Pharma Blog Online

Tadalafil (Cialis) is a medicine that should be accepted orally. This drug is applied for the treatment of impotence (the inability to attain or maintain a penile erection). It belongs to in a class of drugs called phosphodiesterase inhibitors. This class also includes sildenafil (Viagra) and vardenafil (Levitra). Erection of the penis is caused by the filling of the penis with blood. Filling occurs because the blood vessels bringing blood to the penis extand in size, that’s why the penis is filled by a plenty of blood. At the same time, the blood vessels that carry blood away from the penis reduce in size and remove less blood from the penis. Sexual stimulation that leads to an erection causes the production and emission of nitric oxide in the penis. The nitric oxide causes an enzyme called guanylate cyclase which is necessary for production of cyclic guanosine monophosphate (cGMP). This chemical compound is responsible for extanding and redusing the size of the blood vessels carrying blood to and from the penis. These transformations lead to erection. Then the cGMP is destroyed by another enzyme called phosphodiesterase-5, the blood vessels return to their normal size, blood leaves the penis, and the erection ends. Tadalafil (Cialis) averts cGMP from destroying by phosphodiesterase-5 so that cGMP stays around longer. The longer existence of cGMP causes more prolonged filling of the penis with blood. Tadalafil (Cialis) was approved by the FDA in November, 2003.