Effectiveness of mexiletine treatment for myotonic dystrophy type 1

Start Date
01/06/2011
Expected end Date
01/10/2014
Location
USA
Status
Recruiting

What is the aim of the trial?

Myotonic dystrophy type 1 is caused by a specific genetic change (mutation) that usually involves a gene on chromosome 19. This mutation disrupts the pores (‘channels’) in the cell walls of muscle cells. These channels usually transport ions such as sodium into and out of the cells which causes the muscles to contract and relax. One of the most noticeable effects is the inability of patients to relax their muscles after contracting them, for example after gripping (‘myotonia’).

This phase 2 clinical trial tests if patients with myotonic dystrophy type 1 can be treated with mexiletine. Mexiletine is already in use to treat patients with irregular heartbeats, who also have defective ion channels. It is thought that mexiletine binds to the ion channels and restores their function.

There have been two previous clinical trials that tested mexiletine as a treatment for myotonic dystrophy type 1 (see link below). These short seven-week trials tested two different doses of mexiletine (450 mg per day or 600 mg per day) in twenty patients. Mexiletine was well tolerated at both doses and helped patients relax their muscles more quickly after gripping.

This trial will be longer (six months) and test twice as many patients. The main aim is to determine if mexiletine improves walking. Another aim is to test the safety of mexiletine treatment over a longer treatment period, and its effects on muscle strength, heart function and quality of life.

Who can be involved in the trial?

This study will recruit 40 patients aged between 18 to 80 years who have a genetically confirmed diagnosis of myotonic dystrophy type 1. Participants must be able to walk for 6 minutes, which may be aided by a walking stick or leg braces.

Patients may be excluded from participation if they:
• had severe myotonic dystrophy at birth (‘congenital’ myotonic dystrophy).
• have certain liver, kidney or heart problems
• have certain other medical conditions such as another neuromuscular disease, a seizure disorder, multiple sclerosis, diabetes or cancer
• have had problems with alcohol, drugs or depression within the last three months
• received mexiletine in the previous eight weeks
• are pregnant or breast-feeding

Refer to the link under “Further trial details” for a more detailed list.

What happens during the trial?

Participants will be randomly assigned to a treatment group (receives mexiletine) or a control group (receives an inactive substance known as a ‘placebo’). Patients and medical staff will not know who receives the placebo or the mexiletine. This prevents bias in noticing improvements in the mexiletine group. Mexiletine or placebo tablets will be taken three times a day for six months at a dose of 150 milligrams (total daily dose of 450 mg).

Participants will have three appointments at the University of Rochester (months 0, 3 and 6) and will be tested for their:
• performance in a six minute walk test
• muscle mass, function and strength
• heart and digestive function
• ability to release grip (myotonia)
• quality of life and pain

The safety of mexiletine will be monitored by laboratory tests, heart scans (echocardiograms), physical exams and a portable heart monitor.

In addition, patients will be interviewed by phone every two weeks and complete a daily journal.

Where is the study taking place?

The University of Rochester Medical Center, Department of Neurology, Rochester, New York, United States, 14642.

In most circumstances, for somebody to participate in a clinical trial, they need to live near the team of people who are conducting the research, because they need to be closely monitored.

How could the results of the trial benefit patients?

If successful, this phase 2 trial could be followed by a larger phase 3 trial. If mexiletine is found to be a safe and effective drug in patients with myotonic dystrophy type 1, it could become a new treatment option. As mexiletine is already a registered drug in the UK, this could happen relatively soon after the trial.

Contact Details:

Liz Luebbe

Health Project Coordinator

Tel: +1 585 275 7867

Email: elizabeth_luebbe@urmc.rochester.edu

Who is funding this study?

  • The Federal Drug Administration Office for Orphan Products Development.

Official name of the Trial:

A randomized, placebo controlled, clinical efficacy trial of mexiletine for myotonic dystrophy type-1 (DM1)

Trial study number:

NCT01406873

Further trial details:

For further information on the trial and detailed inclusion and exclusion please click on the link below. Sometimes these details can be quite technical. If you have any questions please discuss this with your clinician or contact the clinical trial organisers.

www.clinicaltrials.gov/show/NCT01406873

Background information and related links:

Myotonic dystrophy type 1 is caused by a specific genetic change (mutation) that usually involves a gene on chromosome 19. This mutation disrupts the pores (‘channels’) in the cell walls of muscle cells. These channels usually transport ions such as sodium into and out of the cells which causes the muscles to contract and relax. One of the most noticeable effects is the inability of patients to relax their muscles after contracting them, for example after gripping (‘myotonia’).

This phase 2 clinical trial tests if patients with myotonic dystrophy type 1 can be treated with mexiletine. Mexiletine is already in use to treat patients with irregular heartbeats, who also have defective ion channels. It is thought that mexiletine binds to the ion channels and restores their function.

There have been two previous clinical trials that tested mexiletine as a treatment for myotonic dystrophy type 1 (see link below). These short seven-week trials tested two different doses of mexiletine (450 mg per day or 600 mg per day) in twenty patients. Mexiletine was well tolerated at both doses and helped patients relax their muscles more quickly after gripping.

This trial will be longer (six months) and test twice as many patients. The main aim is to determine if mexiletine improves walking. Another aim is to test the safety of mexiletine treatment over a longer treatment period, and its effects on muscle strength, heart function and quality of life.

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