The class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors includes Vidalista 40. By relaxing the blood vessels in the penis, its active ingredient, tadalafil, increases blood flow and facilitates erection. With a maximum half-life of 36 hours, Vidalista 40 has a longer half-life than other drugs in its class. Because it works for a longer period of time, it's known as "the weekend pill."
