Sildenafil citrate is issued in doses of 25, 50, and 100 mg pills, which contain the corresponding amounts of the drug Sildenafil Citrate.

The active properties that make sildenafil so effective is its ability to increase the influx of blood to the penis, which causes a natural erection. sildenafil has a positive effect only when the man experiences sexual arousal and the drug does not prevent the penis from becoming flaccid after intercourse. In fact, a man may well maintain his erection or have the ability to get erect several times over the course of a 12 hour period. In other words, sildenafil is just enhancing the natural reactions of an erection. This explains why sildenafil has gained such worldwide popularity.

The discovery and invention of sildenafil has been touted as the "third greatest accidental invention" in medicine after the X-ray and penicillin. All three discoveries brought to their authors the Nobel Prize. The scientists who invented sildenafil received this award as well the fall of 1998. Although certainly this wasn't their objective.

The history of sildenafil began in 1992 in Sandwich, England during a long period of pharmacological research for Pfizer Drugs Inc. Researchers carried out clinical tests of a new medical substance - Sildenafil Citrate, which was developed as a remedy for the treatment of a variety of cardiac illnesses.

Scientists hypothesized that Sildenafil Citrate would cause an increase in blood-flow to the cardiac muscle in addition to lowering a person's blood pressure. However, they found out that Sildenafil Citrate had a significant influence neither on blood circulation in the cardiac muscle (myocardium), nor on blood pressure. The drug did do wonders for a man's erection however!

Researchers from Pfizer Drugs Inc. were surprised by the unexpected properties of Sildenafil Citrate and managed to create a powerful remedy for treatment of erectile dysfunction. They named the drug sildenafil - a play on the words "Vigor" (power, energy, force) and "Niagara" - the most powerful falls in Northern America.

Long clinical tests began in 1993 proved demonstrated a high efficiency of sildenafil as a treatment for impotence. On March 27th, 1998, the Food and Drug Administration (FDA) of the United States approved sildenafil. In worldwide research on the effect of sildenafil on erectile dysfunction, more than 3000 men from the ages of 19 to 87 years were studied. Results of these research showed that sildenafil was effective for recovery of erectile function and increased the number of sexual acts for the majority of patients, including those with diabetes, with spinal cord damage, and those patients taking a number of other medicines at the same time.

There is no medicine that is capable of curing all the kinds of erectile dysfunction. sildenafil is not a panacea. It can help many but, unfortunately, not all the patients. Only a doctor can understand the nature of erectile dysfunction in his patients and he is the only one who can prescribe appropriate treatment.