Erectile Dysfunction Drugs like Viagra (sildenafil) Levitra (vardenafil) and Cialis (tadalafil) have become household names and have provided answers to many men. 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 says it is becomng increasingly important for Doctors of various specialities to become proficient in the mechanisms and systemic effects of these medications.
A recent research by Schwarz and colleagues to determine about the effects of long-term use of this class of drugs on various organ systems found that the drugs, called phosphodiesterase-5 inhibitors (PDE-5i), produce mostly beneficial results, and not just for erectile dysfunction. The FDA recently approved a reformulation of sildenafil 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. 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 drugs have been on the market for several years now and there have been no reports of negative long-term effects, adds Schwarz.
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 drugs' constraint of the enzyme's action 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.
According to the research PDE-5 inhibitors can be effective in treating erectile dysfunction even for many men who also have diabetes, those who are older, and those who have co-existing ischemic heart disease (reduced blood flow to the heart caused by plaque buildup in the arteries). Furthermore, say the authors, "since PDE-5 is found in smooth muscles of the systemic arteries and veins throughout the body, use of PDE-5i has been associated with various cardiovascular effects."
"The original intention was to develop PDE-5 inhibitors as a treatment for angina, chest pain that occurs when the heart is starved for oxygen," Schwarz said. "As such, their effects on the heart appear to be all beneficial. Nitrates and other substances commonly used to improve blood flow and oxygenation to the heart muscle have a side effect that we call the 'steal phenomenon,' in which blood is taken away from underperfused (flow-restricted) areas to improve blood flow in normal areas. In contrast, PDE-5 inhibitors actually improve blood flow even in areas where there is a blockage of an artery, thereby having a protective effect on the heart muscle."
Speaking about the drugs' potential impact on visual function that became a matter of controversy when a suspected link between PDE-5 inhibitors and vision loss led to lawsuits filed last year against the maker of Viagra, the researchers observed that analysis of clinical trial data in more than 13,000 men and on more than 35,000 patient-years of observation found occurrence of the visual disorder to be similar to that of the general population.
The research concluded, "Experimental and human studies indicate that PDE-5 inhibitors are effective and well tolerated, and there is evidence that they are not being used to their utmost potential. We suggest that these drugs may prove beneficial in treating a wide variety of disorders."
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# posted by Network @ 2:29 AM
