London - The anti-wrinkle jab Botox is being tested as a treatment for impotence.
In a new trial at Cairo University in Egypt, men with erectile dysfunction are having injections of botulinum toxin into the base of the penis to relax the muscles, so increasing blood flow to the area.
This follows animal experiments and a pilot study in men, which found a 50 percent increase in blood flow after the injections.
Erectile dysfunction - defined as the inability to have an erection that is satisfactory for sexual intercourse - is thought to affect half of men aged over 45.
While stress and other psychological and social factors play a role, in most cases the cause is vascular problems.
Men need a healthy blood supply to achieve an erection.
Normally, the arteries that supply the penis and the smooth muscle around it relax, increasing blood flow into the penis; pressure then traps the blood, maintaining the erection.
However, in men with erectile dysfunction, the blood vessels in the area are narrow, usually due to ageing or because they’ve become furred up with fatty deposits. This can significantly reduce blood flow in the penile tissue.
Lifestyle changes, such as losing weight, can help. Medications including Viagra or Cialis, which work by dilating the arteries that supply the penis, are also an option.
But some men do not respond to these drugs and they can also have side-effects (such as headaches and visual disturbances).
These medications also have to be taken in advance of sexual intercourse to reach an effective concentration. Botulinum toxin works by blocking signals in the nerves that supply muscles. As a result, the injected muscle can no longer contract.
While it is more often used to relax and soften forehead lines and crow’s feet, researchers in Egypt now use the jab in men with erectile dysfunction.
The new trial follows animal tests and a pilot study involving 24 men by the same team.
Results of the study, published in the journal Sexual Medicine Reviews earlier this year, showed that penile blood flow increased substantially in men given the botulinum toxin, but not in those given placebo jabs.
In a new trial, 160 men with erectile dysfunction will be given a single jab of botulinum toxin, or a placebo. Blood flow will be measured and sexual health compared for up to a month.
It’s thought the jab can provide a boost for several months, until the effect wears off.
Commenting on the technique, Professor Raj Persad, a consultant urologist with Bristol Urology Associates, said: "This is an interesting use of Botox. As with its use elsewhere, side-effects may occur. There is a theoretical risk that overuse could lead to permanent dilation of blood vessels and a permanent erection.
"Further clinical testing with scientific scrutiny will be necessary before adoption into clinical use.
"But this therapy may well one day take its place in the range of tailored treatments for erectile dysfunction."