Viagra is a drug to treat erectile dysfunction (ED, Impotence). Viagra dosage is from 25 to 100 mg taken, as needed, approximately 1 hour before sexual activity, but only once a day.
Sildenafil citrate, commonly known as Viagra, is a drug used to treat male erectile dysfunction (impotence), developed by the pharmaceutical company Pfizer The pills are blue with the words -Pfizer- on one side and -VGR 100- on the other. Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in the corpus cavernosum, resulting in increased inflow of blood and an erection.