed
First Posted : August 1, 2011
Results First Posted : March 29, 2018
Last Update Posted : June 19, 2018
Information provided by (Responsible Party):
Chad Heatwole, University of Rochester

Brief Summary:
The purpose of this study is to investigate the effects of mexiletine treatment for 6 months on ambulation, myotonia, muscle function and strength, pain, gastrointestinal functioning, cardiac conduction, and quality of life in myotonic dystrophy type 1 (DM1).

Condition or disease Intervention/treatment Phase
Myotonic Dystrophy Drug: Mexiletine Drug: Placebo Phase 2

Detailed Description:

This study will provide data on the long term (6 months) safety and efficacy of mexiletine in:

  • improving the distance participants are able to walk in six minutes;
  • reducing myotonia;
  • improving muscle strength;
  • increasing lean muscle mass;
  • decreasing musculoskeletal pain;
  • improving gastrointestinal function and swallowing);
  • improving functional abilities;
  • decreasing cardiac arrhythmias; and
  • improving disease-specific health related quality-of-life.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 42 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Randomized, Placebo Controlled, Clinical Efficacy Trial of Mexiletine for Myotonic Dystrophy Type-1 (DM1)
Study Start Date : June 2011
Actual Primary Completion Date : February 2017
Actual Study Completion Date : March 2017

Arm Intervention/treatment
Active Comparator: Mexiletine
20 subjects will be randomized (assigned) to receive Mexiletine. Mexiletine is available on the market for the treatment of cardiac arrhythmias, but it is not currently approved for the treatment of myotonia or myotonic dystrophy.
Drug: Mexiletine
150 mg/kg Mexiletine capsules taken by mouth, three times daily for 6 months
Other Name: Generic name: mexiletine hydrochloride

Placebo Comparator: Sugar pill
20 subjects will be randomized (assigned) to receive placebo (sugar pill). This control group is necessary to definitely establish the antimyotonic efficacy and safety of mexiletine.
Drug: Placebo
150 mg/kg placebo capsules taken by mouth, three times daily for 6 months

Primary Outcome Measures :
  1. Mean Change From Baseline in Ambulation Using the 6 Minute Walk Distance [ Time Frame: Baseline to 6 months ]
    During this assessment, participants were asked to walk as far as they could back and forth on a fixed 20 meter route for 6 minutes. The total distance walked during the 6 minutes was recorded in meters. Change from baseline was defined as the difference between the average 6 minute walk distance at baseline and the average 6 minute walk distance at 6 months.

Secondary Outcome Measures :
  1. Percentage of Participants That Had a Dose Reduction or a Study Drug Withdrawal or Suspension Over 6 Months [ Time Frame: 6 months ]
    Adverse events were monitored at the three in-person evaluations (Months 0, 3, and 6), at telephone evaluations every 2 weeks, and via patient-completed side effect diaries. The study investigators and safety monitoring committee reviewed adverse events and made decisions regarding drug withdrawals, suspensions, and dose reductions as needed.

  2. Mean Change From Baseline in Quantitative Measure of Hand Grip Myotonia [ Time Frame: Baseline to 6 months ]
    Relaxation time of the long finger flexor muscles of the right hand after a maximum voluntary isometric contraction performed in a standardized fixed position of the right arm elbow/wrist/hand. Relaxation time for this measurement is defined as the time to relax from 90% to 5% of the maximum isometric force of contraction of the hand (the first of 6 serial contractions averaged over two consecutive trials performed 10 minutes apart).

  3. Mean Change From Baseline in Manual Muscle Testing (MMT) Score [ Time Frame: Baseline to 6 months ]
    Manual muscle testing was performed on 26 muscle groups (shoulder abductors, elbow flexors, wrist flexors, wrist extensors, hip flexors, knee extensors, hip extensors, knee flexors, hip abductors, elbow extensors, ankle dorsiflexors, and plantar flexors on the right and left plus neck extensor and neck flexors). The muscles were tested in various positions including sitting, supine, prone, and side lying and each graded on a modification of the Medical Research Council (MRC) scale of 0 to 5 (5 representing normal strength). Average MMT score is derived by averaging the individual MMT scores across the 26 individual muscles.

