In order for an erection to occur it is necessary for blood to be pumped to the penis to make it hard and have sexual intercourse. Because of certain physical conditions this may be impossible to achieve. Because of research and subsequent development by Lilly ICOS of their drug Cialis these conditions can be overcome.

Cialis is member of a family of drugs called PDE5 enzyme inhibitors. Why is this important? It is know that cyclic guanosine monophosphate (cGMP) was the key to sustaining an erection. When a man gets sexually stimulated a chain reaction occurs in the tissue of the penis that results in elevated levels of cGMP. Providing that there are sufficient levels of cGMP, the penis can remain erect. The more cGMP the more robust the erection. Cialis blocks the enzyme PDE5 which is responsible for neutralization of cGMP. Cialis is very highly selective inhibitor of PDE5. What is important about Cialis is that it does not on its own cause an erection, Cialis blocks the degradation of cGMP produced in reaction to sexual stimulation. If you are not being sexually stimulated there is no cGMP to protect so Cialis remains in the background.

Cialis is easily absorbed into the bloodstream and it can be taken from 30 minutes up to 12 hours prior to sexual activity, therefore Cialis is active for between 24 and 36 hours. The advantage is that Cialis, because of its unique onset and duration periods, can be taken many hours before sexual activity is contemplated.

The bottom line on how Cialis works can be summarised as follows: When an erection goes limp, you have PDE5 to thank for this. Cialis inhibits this enzyme preserving cGMP, therefore aiding erections and durability. It is fast acting and has the unique ability to remain active for up to 36 hours after taking the tablet.