VIAGRA [Sildenafil citrate] An Overview

VIAGRA [Sildenafil citrate] is the only approved and effective oral agent for the treatment of erectile dysfunction. Before that a few lines on erectile dysfunction.
Erectile dysfunction [Impotence] is a condition in which erection the penis cannot be achieved during sexual intercourse/masturbation. There are many causes for erectile dysfunction. The most common cause of being increasing age. Other conditions can be: - Diabetes Mellitus - Hypertension - Heart Disease - Atherosclerosis - Lower spinal cord injury - Cancer prostate - Psychogenic - Stress
Erection is achieved when there is increased blood flow to penis and hence the main organic cause is disturbance of blood flow to and from the penis.
Coming back to VIAGRA [Sildenafil citrate], Viagra is a selective and potent inhibitor of cyclic guanosine monophosphate [cGMP] specific phosphodiesterase type 5 inhibitor [PDE5] which is the predominant phosphodiesterase isoform found in the penis. It is administered in doses of 25, 50 and 100 mg, and enhances erection after sexual stimulation. The onset of action is around 60-90 mins.
Sildenafil (compound UK-92,480) was synthesized by a group of chemists working at Pfizer’s Sandwich, Kent research facility in England. It was initially studied for use in hypertension and angina pectoris. The first clinical trials were conducted in Morriston Hospital in Swansea. Phase I clinical trials under the direction of Ian Osterloh suggested that the drug had little effect on angina, but that