The medication Fildena 150 is used to treat erectile dysfunction (ED) in men. Sildenafil citrate increases blood flow to the penis, resulting in a firmer and longer-lasting erection. It is a medication that is a PDE5 inhibitor. The Red "Triangle Pills" is sildenafil citrate used to treat impotence or erectile dysfunction in males. Sildenafil citrate, the active ingredient in Fildena, is a selective inhibitor of the type 5 (PDE5). Selective inhibition of this enzyme relaxes the smooth muscles of the penile region.