Tadalafil, the active ingredient in Vidalista 60 mg, works by inhibiting the PDE5 enzyme, which regulates blood flow in the penis. By blocking PDE5, tadalafil increases the levels of cyclic guanosine monophosphate (cGMP). This chemical relaxes the smooth muscles in the blood vessels of the penis, allowing for increased blood flow during sexual stimulation, which facilitates the achievement and maintenance of an erection.