Difelikefalin is an orally bioavailable second-generation peptide. It is an investigational peripheral kappa opioid receptor agonist. Difelikefalin significantly reduced moderate to severe chronic itching while achieving across-the-board clinically meaningful improvements in quality of life measures in patients with hemodialysis-associated pruritus in a phase 2 study. In a phase 2 clinical investigation, difelikefalin was safe, well tolerated and showed robust analgesic activity for postoperative pain in female patients undergoing laparoscopy, with a significant reduction in post-operative morphine consumption and opioid-related side effects. Now difelikefalin is in phase III clinical trials for the treatment of post-operative pain and pruritus.