Filitra 40 mg is a prescription medication used to treat erectile dysfunction (ED). The active ingredient in Filitra is Vardenafil, which works by inhibiting the enzyme phosphodiesterase type 5 (PDE5). PDE5 is responsible for breaking down cGMP, a substance that helps relax blood vessels and increase blood flow to the penis. By blocking PDE5, Vardenafil helps maintain higher levels of cGMP, which results in improved blood flow and, consequently, an erection in response to sexual stimulation.