Viagra may help heart in muscular dystrophy: study (Reuters)

WASHINGTON (Reuters) - A Canadian study involving miceshows that anti-impotence pills might protect the hearts ofpeople with a common form of muscular dystrophy, researcherssaid on Monday.

Canadian researchers gave sildenafil, the active ingredientin drug maker Pfizer Inc's Viagra, to mice with an animalversion of Duchenne muscular dystrophy, and found that itimproved their heart performance.

They said it would be premature to give Viagra to peoplewith the disease, but said the results indicate the drugpotentially could be used to prevent or delay heart failure inchildren with Duchenne muscular dystrophy.

The mice were given doses of the drug comparable to thoseadministered to treat erectile dysfunction in men. The study,published in the Proceedings of the National Academy ofSciences, showed that sildenafil cut the levels of damage tocontracting heart muscle cells.

"If you don't give the sildenafil, the heart of these micedoesn't function as well as normal mice, and they are moresusceptible to stress-induced cell death," said researcherChristine Des Rosiers of the Montreal Heart Institute.

She said in an interview the drug worked to improve heartperformance in the mice by preventing the breakdown of anaturally occurring chemical. Called cyclic guanosinemonophosphate, or cGMP, it is involved in a number of cellularsignaling pathways, the researchers said.

Other impotence drugs also affect the chemical cGMP,including vardenafil, sold by Schering Plough under the brandname Levitra, and tadalafil, sold by Eli Lilly and Co. underthe brand name Cialis.

Duchenne muscular dystrophy is an inherited wasting diseasecharacterized by weakness and progressive degeneration of themuscles, including the heart muscle. It begins in the legs andpelvis, and later affects the whole body. Most people with thedisease must use a wheelchair by about age 12.

It is caused by a genetic mutation of dystrophin, a proteinvital to muscle cells.

Heart problems can appear at around age 10 and theyprogress quickly, affecting most people with the disease by age20. These heart problems are an important cause of death amongpatients with muscular dystrophy.

Sildenafil was developed as a heart drug and is widelyprescribed for erectile dysfunction as well as pulmonaryhypertension. The researchers said discussions are under wayabout possible future studies using the drug in patients withmuscular dystrophy.

"There's a lot of information on this drug that shows itappears to be relatively safe in adults," Des Rosiers said,while emphasizing that future human clinical trials are neededbefore doctors prescribe it for heart trouble in thesepatients. (Editing by Maggie Fox and Doina Chiacu)