Difelikefalin

Abstract: Introduction: Chronic kidney disease-associated pruritus (CKD-aP), or uremic pruritus, is a severely distressing condition that occurs in greater than 60% of patients undergoing dialysis. However, there are currently no FDA approved treatments for CKD-aP in the United States or Europe. Difelikefalin (DFK) is a kappa opioid receptor agonist with limited central nervous system (CNS) penetration that aims to fill this void by effectively and safely reducing itch in these patients.Areas covered: Through a review of the current literature (using PubMed and Google Scholar keyword searches of difelikefalin, CR845, pruritus, itch, opioids, hemodialysis, chronic kidney disease, uremic pruritus), the authors review DFK's mechanism of action and use published clinical trial data to evaluate its effectiveness in treating CKD-aP both individually and comparatively to other treatment alternatives.Expert opinion: DFK's IV formulation seems to provide safe, rapid-acting and effective itch reduction in hemodialysis patients without many of the negative mu opioid receptor (MOR)- or CNS- related side effects or drug-drug interactions of other currently available opioids. Its administration through IV bolus immediately after dialysis sessions at dialysis centers also increases availability to and ease of drug scheduling for this target population.

Abstract: Purpose of review This article provides a focused update on uremic pruritus, highlighting the latest evidence concerning the epidemiology, pathophysiology, and treatment options for this common and bothersome condition. Recent findings Half of dialysis patients and a quarter of those with nondialysis chronic kidney disease experience bothersome itch that reduces quality of life and is increasingly recognized to be associated with poor outcomes including mortality. The never expanded even in the original trial, which reported effective symptomatic relief with difelikefalin, has bolstered support for the role of an imbalance of μ and κ-opioid receptor activity in pruritogenesis. The role of a chronic inflammatory state increased cytokine levels and altered immune signaling in pruritogenic nerve activation continues to be elucidated with basic science, which paves the wave for future novel therapeutics. In the meantime, gabapentin appears to be the most evidence-based widely available uremic pruritus treatment, as long as care is taken with dosing and monitoring of side-effects. Summary Uremic pruritus remains a top research priority. Patients with uremic pruritus may be able to look forward to a new decade of understanding, knowledge, and novel treatment options for this burdensome condition. As difelikefalin and other potential agents come to market, cost-effectiveness assessments of these interventions will help determine if the widespread use of them is feasible amongst renal programs.

Abstract: Centrally administered bombesin induces scratching and grooming in rats. These behaviors were blocked by early benzomorphan kappa opioid receptor (KOR) agonists as reported by Gmerek and Cowan in 1984. This was the first evidence that KORs may be involved in the sensation of itch-like behaviors. Subsequent development of additional animal models for acute and chronic itch has led to important discoveries since then. For example, it was found that (a) gastrin-releasing peptide (GRP), natriuretic polypeptide b and their cognate receptors are keys for the transmission of itch sensation at the spinal cord level, (b) dynorphins (Dyns), the endogenous KOR agonists, work as inhibitory neuromodulators of itch at the spinal cord level, (c) in a mouse model for acute itch, certain KOR antagonists elicit scratching, (d) in mouse models of acute or chronic itch, KOR agonists (e.g., U50,488, nalfurafine, CR 845, nalbuphine) suppress scratching induced by different pruritogens, and (e) nalfurafine, CR 845, and nalbuphine are in the clinic or in clinical trials for pruritus associated with chronic kidney disease and chronic liver disease, as well as pruritus in chronic skin diseases.