No Joke

05.09.14

Viagra Promising for Muscular Dystrophy Patients

Viagra has been the brunt of many jokes, but it might be time to stop laughing. Turns out, the drug may help sufferers of a rare and deadly form of muscular dystrophy.

Viagra and Cialis are two of the most mocked medicines on the market. After all, they cure erectile dysfunction, not cancer. Generally associated with a clientele of horny older men, as evidenced in their commercials featuring silver foxes giving knowing looks to their blushing wives, they’re hardly considered a wonder drug.

But maybe they should be.

The drugs famous ability to restore blood flow to certain parts of the male anatomy has the potential to unlock the cure to some of the hardest-to-treat disorders. In fact, Viagra was originally developed in County Cork, Ireland with the intention of improving blood flow to the heart. The fact that the cardiac patients “kept making tents in the ward,” as the plant’s security officer, Tony Deroe, said, was incidental.

In recent years, the erectile dysfunction medicines have been investigated as treatments for a wide variety of disorders. Sildenafil (the active ingredient in Viagra) and tadalafil (the active ingredient in Cialis) are both phosphodiesterase type 5 inhibitors (PDE5 inhibitor), drugs that cause smooth muscle cells to relax under stress conditions, such as exercise or sexual stimulation. As a result, they can enable blood flow not only to the penis, but the muscles in other regions of the body.

For this reason, sildenafil has already been established as a treatment for pulmonary hypertension, a type of blood pressure affecting the arteries in the lung and the right side of the heart. To combat the effect of narrowed pulmonary arteries and capillaries, sildenafil relaxes the blood vessels in the lungs to reduce blood pressure.

Viagra, along with Cialis and Levitra, was also shown to reduce lower urinary tract symptoms in men who suffered from benign prostate hyperplasia (enlarged prostates). There’s also research suggesting Viagra may help people who suffer from diastolic heart failure by causing cardiac muscle to become more elastic.

After testing the boys’ responses on handgrip exercises before and after doses, Victor concluded that the improvement in blood flow in exercising muscles was “marked, immediate, and dose-dependent.”

Ironically, erectile dysfunction medicines may even benefit the lives of women (other than improving their partners’ sexual abilities). Sildenafil in Viagra has been shown to ease menstrual cramps when administered vaginally by dilating the blood vessels around the uterus. That increases blood flow to flush out excess prostaglandins, which cause abnormal muscle contractions and heightened sensitivity of pain receptors.

And we may soon add one of the most devastating and difficult to treat disorders to the list of ailments alleviated by Viagra and Cialis.  Just this week, a new study from Cedars-Sinai Heart Institute in Los Angeles shows that Viagra and Cialis offer hope for people suffering from Duchenne muscular dystrophy (DMD), an aggressive and deadly form of muscular dystrophy. The degenerative muscle disorder currently has no disease-specific treatment, despite the fact that it is the most common fatal disease affecting children, who are almost entirely male.

Though Viagra and Cialis had been studied as treatments in mouse models and in a milder form of muscular dystrophy, “this is the first human study that suggests some hope” for patients with DMD, says Dr. Ronald Victor, associate director of the Cedars-Sinai Heart Institute and the lead author of the study.

Victor administered standard clinical doses of Viagra or Cialis to 10 boys with DMD ages 8 to 13. After testing the boys’ responses on handgrip exercises before and after doses, Victor concluded that the improvement in blood flow in exercising muscles was “marked, immediate, and dose-dependent,” according to the study. The results were similar whether Viagra or Cialis was administered, though Victor says Cialis is preferable because its effect on muscles last 24 hours (compared to one hour with Viagra) and it more specifically targets what they want to achieve with DMD patients.

By showing that Viagra and Cialis can be used to “normalize blood flow” in DMD patients, Victor considers the study a solid first step. He is already working on a larger international study to see if the erectile dysfunction medicines can have a long-term effect on DMD. “Now, we need to see how to protect the muscle and slow the progression of the disease. By age 15, most boys are in a wheelchair or can’t walk. We'd like to see that prolonged by many years,” he says. He is also hoping that Cialis and Viagra will stall the degeneration of heart muscle function, as the ultimate cause of death in DMD is usually heart failure.

Though more research is needed to determine how valuable Viagra and Cialis treatments will be in the long term for those with DMD, they are already proving to be a step in the right direction for a disorder with limited treatment options—and they are already readily available. “The idea is to repurpose an old drug for an additional disease, so that there's no money and time delay when it comes to drug discovery. It would be really efficient,” Victor says.

When asked if any of the parents of his patients hesitated about putting their young sons on medicines made to treat a sexual disorder, Victor says it was never a concern. Although one patient had an erection that lasted six hours and another patient had one that lasted four, they were neither painful nor dangerous, which is really the prime concern for parents watching their sons struggle through such a horrible disorder.

“It’s such an awful disease. Every day they are fighting against the clock to see if researchers will find something to help their children,” says Victor. “The parents see it as a mild embarrassment factor compared to the potential hope to help their boys.”