Additionally, tadalafil is approximately 700-fold more potent for PDE5 than for PDE6, an enzyme which is found in the retina and is responsible for phototransduction.
Lisaks on tadalafiil ligikaudu 700 korda tugevama toimega PDE5 kui reetinas leiduva, fototransduktsiooni eest vastutava ensüümi PDE6 suhtes.