In vitro studies have proven that sildenafil is selective for phosphodiesterase-5 (PDE5) . Its result is more powerful on PDE5 than on other recognised phosphodiesterases . Especially, There exists a ten-moments selectivity in excess of PDE6 and that is involved in the phototransduction pathway in the retina . Scientific efficacy https://williamg520yyw7.blog-eye.com/profile