Tadalafil, a phosphodiesterase type 5 (PDE5) inhibitor in Tedderis 20 (generic cialis), is used to treat erectile dysfunction in men (impotence). When taken before planned sexual activity, tadalafil in Tadarise prevents the breakdown of a chemical called CGMP (via the enzyme PDE5) produced in the erectile tissues of the penis during sexual arousal, and this action causes the blood flow to the penis to erupt.