Blood pressure drug may help with muscular dystrophy

WASHINGTON -- A widely used blood-pressure drug reduced muscle damage in mice with the most common form of muscular dystrophy, researchers report.

A team at Johns Hopkins University found the drug losartan seemed to improve muscle regeneration in mice with a rare condition known as Marfan syndrome and in mice with Duchenne muscular dystrophy -- the most common form in children.

"The results are very intriguing and certainly worthy of further investigation," said Dr. Valerie Cwik, medical director of the Muscular Dystrophy Association.

While noting that it is only a single study, Cwik said the drug is currently used in children and has a good safety profile.

The only current treatment for Duchenne has side effects, so it is worth investigating whether this can offer an alternative, said Cwik, who was not part of the research team.

In Marfan mice treated with the drug, the aorta was strengthened, reducing the chance of an aneurysm in which this major blood vessel bursts.

"In addition to the aortic defect, children with severe Marfan syndrome often have very small, weak muscles, and adults with Marfan often can't gain muscle mass despite adequate nutrition and exercise," Dr. Harry C. Dietz of Johns Hopkins, the lead researcher, said in a statement.

Researchers wondered whether the muscle response was specific to Marfan or if they had discovered something basic about muscle biology. So they then tested the drug in mice with Duchenne muscular dystrophy.

After six months of treatment, the mice showed a significant reduction in muscle damage.

The mice showed increased grip strength in their fore- and hind-limbs and experienced less fatigue in repetitive tests, the researchers reported in today's online issue of the journal Nature Medicine.

Losartan was approved for use as a blood pressure medication in 1995 by the Food and Drug Administration. It is known to block a protein known as TGF-beta.

Excessive activity by TGF-beta is associated with reduced muscle generation and repair, leading Dietz's team to test it against Marfan and then muscular dystrophy.

Duchenne muscular dystrophy is a muscle-wasting genetic disorder that affects only boys. It occurs in about 1 in every 3,500 male births. It is the most severe and most common childhood form of muscular dystrophy and the best-known.

Marfan is a genetic disorder that affects about 1 in 5,000 to 10,000 individuals.

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On the Net:

Nature Medicine: http://www.nature.com/naturemedicine

Muscular Dystrophy Association: http://www.mda.org/