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ALS Worldwide
March 15, 2016

Mexiletine for Muscle Cramps

“As if all the other symptoms associated with ALS aren’t bad enough, add painful muscle cramps to the equation. For me, it was annoying but for some of us, it is extremely painful. In the past, my husband Bill would have to rub my legs to make the cramps stop. However, thanks to a recommendation from ALS Worldwide about 4 years ago, I started taking Mexiletine. It works! No more muscle cramps (don’t tell Bill though because then he won’t massage my legs anymore!) It's a capsule, so it is relatively easy to take three times a day.”

Debbie Gattoni

Muscle cramps affect 92 percent of people with ALS/MND, according to a survey conducted by Dr. Björn Oskarsson, who directs the ALS clinic at UC Davis. He found that they are often the only source of pain for people with ALS/MND.

A study recently published in Neurology online suggests that people may find significant relief from muscle cramp frequency and severity by taking 300 mg per day of Mexiletine, a drug currently on the market that was originally developed to treat heart arrhythmia.

Dr. Michael Weiss of the University of Washington School of Medicine, and Principal Investigator on the Mexiletine trial, states, “The Phase 2 trial clearly shows that Mexiletine is safe to use in ALS patients and reasonably well tolerated, which is what we had hoped when we initiated the study. The dramatic effects on muscle cramps are much more than what we expected and suggest that Mexiletine could become a treatment of choice for this often substantial and debilitating complication of ALS."

In 2003, researchers reported Mexiletine alleviated cramping in Machado-Joseph disease, a form of spinocerebellar ataxia. That inspired Drs. Oskarsson, Weiss and a small group of other physicians to prescribe it ‘off-label’ for ALS. “It works like a charm,” Oskarsson said.

ALS Worldwide has always been at the forefront of ‘off-label’ drug use, advocating for cross-prescription to best treat the symptoms of ALS/MND patients as long as it is based on firm scientific rationale, sound evidence, and professional medical judgment. Over the past three years, ALS Worldwide has highly recommended that people discuss the use of Mexiletine with their prescribing physicians. We’re pleased that this recent study confirms what we have seen firsthand.

However, no randomized controlled trials supported the practice until now. Dr. Weiss’ study, which included an array of collaborators, including senior author Dr. Merit Cudkowicz of Massachusetts General Hospital in Boston, recruited 60 volunteers with ALS to 10 different study sites in the Northeast ALS Consortium. Dr. Oskarsson is currently conducting a 30-person Phase 4 trial in people with severe cramps. Dr. Weiss and his colleagues plan to conduct additional clinical trials of Mexiletine in the near future.

If you or your physician have any questions or would like to discuss our viewpoints regarding this medication, please email us at [email protected].