Difelikefalin for Itching in Hemodialysis Patients With Chronic Kidney Disease

Chronic kidney disease-associated pruritus (CKD-aP), alternatively termed uremic pruritus (UP), represents a frequent, distressing, and often incapacitating clinical manifestation among individuals diagnosed with chronic kidney disease (CKD) or end-stage renal disease (ESRD). Characterized by persistent, intense itching-typically generalized but occasionally localized-CKD-aP disproportionately affects patients undergoing hemodialysis, with epidemiological studies reporting a variable prevalence ranging from 22% to 84% in this population. Notably, a substantial subset of these patients, approximately 20-40%, experience moderate-to-severe pruritus, which significantly diminishes their quality of life. The impact of CKD-aP extends beyond physical discomfort. The condition is associated with chronic sleep disturbances such as insomnia, fatigue, and dermatological complications including excoriations, lichenification, and secondary infections due to repeated scratching. Psychosocially, patients often experience emotional distress, social withdrawal, and stigmatization related to visible skin lesions, which may worsen underlying mental health conditions such as anxiety and depression. Additionally, CKD-aP has been associated with increased mortality in dialysis patients, including higher risks of cardiovascular events and infections, suggesting a link with systemic inflammation and immune dysregulation. There is a clear need for effective treatment options for CKD-aP. Current off-label therapies include antihistamines, topical corticosteroids, gabapentin, and pregabalin. While some of these treatments may reduce itching, their side effects can limit their use in this population. The pathogenesis of CKD-aP remains incompletely understood. Proposed mechanisms include metabolic disturbances, immune system dysregulation, and imbalance in the endogenous opioid system, particularly involving peripheral kappa opioid receptors. Difelikefalin is a peripherally acting, selective kappa opioid receptor agonist that exerts antipruritic effects through activation of receptors on peripheral neurons and immune cells. Its hydrophilic peptide structure limits its ability to cross the blood-brain barrier, thereby reducing central nervous system effects. Difelikefalin has been approved as the first medication specifically indicated for CKD-aP in patients undergoing dialysis and has demonstrated efficacy in phase 3 clinical trials. It is currently recommended as a first-line treatment for moderate-to-severe CKD-aP in dialysis patients where available. Despite promising results, some limitations remain. A proportion of patients do not achieve clinically meaningful improvement in itch intensity or quality of life. Clinical trials have demonstrated significant benefits, but response variability persists. The safety profile of difelikefalin is dose-dependent. Common adverse effects include nausea, vomiting, dizziness, diarrhea, and gait disturbances. A dose of 0.5 μg/kg appears to provide the most favorable balance between efficacy and safety. Although difelikefalin is a promising treatment option, current evidence remains limited, and additional well-designed randomized controlled trials are needed to confirm its effectiveness. While most existing studies have been conducted in Western populations, data from low- and middle-income countries such as Bangladesh are limited. The prevalence of CKD in Bangladesh is high, affecting millions of individuals, with a significant number progressing to end-stage renal disease annually. This study aims to evaluate the superiority of difelikefalin over placebo in reducing pruritus severity among patients undergoing maintenance hemodialysis in a tertiary-level teaching hospital in Bangladesh.