With Viagra and the subsequent introduction and marketing of Levitra- (vardenafil) and Cialis - (tadalafil), many men have found answers to a once-unmentionable condition

"As more and more patients seek therapy for sexual dysfunction, such as medication like Viagra it is increasingly important for clinicians in a wide range of specialties to become proficient in the mechanisms and systemic effects of the drug," said Ernst R. Schwarz, M.D., Ph.D., a cardiologist at Cedars-Sinai Medical Center who specializes in therapies for men who suffer from erectile dysfunction (ED) and have heart problems, diabetes, high blood pressure or other related conditions.

Schwarz and colleagues recently concluded a review of the medical literature, as well as their own research findings and clinical data, to determine what actually is known about the effects of long-term use of Viagra on various organ systems.

Their findings appears in the June, 2006 issue of the International Journal of Impotence Research. Studies so far suggest Viagra which are phosphodiesterase-5 inhibitors (PDE-5i), produce mostly beneficial results, and not just for erectile dysfunction.

The FDA recently approved a reformulation of Viagra for the treatment of primary pulmonary hypertension, a disease that tends to occur in young women, causing elevated blood pressures in the lung that can lead to heart failure and early death.

"When we look at all the different organ systems - the blood, the heart, the lungs, blood flow in the brain - there are hardly any negative side effects of Viagra.

In fact, just the opposite is true. There are beneficial effects for primary pulmonary hypertension, as well as for conditions such as heart failure and lack of oxygen in the heart," said Schwarz. "The only issue is that the data we have are from relatively short-term studies of Viagra.

Viagra has been on the market since 1998 and the other two PDE-5 inhibitors were approved by the FDA in 2003.

Therefore, we do not have multi-year follow-up studies. On the other hand, Viagra has been on the market for several years now and there have been no reports of negative long-term effects."

While there are some differences among the three medications, they have many properties in common and work by limiting the activity of the enzyme phosphodiesterase-5, which is found in tissues and vessels of the penis, blood platelets, and smooth muscle of blood vessels.

For the treatment of erectile dysfunction, the constraint of the enzyme's action by Viagra results in increased levels of cyclic guanosine monophosphate (cGMP) and nitric oxide (NO), biochemicals that promote smooth muscle relaxation and increased blood flow in erectile tissue.

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