One of the most common causes of erectile dysfunction is that which is associated with vascular insufficiency and an inadequate blood supply to the penis. Various entities such as hypertension, diabetes, dyslipidemia, and the use of tobacco have all been linked as being causative to creating the vascular injury that is causative for erectile dysfunction. Atherosclerosis in the very narrow arteries of the penis may be an early indicator of a diffuse systemic process that is affecting other blood vessels that can result in serious outcomes (myocardial infarct, stroke).
In 1989, scientists at Pfizer discovered sildenafil which is a substance that inhibits the phosphodiesterase 5 (PDE-5) enzyme, which is found in many body tissues, but is found in highest concentrations in penile tissue. This original research centered on the premise that with the inhibition of this substance, coronary arteries would dilate, thus easing symptoms of angina (chest pain due to insufficient blood flow to the heart). Studies were conducted that consisted of administering this substance to patients with angina, and the results were not very encouraging. But a fair number of patients who were administered the large dosages in this study reported an increased likelihood of obtaining an erection.
A biochemical cascade of events occurs that promote erections. This begins with the release of nitric oxide and ultimately results in cyclic GMP (C-GMP). Sildenafil inhibits the breakdown of c-GMP, a chemical that causes the relaxation of smooth muscle cells. By blocking the breakdown of this substance cGMP is allowed to accumulate in penile tissue, therefore allowing maximal relaxation of the smooth muscle in the penis. This results in increased blood flow and an erection. It is this biochemistry that has allowed 3 pharmaceutical manufacturers to introduce medications that help overcome erectile dysfunction.
Published On: August 07, 2006