Fildena 150 is a pill that contains the active ingredient sildenafil citrate. It is a type of phosphodiesterase type 5 (PDE5) inhibitor. PDE5 inhibitors are drugs that increase blood flow to the male genitalia, thereby increasing erectile function. This medicine works by blocking the activity of PDE5, which increases the level of cyclic guanosine monophosphate (cGMP) in the body. This relaxes the smooth muscles of the penis and improves blood flow to the penis, which creates an erection and allows you to enjoy sex for longer.