Viagra, Sildenafil citrate (international nonproprietary name), is a drug from the class of phosphodiesterase type 5 (PDE5) inhibitors developed by the pharmaceutical company Pfizer. This medicine is indicated for erectile dysfunction and pulmonary arterial hypertension. It is marketed by the company under the name Viagra in 25 mg, 50 mg and 100 mg tablets, and under the name Revatio in 20 mg tablets.
Viagra’s exclusive patent was supposed to fall around June 20116, but it was not until June 21, 2013 that the patent expired in France and elsewhere in Europe with a few days delay. About fifteen generics should thus be placed on the market. After the loss of its patent, Pfizer decided to produce in several European countries, including France, its own generic, under the name Sildenafil Pfizer (also presented under the name Verventi8). It will be manufactured in Amboise on the same site as Viagra.
Sildenafil citrate is a specific inhibitor of cyclic GMP phosphodiesterase type 5 (PDE5) in smooth muscle, where PDE5 is responsible for the degradation of cGMP. Sildenafil citrate causes the accumulation of cGMP in smooth muscle cells, resulting in relaxation and vasodilation of the latter. In patients with pulmonary hypertension, this leads to vasodilation of the pulmonary vascular bed and, to a lesser extent, to vasodilation in the systemic circulation. In patients with erectile dysfunction, sildenafil citrate increases the effect of nitric oxide (NO) by inhibiting PDE5 in the corpus cavernosum. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil citrate causes increased levels of cGMP, resulting in relaxation of smooth muscle in the penis and increased blood flow to the penis. corpus cavernosum.
