Zhewitra 20 mg contains Vardenafil, which is part of a class of medications known as phosphodiesterase type 5 inhibitors (PDE5 inhibitors). These medications work by blocking the action of the enzyme PDE5, which normally degrades cyclic GMP (cGMP), a molecule responsible for regulating blood flow in the penis. By inhibiting PDE5, Vardenafil helps maintain higher levels of cGMP, leading to relaxed blood vessels and improved blood flow to the penis during sexual arousal.