Viagra may help lessen heart defects from muscular dystrophy

Viagra, developed to help ailing hearts long before it got a more high-profile job fighting erectile dysfunction, might help treat heart symptoms of muscular dystrophy, researchers reported on Monday.

The team, working with funds from the National Institute of Health (NIH) in the US and non-profit groups, tested Viagra in mice that had heart damage similar to that seen in muscular dystrophy.

Joseph Beavoa of the University of Washington and colleagues at the University of North Carolina found that the drug could improve how the heart works in genetically engineered mice, having a condition similar to Duchenne muscular dystrophy.

It is still not clear how the drug helped the mice, but they said it might be worth trying as a treatment for muscular dystrophy.

Duchenne muscular dystrophy affects an estimated one in 3,500 males, according to the NIH.

"Duchenne muscular dystrophy (DMD) is a progressive and fatal genetic disorder of muscle degeneration. Patients with DMD lack expression of the protein dystrophin as a result of mutations in the X-linked dystrophin gene," the researchers wrote.

Because of the involvement of the X chromosome, boys (having only one copy of the X chromosome) are far more likely to be affected than girls, who have two copies of the X chromosome and, thus, are likely to have a 'spare' copy of the healthy gene.

Muscles all over the body, including in the heart, break down as the patient grows up. Many patients die of heart failure and most patients with the condition die before the age of 40.

Viagra, known generically as sildenafil, is sold by Pfizer for erectile dysfunction and under the brand name Revatio to treat a heart condition called pulmonary hypertension.

It is included in a class of drugs called PDE5 inhibitors that work in a variety of ways to increase blood flow.

"Although PDE5 inhibitors will certainly not cure DMD, the current studies suggested that they could be used in combination with current or future therapies," the researchers wrote.

The findings were reported in the journal Proceedings of the National Academy of Sciences.