Drugs containing phosphodiesterase type 5 (PDE-5) inhibitors and traded as Viagra, Levitra and Cialis came as the expected wonder for males suffering from erectile dysfunction (translated to sexual impotence).

But a new research assessed how safe these products could be for diabetes patients.

The study verified whether sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are a safe and effective option for males suffering from diabetes.

Diabetic men involved in the study displayed improvements on all measures of erectile function, with an average difference of 26.7 % more "successful intercourse attempts" compared to placebo subjects, even if diabetes provokes many chronic conditions, such as heart disease and high blood pressure, but
also a three times higher probability to have erectile dysfunction than men who do not have diabetes.

"The results of our meta-analysis are not surprising, but give strength to the general notion that this class of drugs is efficient and safe for this specific wide population," said lead author Moshe Vardi, M.D., with the internal medicine division at Lady Davis Carmel Medical Center in Israel.

The 12 weeks research used 1,759 volunteers, half assigned to receive PDE-5 inhibitor therapy and the rest to be a placebo group. 80 % of the subjects had type 2 diabetes and the rest type 1 diabetes.

The research compassed volunteers of similar age, medical history, other prescribed medications or severity or duration of diabetes or erectile dysfunction.

PDE-5 inhibitors work by boostong the effects of nitric oxide, relaxing this way the smooth muscles in penis arteries during sexual stimulation, allowing increased blood flow into the penis and consequently erection. "PDE-5 inhibitors have been considered the mainstay of treatment for erectile dysfunction in the general population for many years," said Vardi. "Diabetics are prone to this complication, and the etiology of their erectile dysfunction is multifactorial, thus making their treatment a special challenge for physicians and other health care professionals."

The PDE-5 inhibitors presented as the most common side effects headache, flushing and flu-like symptoms, which were 4.8 times higher than in the placebo group. "These drugs can be taken on an 'as needed' basis, as their half-life spans from several hours to 48 hours at most," said Vardi. "Patients should also consult their physicians for drug-drug interactions and specific contraindications."

"I prescribe PDE-5 inhibitors every day to people with diabetes," said John Buse, M.D., director of the Diabetes Care Center at the University of North Carolina School of Medicine.

"But whether they are safe [in the long term] is the essential quandary of all medical care. We make our best guesses based on imperfect information, hopes and fears. And then we monitor progress. I am impressed that patients with diabetes in my practice in 2006 are living much better lives and perhaps longer lives than they did 10 years ago."