fildena is a drug used to treat erectile dysfunction? It is a PDE5 inhibitor. PDE5 inhibitors are drugs that block the action of the enzyme PDE5. This enzyme is responsible for the breakdown of cGMP, which is a molecule that is responsible for the relaxation of smooth muscles. Fildena works by inhibiting the action of PDE5, which allows cGMP to stay in the body for longer. This results in improved blood flow which leads to improved erections. Fildena Super Active | Tadarise 20mg