Megalis 20 mg contains the active ingredient tadalafil, which is a phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction (ED) in men. Tadalafil works by inhibiting the enzyme phosphodiesterase type 5 (PDE5), which is responsible for the degradation of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the penis. By inhibiting PDE5, tadalafil increases the levels of cGMP, leading to smooth muscle relaxation and vasodilation, which enhances blood flow to the penile tissues, facilitating an erection. https://www.genericday.com/megalis-20-mg.html