October 3, 2012
Stiffness Caused By Certain Muscle Diseases Could Be Reduced With Heart Medicine
Preliminary research finds that for patients with nondystrophic myotonias (NDMs), rare diseases that affect the skeletal muscle and cause functionally limiting stiffness and pain, use of the anti-arrhythmic medication mexiletine resulted in improvement in patient-reported stiffness, according to a preliminary study in the October 3 issue of JAMA.
Data on treatment of NDMs are largely anecdotal, consisting of case series and a single-blind, controlled trials of several medications including mexiletine, according to background information in the article.
Data from 57 participants who made telephone calls to the IVR diary in weeks 3 to 4 of period 1 or 2 were included in the analysis. The researchers found that mexiletine was associated with significantly improved stiffness as reported on the IVR diary in both treatment periods. For period 1, the treatment effect was 2.53 for mexiletine vs. 4.21 for placebo; for period 2, 1.60 for mexiletine vs. 5.27 for placebo.
There were significant improvements with mexiletine in most other outcomes in the study, including patient-reported outcomes, quality of life scales, and quantitative measures of myotonia (improved myotonia as measured on clinical examination by overall handgrip times in seconds).
"The most common adverse effect was gastrointestinal (9 mexiletine and 1 placebo). Two participants experienced transient cardiac effects that did not require stopping the study (1 in each group). One serious adverse event was determined to be not study related," the authors write.
"Our study provides preliminary evidence of the effectiveness of mexiletine for symptoms and signs of myotonia in NDMs," the researchers write. "The clinical significance of the improvement in stiffness score on the IVR diary is supported by the broad improvement in clinical, quantitative, and electrophysiological measures of myotonia."
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