Muscular dystrophy: $1M grant for study of erectile dysfunction drugs in improving muscle blood flow

A Cedars-Sinai Heart Institute cardiologist has been awarded a three-year, nearly $1 million grant from the Muscular Dystrophy Association (MDA) to study whether drugs used to treat erectile dysfunction could also be used to improve muscle blood flow and reduce fatigue in muscular dystrophy patients.

The study, led by Ronald G. Victor, M.D., associate director of the Cedars-Sinai Heart Institute, co-directed by Gail Thomas, Ph.D. and funded by the Muscular Dystrophy Association (MDA), is intended to build on recent findings published in the journal Nature showing beneficial effects of tadalafil (also known as Cialis) in mice with an animal version of Duchenne and Becker muscular dystrophy. Only two doses of tadalafil improved muscle blood flow, allowing the dystrophic mice to perform more exercise with less muscle injury.

Victor's new short-term clinical trial will move the testing from animals to human patients with Becker muscular dystrophy and examine the effects of acute tadalafil dosing on muscle blood flow during a bout of exercise. Patients will take two doses of tadalafil prior to exercising. Then doctors will measure whether muscles receive increased blood flow and therefore are better protected during exercise.

Duchenne muscular dystrophy is an inherited wasting disease characterized by weakness and progressive degeneration of the muscles -- including the heart muscle - and is caused by a genetic mutation of dystrophin, a protein vital to healthy muscles. Muscle degeneration usually begins in the legs and pelvis, but later affects the whole body. By age 10, most patients experience heart problems. By their early-teenage years, most people with Duchenne muscular dystrophy are in a wheelchair. Becker muscular dystrophy is a milder form of muscular dystrophy that typically is diagnosed in early-adulthood.

"This is an exciting next step in the research I have been doing for 25 years, because we don't need to create a new drug -- the drug already exists," Victor said. "We now have the opportunity to find out if tadalafil can offer some hope for improving the lives of patients and allow them to do more exercise with less muscle injury."

Victor's study is open to adult males 18 - 55 who have Becker muscular dystrophy as well as adult males who don't have it. The study includes includes hand grip exercise testing, measurements of muscle blood flow and oxygen delivery, and magnetic resonance imaging of the muscles.

Source: Cedars-Sinai Medical Center