The mechanism of action of Filagra is straightforward yet highly effective. When a man is sexually aroused, the body releases nitric oxide, which enhances the production of cyclic guano sine monophosphate (camp). Camp causes the smooth muscles in the penis to relax, allowing blood to flow more freely and resulting in an erection. PDE5 breaks down camp, but Sildenafil, the active ingredient in Filagra, inhibits this enzyme, thereby prolonging the effects of camp and enhancing the ability to achieve and sustain an erection.