VIAGRA® for Muscular Dystrophy

Muscular dystrophy (MD) is the name for a group of conditions that causes a weakness and eventual degeneration of the skeletal muscles. There are several different forms. The most common is Duchenne MD, accounting for 50 percent of all cases.

Patients with Duchenne MD lack a protein, called dystrophin, used to support muscle cell structure and strength. Without dystrophin, the cell membrane is too permeable, allowing other body components to leak into the cell. Eventually, the pressure from the extra contents causes the cell to rupture and die, causing the muscle fibers to degenerate.

According to the National Institute of Neurological Disorders and Stroke, Duchenne MD occurs in about one out of every 3,500 births. It’s caused by a mutation on the X chromosome, and thus, is mostly seen in boys (because they have only one X chromosome, while girls have two). However, girls can carry the defective gene and pass the disease onto their male children.

Signs of Duchenne MD typically first appear between 2 and 6. Children may have frequent falls, clumsiness, trouble getting up after sitting or lying down and a waddle-like gait. Muscle degeneration and weakness starts in the upper legs and pelvis and spreads to the arms. Eventually, the condition affects posture, breathing (caused by weakness of the respiratory muscles) and heart function. Many boys with Duchenne MD require a wheelchair by the time they reach 10 to 12 years. Researchers estimate children have a median life expectancy of about 30, with most patients dying from respiratory complications, infection or heart failure.

VIAGRA® for Duchenne MD

Kathryn Wagner, M.D., Ph.D., Neurologist with the Kennedy Krieger Institute in Baltimore, MD, says there are some medications that can be given to ease symptoms of MD. Patients may also benefit from physical therapy, occupational therapy, surgery and assisted ventilation. However, currently there are no treatments to stop or reverse the muscle degeneration.

Researchers are now testing the oral drug, VIAGRA® (sildenafil citrate) for children with Duchenne MD. Although the drug is currently marketed for erectile dysfunction, it was originally developed as a heart medication. Investigators are thus hopeful VIAGRA will be beneficial for boys and young men whose hearts have been weakened by Duchenne MD.

The study will last for one year. For the first six months, participants are randomly assigned to take VIAGRA or a placebo three times a day. Then, for the second six months, everyone in the study will take VIAGRA. MRI scans will be done throughout the study to follow the effects of the treatments on a patient’s heart function.

A recent study in mice bred to develop Duchenne MD showed VIAGRA reduced functional heart deficits AND rapidly reversed symptoms of heart failure (within a few days of treatment). The researchers involved in the human study are hopeful VIAGRA will work as well in people. Wagner says there is some data that suggests VIAGRA may also improve skeletal muscle function.

The study is still recruiting participants. For information, click here, then type the trial identification number in the search box: NCT01168908.

For general information about Duchenne muscular dystrophy or other types of MD:

Muscular Dystrophy AssociationNational Institute of Neurological Disorders and Stroke