Cialis shows promise in treating muscle condition

The same drug that helps men achieve erections might also help boys with a rare and debilitating muscular condition improve their strength.

A recent study showed that the drug Cialis, which is widely used for erectile dysfunction in men, might be effective in treating Becker muscular dystrophy in boys.

Repurposing drugs — in other words, using them for conditions for which they weren't originally intended — is becoming increasingly common in medicine. That's especially true for rare, genetic conditions with limited therapies.

Dr. Barry Byrne is a professor of pediatrics and molecular genetics and microbiology at the University of Florida and one of the authors of the study.

"In many ways in genetic diseases, we've kind of imagined one treatment that is curative," he said. "Practitioners are starting to recognize in oncology, for example, that there are many different strategies."

Cialis, also known as tadalafil, works by increasing blood flow to muscles — to the penis in the case of erectile dysfunction — where it blocks a chemical responsible for reversing an erection. In patients with BMD, in which there is a progressive slackening of the body's muscles, Cialis opens up blood vessels by inhibiting the destruction of the intracellular messenger that activates a protein affected by the disease.

"The drug offsets the inability of that protein to modulate blood flow and muscle," said Byrne, who is also director of the UF Powell Gene Therapy Center.

Kristine Crane is a Gainesville Sun staff writer.