Viagra or Cialis could treat Duchenne muscular dystrophy

Erectile dysfunction (ED) medications for adult males such as Viagra and Cialis could be beneficial for boys suffering with the muscle disease Duchenne muscular dystrophy (DMD), according to the findings of a new study.

The small study – published online May 7 in the journal Neurology – included 10 boys between the age of eight and 13 with the disease, and the researchers discovered that popular male impotence drugs Viagra and Cialis worked at boosting blood flow to the impaired and weakened muscles in the boys.

“Boys with Duchenne muscular dystrophy have a blood flow abnormality – delivery of blood and oxygen to their muscles – that does not increase the way it should during mild exercise,” commented lead researcher Dr Ronald Victor, the associate director of the Cedars-Sinai Heart Institute in Los Angeles.

Not a commonly known ailment, DMD is a genetic condition that may be inherited which causes muscle weakness and begins during childhood. Signs of DMD are when the child has difficulty standing up, climbing or running. It primarily effects boys in their early childhood and unfortunately they can only expect to live into their 20s or 30s. Some girls may also carry the Duchenne gene.

Treatment with medication such as corticosteroids can slow down muscle degeneration and provide protection for heart and lung function, but they have no impact on the abnormal blood flow. In addition, there are more than a quarter of patients unable to tolerate steroids or their side effects.

For the study, scientists based at the Cedars-Sinai Institute looked at the impact ED medications had for the 10 boys with DMD and experiencing blood flow problems. All the boys were initially using steroids and they were subsequently compared against 10 healthy boys in the same age group.

Those with DMD were still able to walk, but some used a wheelchair or scooter too. Their blood pressure was taken during rest and whilst performing a handgrip exercise. Despite taking steroids, the boys with Duchenne were found to have abnormal blood flow.

Tests were conducted again after the boys were given a single dose of either sildenafil (commonly known as Viagra) or tadalafil (commonly known as Cialis). After a fortnight, those given sildenafil were switched to tadalafil, and vice versa, with tests carried out yet again.

Treatment with both drugs resulted in improved blood flow in the boys with Duchenne, even equalling that of the healthier boys.

In regards to side effects from taking what are obviously adult-only medications, Dr Victor says: “A few boys in our study had erections after taking these drugs. The erections were not painful and not dangerous and resolved spontaneously without treatment.”

It is not known if the anti-impotence drugs will slow progression of the disease and Dr Victor believes a much larger trial could help solve this mystery.

“The findings in this small study led to a large clinical trial, which is enrolling now in the U.S. and abroad, to see if 48 weeks of treatment with once-daily Cialis will slow the decline in walking ability in 7- to 14-year-old boys with Duchenne. The findings offer some hope, but we need to wait for the results of the large treatment trial to see if daily treatment with Cialis has a clinically meaningful benefit for boys with this form of muscular dystrophy.”