Fildena 100 Fildena 100 is extremely successful on men with erectile dysfunctions mainly due to its powerful active ingredient sildenafil Citrate. Sildenafil inhibits the PDE5 (cyclic guanosine monolaurin) enzyme and improves the production of cyclic guronic acid (CGH), a chemical in the male physiology that acts as a stimulus for sexual arousal and erection. The most important effect of CGH lies in its ability to relax the smooth muscle of the penis, allowing for more effective vascular flow and better blood supply into the penis.