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Clinical data
Trade namesKorsuva
Other namesCR845, FE-202845, D-Phe-D-Phe-D-Leu-D-Lys-[γ-(4-N-piperidinyl)amino carboxylic acid][1]
License data
Routes of
Drug classKappa opioid receptor agonist
ATC code
  • None
Legal status
Legal status
Pharmacokinetic data
Bioavailability100% (IV)[3]
MetabolismNot metabolized[3]
Elimination half-life2 hours[3]
ExcretionExcreted as unchanged
drug via bile and urine[3]
  • 4-amino-1-[(2R)-6-amino-2-[[(2R)-2-[[(2R)-2-[[(2R)-2-amino-3-phenylpropanoyl]amino]-3-phenylpropanoyl]amino]-4-methylpentanoyl]amino]hexanoyl]piperidine-4-carboxylic acid
CAS Number
PubChem CID
Chemical and physical data
Molar mass679.863 g·mol−1
3D model (JSmol)
  • CC(C)C[C@H](C(=O)N[C@H](CCCCN)C(=O)N1CCC(CC1)(C(=O)O)N)NC(=O)[C@@H](CC2=CC=CC=C2)NC(=O)[C@@H](CC3=CC=CC=C3)N

  • as salt: CC(O)=O.CC(C)C[C@@H](NC(=O)[C@@H](CC1=CC=CC=C1)NC(=O)[C@H](N)CC1=CC=CC=C1)C(=O)N[C@H](CCCCN)C(=O)N1CCC(N)(CC1)C(O)=O
  • InChI=1S/C36H53N7O6/c1-24(2)21-29(32(45)40-28(15-9-10-18-37)34(47)43-19-16-36(39,17-20-43)35(48)49)42-33(46)30(23-26-13-7-4-8-14-26)41-31(44)27(38)22-25-11-5-3-6-12-25/h3-8,11-14,24,27-30H,9-10,15-23,37-39H2,1-2H3,(H,40,45)(H,41,44)(H,42,46)(H,48,49)/t27-,28-,29-,30-/m1/s1

  • as salt: InChI=1S/C36H53N7O6.C2H4O2/c1-24(2)21-29(32(45)40-28(15-9-10-18-37)34(47)43-19-16-36(39,17-20-43)35(48)49)42-33(46)30(23-26-13-7-4-8-14-26)41-31(44)27(38)22-25-11-5-3-6-12-25;1-2(3)4/h3-8,11-14,24,27-30H,9-10,15-23,37-39H2,1-2H3,(H,40,45)(H,41,44)(H,42,46)(H,48,49);1H3,(H,3,4)/t27-,28-,29-,30-;/m1./s1

Difelikefalin, sold under the brand name Korsuva , is an analgesic opioid peptide used for the treatment of moderate-to-severe itching. It acts as a peripherally specific, highly selective agonist of the κ-opioid receptor (KOR).[3][4][5][6]

Difelikefalin was approved for medical use in the United States in August 2021.[2][7][8]

Difelikefalin acts as an analgesic by activating KORs on peripheral nerve terminals and KORs expressed by certain immune system cells.[3] Activation of KORs on peripheral nerve terminals results in the inhibition of ion channels responsible for afferent nerve activity, causing reduced transmission of pain signals, while activation of KORs expressed by immune system cells results in reduced release of proinflammatory, nerve-sensitizing mediators (e.g., prostaglandins).[3]


It is under development by Cara Therapeutics as an intravenous agent for the treatment of postoperative pain.[3][4][6] An oral formulation has also been developed.[6] Due to its peripheral selectivity, difelikefalin lacks the central side effects like sedation, dysphoria, and hallucinations of previous KOR-acting analgesics such as pentazocine and phenazocine.[3][4] In addition to use as an analgesic, difelikefalin is also being investigated for the treatment of pruritus (itching).[3][4][5] Difelikefalin has completed phase II clinical trials for postoperative pain and has demonstrated significant and "robust" clinical efficacy, along with being safe and well tolerated.[4][6] It has also completed a phase III clinical trial for uremic pruritus in hemodialysis patients.[9]


  1. ^ Janecka A, Perlikowska R, Gach K, Wyrebska A, Fichna J (2010). "Development of opioid peptide analogs for pain relief". Curr. Pharm. Des. 16 (9): 1126–35. doi:10.2174/138161210790963869. PMID 20030621.
  2. ^ a b "Korsuva- difelikefalin injection, solution". DailyMed. Retrieved 12 September 2021.
  3. ^ a b c d e f g h i j Raymond S. Sinatra; Jonathan S. Jahr; J. Michael Watkins-Pitchford (14 October 2010). The Essence of Analgesia and Analgesics. Cambridge University Press. pp. 490–491. ISBN 978-1-139-49198-3.
  4. ^ a b c d e Jeffrey Apfelbaum (8 September 2014). Ambulatory Anesthesia, An Issue of Anesthesiology Clinics. Elsevier Health Sciences. pp. 190–. ISBN 978-0-323-29934-3.
  5. ^ a b Alan Cowan; Gil Yosipovitch (10 April 2015). Pharmacology of Itch. Springer. pp. 307–. ISBN 978-3-662-44605-8.
  6. ^ a b c d Charlotte Allerton (2013). Pain Therapeutics: Current and Future Treatment Paradigms. Royal Society of Chemistry. pp. 56–. ISBN 978-1-84973-645-9.
  7. ^ "Korsuva: FDA-Approved Drugs". U.S. Food and Drug Administration. Retrieved 24 August 2021.
  8. ^ "Vifor Pharma and Cara Therapeutics announce U.S. FDA approval of Korsuva injection for the treatment of moderate-to-severe pruritus in hemodialysis patients" (Press release). Vifor Pharma. 24 August 2021. Retrieved 24 August 2021 – via Business Wire.
  9. ^ Fishbane S, Jamal A, Munera C, Wen W, Menzaghi F (2020). "A phase 3 trial of difelikefalin in hemodialysis patients with pruritus". N Engl J Med. 382 (3): 222–232. doi:10.1056/NEJMoa1912770. PMID 31702883.

External links[edit]

  • "Difelikefalin". Drug Information Portal. U.S. National Library of Medicine.
  • Clinical trial number NCT03422653 for "A Study to Evaluate the Safety and Efficacy of CR845 in Hemodialysis Patients With Moderate-to-Severe Pruritus (KALM-1)" at ClinicalTrials.gov
  • Clinical trial number NCT03636269 for "CR845-CLIN3103: A Global Study to Evaluate the Safety and Efficacy of CR845 in Hemodialysis Patients With Moderate-to-Severe Pruritus (KALM-2)" at ClinicalTrials.gov