Thanks Steve. That's pretty much what my new Neurologist said. I'm on a very low dose this week, just to make sure my body tolerates it, but I've already noticed small changes. Getting in and out of the car is easier and I recover a little quicker after walking. So I am hopeful.

I take it

Silvia, Glad to help and glad to hear that there is a medication that can make a difference for you. One day you may take a medication that resolves all the symptoms of Myotonic Dystrophy!!

Silvia,
Just did an AI search with Gemini and got this information on mexiletine. Hope this is helpful.
Mexiletine is a medication originally developed as a heart rhythm regulator (antiarrhythmic) that has become a key treatment for managing specific symptoms of Myotonic Dystrophy (DM) and other myotonic disorders.
While it does not treat the underlying muscle wasting of muscular dystrophy, it is highly effective for a specific symptom called myotonia.
1. Primary Use: Managing Myotonia
Myotonia is the inability of muscles to relax quickly after a contraction (e.g., struggling to let go after a handshake). Mexiletine works by blocking sodium channels in the muscle membrane, which helps "calm" the over-excited electrical signals that cause this stiffness.
* Myotonic Dystrophy Type 1 (DM1): Research shows Mexiletine can significantly reduce handgrip relaxation time and overall muscle stiffness.
* Myotonic Dystrophy Type 2 (DM2): It is also used to treat similar stiffness and muscle pain in DM2 patients.
* Non-Dystrophic Myotonias (NDM): It is considered a first-line therapy for these rarer, non-progressive conditions.
2. Clinical Evidence & FDA Status
* Off-Label Use: In the United States, Mexiletine is FDA-approved for life-threatening ventricular arrhythmias, but it is frequently prescribed off-label by neurologists for myotonia.
* Orphan Drug Designation: The FDA has granted Mexiletine "Orphan Drug" status for myotonic disorders to encourage further research and formal approval for this specific use.
* Effectiveness: Clinical trials (such as those from the University of Rochester) have shown that patients often experience a 40-50% improvement in muscle stiffness and a reduction in associated muscle pain.
3. Key Considerations & Side Effects
Because Mexiletine affects sodium channels in both the muscles and the heart, it requires careful medical supervision.
| Category | Common Side Effects | Precautions |
|---|---|---|
| Gastrointestinal | Nausea, heartburn, indigestion. | Usually taken with food to minimize upset. |
| Neurological | Dizziness, lightheadedness, tremors. | Often dose-related; may improve with adjustment. |
| Cardiac | Palpitations or changes in heart rhythm. | Crucial: Patients often need an EKG before starting to ensure there are no underlying heart block issues. |
Important Note
Mexiletine is typically not used for other forms of muscular dystrophy, such as Duchenne or Becker, where myotonia is not a primary symptom. It is specifically targeted at the electrical "stiffness" seen in the myotonic varieties