What is Cialis (tadalafil)?
Cialis is in a class of medications known as PDE-5 inhibitors, which are used to treat cases of male impotence. Cialis is a fairly new impotence drug and has only just come onto the market. The UK is the first country in the world to be able to offer Cialis to its residents. Viagra and Cialis
Originally Pfizer created 'Sildenafil'. It was designed as a drug for high blood pressure and angina, but it wasn't very successful. When during testing men refused to give their samples back, the researchers knew they were onto something!

So, they put it into a tablet, called it Viagra, and made millions. Cialis came about when the people at Eli Lilly & co, (who make Prozac) and ICOS, teamed up together as Lilly ICOS. They took the Sildenafil molecule and figured ways to make it more effective. Once done, they called it Tadalafil, and gave it the trade name Cialis.