  4. Mean Change From Baseline in PR, QRS, and QTc Intervals, and Average Minimum Heart Rate (HR) Via Electrocardiogram (ECG) Monitoring [ Time Frame: Baseline to 6 Months ]
    PR, QRS, and QTc intervals as well as average minimum heart rate (HR) were obtained through standard 12 lead electrocardiograms (ECGs). Values were computer generated and verified by the study investigator and study cardiologist.

  5. Mean Change From Baseline in Patient-Reported Disease Burden and Quality of Life [ Time Frame: Baseline to 6 months ]
    • The Myotonic Dystrophy Health Index (MDHI) is a validated disease-specific measure of patient-reported disease burden. The MDHI total score is a weighted average derived from 17 subscales. MDHI total scores range form 0-100 with 0 representing no patient-reported disease burden and 100 representing the most severe patient-reported disease burden.
    • The Individualized Neuromuscular Quality of Life Questionnaire (INQoL) is a measure of quality of life in neuromuscular disease. The INQoL summary score is a weighted average made up of 5 sub-domains. Scores range from 0-100, and can be interpreted as the percent of maximal detrimental impact on quality of life with higher scores indicating more detrimental impact.
    • The 36-Item Short Form Survey (SF-36) is a generic measure of quality of life across 8 domains. Two summary metrics are produced from the 8 domains, ranging from 0-100% with lower scores representing worse levels of functioning.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   18 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • A diagnosis of DM1, confirmed by DM1 genetic mutation
  • Ability to walk 30 feet (assistance with cane and/or leg bracing permitted)
  • Presence of grip myotonia

Exclusion Criteria:

  • Congenital DM1
  • Treatment with Mexiletine within past 8 weeks
  • Second or third degree heart block, atrial flutter, atrial fibrillation, ventricular arrhythmias, or is receiving medication for treatment of a cardiac arrhythmia
  • Receiving another antimyotonia drug
  • Liver or kidney disease requiring ongoing treatment
  • Has a seizure disorder
  • Is pregnant or lactating
  • Had severe depression within 3 months or a history of suicide ideation
  • Has any one of the following medical conditions: uncontrolled diabetes mellitus, congestive heart failure, symptomatic cardiomyopathy, symptomatic coronary artery disease, cancer (other than skin cancer) less than five years previously, multiple sclerosis, or other serious medical illness.
  • Drug or alcohol abuse within 3 months
  • Coexistence of another neuromuscular disease
  • Is unable to give informed consent
  • Severe arthritis or other medical condition (besides DM1) that would significantly impact ambulation

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01406873

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United States, New York
University of Rochester Medical Center, Department of Neurology
Rochester, New York, United States, 14642
Sponsors and Collaborators
University of Rochester
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Principal Investigator: Richard T. Moxley, III, MD University of Rochester
  Study Documents (Full-Text)

Documents provided by Chad Heatwole, University of Rochester:
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Responsible Party: Chad Heatwole, Associate Professor of Neurology, University of Rochester Identifier: NCT01406873    
Other Study ID Numbers: 3716
Funding Source: FDA/OOPD ( Other Grant/Funding Number: R01FD003716 )
First Posted: August 1, 2011    Key Record Dates
Results First Posted: March 29, 2018
Last Update Posted: June 19, 2018
Last Verified: May 2018
Keywords provided by Chad Heatwole, University of Rochester:
Myotonic Dystrophy
Myotonic Dystrophy Type 1 (DM1)
Muscular Dystrophy
Additional relevant MeSH terms:
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Myotonic Dystrophy
Muscular Dystrophies
Muscular Disorders, Atrophic
Muscular Diseases
Musculoskeletal Diseases
Myotonic Disorders
Heredodegenerative Disorders, Nervous System
Neurodegenerative Diseases
Nervous System Diseases
Neuromuscular Diseases
Genetic Diseases, Inborn
Anti-Arrhythmia Agents
Voltage-Gated Sodium Channel Blockers
Sodium Channel Blockers
Membrane Transport Modulators
Molecular Mechanisms of Pharmacological Action