Men’s sex pills may be giving them a new lease on life, but recent tests have shown that the chemicals that get grandpa going may also give a boost to boys with a degenerative muscle condition. Found in about one in 3,600 young males in the U.K., life-shortening Duchenne muscular dystrophy (DMD) is caused by a mutation in the dystrophin gene, the largest gene found on the human X chromosome. While both sexes can carry the mutation, females rarely show signs of it.
Now an encouraging preliminary study published online in the May 7 edition of the medical journal Neurology, has shown that the drugs used in the men’s sex pills Cialis and Viagra, tadalafil and sildenafil, improve blood flow to the muscles of boys suffering from Duchenne muscular dystrophy (DMD) in much the same way as they give penile blood flow a boost in men with erectile dysfunction.
Because the trials were administered to a group of 10 boys for only a short period of time, the results have been described by the team’s leader, cardiologist Ronald Victor, as encouraging but far from conclusive at this stage. Victor, of the Cedars-Sinai Medical Center in Los Angeles, believes the results were striking. He examined the boys’ muscles after the treatment and concluded that there had been a complete correction of the abnormal blood flow.
The root problem of DMD is caused by dystrophin, a protein found in the membranes of the muscle cells that get eliminated by the disease. In 2000, Victor’s research team found that blood flow problems for DMD patients was caused by too little nitric oxide, a chemical that able to make blood vessels relax during exercise, thereby increasing blood flow and oxygenation.
The chemicals in men’s sex pills have a good effect in boosting the blood flow of boys with DMD, because nitric oxide is the same chemical that makes the muscles in the penis relax and allow it to become engorged with blood. In men who have erectile dysfunction, the cause is most often an insufficiency of nitric oxide, and Viagra and Cialis correct the imbalance.
Victor’s team first tested the drugs on mice and then moved on to human trials that led to the publishing of the results in 2012 that showed how tadalafil restored the blood flow in boys who have Becker muscular dystrophy, a similar but less dangerous condition. Gripping exercises for boys with DMD were noticeably easier for them after just one dose of tadalafil or sildenafil, which enabled the major artery of the arm and the blood vessels in the muscles of the forearm to function normally, or like those of their healthy peers.
Victor said that steroids, along with cardiac-protecting blood pressure medicines, are often being prescribed earlier and earlier for boys with DMD in an effort to try to delay the worst effects of the disease by at least a few years. However, he said they are ineffective when it comes to the sort of dysfunction that prevents muscles from getting proper oxygen.
In contrast, he said, one dose of the tadalafil or sildenafil found in men’s sex pills had an immediate effect in boosting the blood flow of the boys in the study. As they are proven drugs that are already on the market, he felt additional testing would confirm their suitability, and that repurposing the drugs for DMD patients could quickly transform clinical practice.
By Keith Allen