May 8, 2014
Treating Deadly Duchenne Muscular Dystrophy With Viagra, Cialis
Brett Smith for redOrbit.com - Your Universe Online
Cialis and Viagra are typically prescribed to treat erectile dysfunction in men, but a new study has shown that these drugs could be used to treat a deadly disorder known as Duchenne muscular dystrophy (DMD).
DMD is a genetic disorder in males marked by muscle weakness beginning in early childhood and quite often causing deformity of the forearms, legs and spine. Cardiovascular and respiratory muscles usually begin to decline when those with the condition become teenagers. Although anabolic steroid medicines – which are not well accepted by the body – and other treatments may relieve symptoms and postpone decline, a disease-specific therapy currently does not exist and patients seldom survive into middle age.
Males with DMD either lack or have low levels of the protein called dystrophin, which helps sustain healthy muscles. Patients’ muscles are starved of nitric oxide, which is a molecule that signals blood vessels to relax during exercise, boosting blood flow.
In the new study, which was published in the journal Neurology, researchers found an individual dose of drugs usually given for erectile dysfunction or pulmonary high blood pressure levels remedied malfunctioning blood vessel mechanisms and restored circulation of blood to exercising muscles.
"The effects were immediate and dramatic, raising the question: If a single dose restores blood flow to muscle while the drug is in the patient's system, could ongoing tadalafil administration provide sustained benefits, possibly preserve muscle and slow disease progression? If so, this would offer a new therapeutic strategy for DMD, and we have launched a randomized Phase III clinical trial to find out," said Dr Ronald Victor, an author of the new study and director of the Cedars-Sinai Center for Hypertension.
For the study, the team recruited ten boys aged eight to 13 with DMD who were taking corticosteroids first and ten healthy boys of the same age. All of the participants with DMD were able to walk, however some regularly used a wheelchair or mechanized scooter.
The circulation in all of the volunteers' muscles was assessed when they were resting and when they were performing a handgrip exercise. The tests revealed that the boys with DMD had circulation problems, even though they were getting corticosteroids.
Next, participants with DMD were given tadalafil (Cialis) or the drug sildenafil (Viagara) and the hand-grip trials were repeated. After a two-week waiting period, the boys were given the other drug and were tested again.
The researchers found that the boys' blood flow reaction during exercise was equivalent to that of the boys who did not have the disease.
"Steroids and cardiac-protective blood pressure medication are increasingly prescribed at early ages for patients with Duchenne muscular dystrophy in an effort to delay by a few years the most devastating effects of the disease. But these treatments have no effect on the blood vessel dysfunction that prevents muscles from getting the oxygen they need," Victor said. "In contrast, in our study, a single dose of tadalafil or sildenafil had an immediate effect.”
“If additional study confirms their benefits, repurposing the drugs for muscular dystrophy patients could quickly transform clinical practice,” he said.