By inhibiting PDE5, viagra 600 effectively increases the levels of cGMP, enhancing and prolonging erections in men suffering from ED. PDE5, however, breaks down cGMP, thus inhibiting the ability to achieve or maintain an erection. The drug is effective only with sexual stimulation, as it relies on the initial release of nitric oxide by the body. This leads to prolonged blood flow and, consequently, a sustained erection.

Viagra works by inhibiting the action of PDE5, thereby increasing the levels of cGMP in the corpus cavernosum. PDE5 breaks down cGMP, thus regulating blood flow and causing the erection to subside. It is important to note that sexual stimulation is required for Viagra to be effective, as it does not initiate an erection but rather makes it easier to develop and maintain one when there is arousal. However, during clinical trials, researchers discovered that it had a profound effect on erectile dysfunction (ED), which led to its repositioning as a treatment for this condition.

Viagra, scientifically known as sildenafil citrate, was initially developed as a medication for treating high blood pressure and angina, a type of chest pain associated with heart disease. Since its approval by the FDA in 1998, Viagra has become one of the most well-known and frequently prescribed drugs for erectile dysfunction worldwide. Introduced to the market in 1998, Viagra was the first oral treatment approved by the FDA for erectile dysfunction.

Its introduction was a major breakthrough and it has since become a cultural phenomenon, often discussed openly in the media and in popular culture, which was unusual for any medication related to sexual health before its advent. Viagra is administered orally, typically in dosages ranging from 25 mg to 100 mg. It is advised to take the medication about one hour before sexual activity, and its effects can last up to four hours. However, it is important to note that Viagra does not increase sexual desire; it only helps to maintain an erection when sexual stimulation occurs.

It has shown potential in treating pulmonary arterial hypertension (PAH), a rare but serious disease that affects the blood vessels in the lungs. For this indication, the drug is marketed under the name Revatio. Research is ongoing into other possible therapeutic uses, including its effects on heart disease, doxycycline online without prescription diabetes-induced kidney damage, and even certain types of cancer. Beyond its use in erectile dysfunction, Viagra has also been explored for other medical conditions.

Common adverse reactions include headaches, facial flushing, indigestion, nasal congestion, and, less commonly, changes in vision such as increased sensitivity to light or blurred vision. The drug is generally safe for most men, but it is not devoid of side effects. More serious but rare side effects can include priapism (a painful erection lasting longer than four hours), sudden hearing loss, or vision loss.