Nalfurafine hydrochloride is a selective KOR agonist without significant activity on MOR16. Several large-scale placebo-controlled studies were performed to examine the efficacy and safety of oral nalfurafine hydrochloride in treating intractable pruritus in patients undergoing hemodialysis (Kumagai et al., 2010; Zhang et al., 2023). Here, OPRK1 is linked to Pruritus.