Muscular dystrophy is a catch-all name for a group of inherited muscle-wasting diseases. Over time, face, arm, leg, spine and heart muscles weaken and wither.

Viagra (sildenafil citrate) is known to inhibit the breakdown of cyclic GMP, an enzyme that not only dilates the blood vessels in the penis, but is also involved in the signalling pathways that keep the heart healthy.

A group of researchers led by Christine Des Rosiers at the Montreal Heart Institute, Canada, administered an adrenaline-like substance in mice that had been engineered to develop features of human MD.

Des Rosiers found that mice given a dose of Viagra equivalent to the amount a man would receive for erectile dysfunction coped significantly better than animals not given the drug. Echocardiography and other measures showed that the heart function was better, suggesting that Viagra had protected the heart muscle, the New Scientist online said in a report on Tuesday.

"It makes perfect sense that it would work in these mouse models," says Elizabeth McNally, at the University of Chicago Medical Center, Illinois. "It fits."