Difelikefalin

Does Difelikefalin work?

Yes, in large controlled trials. The main trial had 378 people.

Approval rests on two randomized, double-blind, placebo-controlled phase 3 trials (KALM-1 and KALM-2) in hemodialysis patients with uremic itch. KALM-1, the trial cited here, randomized 378 patients and met its primary endpoint over 12 weeks. Nothing is missing for the approved use; what is missing is any controlled evidence for itch in people who are not on dialysis, which is where most online interest lies. ¹²

KALM-1 enrolled 378 adults on hemodialysis with moderate-to-severe itch. Researchers randomized them to difelikefalin or placebo after each dialysis session for 12 weeks. The main outcome was the share of patients whose weekly average itch score fell by at least 3 points on a 0-to-10 scale. That happened in 52% of the difelikefalin group and 31% of the placebo group. Itch-related quality of life also improved more on the drug. It was measured on the 5-D itch and Skindex-10 scales. ¹

The label pools KALM-1 with the similar KALM-2 trial, giving 424 patients per arm. Across both, the drug's advantage over placebo held. The FDA approved it on that basis. The placebo response was large, which is typical for itch trials. So the absolute gain is roughly one extra responder for every five patients treated. ¹²

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Reference information only, not medical advice. Drawn from the Difelikefalin article, fact-checked against the cited sources. No dosing anywhere on this site.