Abstract
Approximately 150 million men worldwide experience erectile dysfunction (ED) whereby they are unable to achieve and maintain an erection adequate for satisfactory sexual performance. ED has a considerable impact on quality of life. Tadalafil (Cialis( trade mark ), Eli Lilly & Co./ICOS) is a novel effective and safe phosphodiesterase type 5 inhibitor, a secondary messenger for the smooth muscle relaxing effects of nitric oxide, which plays a central role in the vasodilation of erectile tissues. It has a longer half-life than sildenafil. As head-to-head comparative trials are lacking, it is not clear what tadalafil offers over sildenafil. In terms of marketing, much is made of the 'spontaneity' achievable because of the (relatively) longer half-life of tadalafil.
