A small study from the Cedars-Sinai Heart Institute in Los Angeles has found that the erectile dysfunction drugs Viagra and Cialis could improve blood flow in young men and boys with Duchenne Muscular Dystrophy. The disease, which normally affects boys and young men, is a muscle-wasting disorder characterized by blood flow problems. Blood vessels do not enlarge normally during activity, which prohibits blood flow from increasing, essentially starving the muscles of oxygen.

Nitric oxide is the chemical that signals the blood vessels to relax and expand during exercise, allowing increased blood flow. Duchenne muscular dystrophy (DMD) causes the body to produce little or no dystrophin, the protein needed to make nitric oxide. The genetic disease causes a progressive loss of muscle function, finally progressing to the point that it reaches the muscles needed to breathe and pump blood through the body, resulting in death, usually before age 30. Many people with DMD are confined to a wheelchair as early as age 10.

The study, published online yesterday in the journal Neurology, looked at 10 boys, aged 8-13, who had blood flow problems related to DMD. All of the boys in the study could walk, but some also used a wheelchair. Lead researcher Dr. Ronald Victor says blood flow in the boys’ muscles immediately improved to a healthy level after receiving either Viagra or Cialis.

Victor says he hopes that the disease progression might be slowed by improving blood flow, but noted that it would not cure it. He also said that the typical effects of the erectile dysfunction medication might cause some embarrassing side effects, but hopes a larger study will find a correct dosage that will address this.

Professor Steve Winder from the University of Sheffield said the study showed indications of a “small beneficial effect,” but that there is no evidence that the treatment stops the muscle atrophy. He says the study also does not address whether the treatment would improve a person’s ability to walk, which would be the best measure of effectiveness. Muscular Dystrophy Campaign director of research Dr. Marita Pohlschmidt said the study was encouraging, but that now it must be established whether the improvement in blood flow caused by the Viagra and Cialis treatment would slow the muscle-wasting progression of the disease, and whether the use of the erectile dysfunction drugs to treat DMD is safe.

DMD affects one in 3,500 male babies. Typical treatments to date have been cardiac-protective blood pressure medications and steroids that are prescribed at early ages in an attempt to delay the worst effects of the disease for a few years. But these treatments do not affect the blood flow issues that cause the muscle wasting, and they do not work in 25 percent of cases.

The results of the small study, which used Viagra and Cialis to improve blood flow in boys with DMD, have led to development of a larger clinical trial which is enrolling people now in the U.S. and abroad. The new study will follow boys with DMD aged 7-14 to see if 48 weeks of treatment with a daily dose of Cialis will slow the decline in walking ability.