A new research has discovered that a drug commonly used to treat cardiac arrhythmias also lessens a central symptom of myotonic dystrophy, the most common form of muscular dystrophy in grown-ups.

The discoveries on the drug mexiletine - a chemical cousin of lidocaine - were released May 4 in the journal Neurology.

At present, there is no drug permitted to cure myotonic dystrophy, an inherited illness, which is marked by progressive weakness of muscles. While the course of the illness can differ dramatically from patient to patient, warning signs besides weakness can comprise muscle rigidity, difficulty speaking and swallowing, problems walking, and in some patients, heart troubles and eye diseases.

The scientists at the University of Rochester Medical Center discovered that the drug is good at handling the myotonia - muscle stiffness. Turning a key in a lock, using a pen or pencil, picking up and setting down a pitcher of water - all are difficult tasks for myotonia sufferers.

Sometimes the warning sign first happens when a sufferer shakes someone's hand, then cannot relax his or her grip for several seconds.

While many physicians have suspected that the drug helps cure myotonia, this is the first placebo-controlled, trial research to explain that it really does so, said neurologist Richard Moxley III, M. D., an author of the study and an international expert on muscular dystrophy.

Moxley, who is director of the University's Neuromuscular Disease Center and professor of Neurology, said, "It's important for physicians who treat patients to know that mexiletine is an option."

"Several physicians who specialize in treating patients with myotonic dystrophy have found it to be effective for their patients, but we really wanted to study the issue closely. The medication really addresses myotonia quite well, with no additional risk," Moxley added. (With Inputs from Agencies)