Tadalafil in Vidalista 40  works by acting on blood vessels in different regions of the body. It works by blocking the enzyme phosphodiesterase (PDE5), which in turn prevents the breakdown of cGMP. This is responsible for the relaxation of the blood vessels. When the drug acts on the blood vessels in the pelvic region, more blood flows through the dilated vessels. The blood vessels in the p*nis are relaxed and therefore more blood is pumped into the tissues of the p*nis, causing an erection.