 In animals, nalfurafine produces anti-scratch, antinociceptive, sedative, and diuretic effects.Nalfurafine is an orally active, centrally acting, highly potent, selective full agonist of the κ-opioid receptor (KOR) (Ki = 75 pM; EC50 = 25 pM).As touched on above, nalfurafine shows atypical properties as a KOR agonist relative to other drugs.