Difelikefalin (Korsuva™) is a synthetic peptide agonist of the kappa opioid receptor being developed by Cara Therapeutics for the treatment of pruritus. In August 2021, intravenous difelikefalin was approved in the USA for the treatment of moderate-to-severe pruritus associated with chronic kidney disease (CKD) in adults undergoing haemodialysis. Difelikefalin selectively acts on kappa opioid receptors in peripheral tissues, which contribute to pruritis and nociception. The activation of opioid receptors in peripheral neurons and keratinocytes reduces afferent (sensory) impulses towards the central nervous system, decreasing pain signals. Activating kappa opioid receptors on immune cells, including monocytes and T lymphocytes, decreases the release of pro-inflammatory chemicals such as prostaglandins.

Obeticholic acid (also known as INT-747), is a potent, orally bioavailable farnesoid X receptor (FXR) agonist. The key role of the farnesoid X receptor (FXR) as a regulator of bile and cholesterol metabolism in the liver, with preclinical data from numerous studies providing strong rationale for the advancement of FXR agonists as hepatoprotective therapeutics in chronic liver disease. Obeticholic acid is marketed under the trade name Ocaliva. Ocaliva is specifically indicated for the treatment of primary biliary cholangitis (PBC) in combination with ursodeoxycholic acid (UDCA) in adults with an inadequate response to UDCA, or as monotherapy in adults unable to tolerate UDCA.

Cholic acid is a primary bile acid synthesized from cholesterol in the liver. Endogenous bile acids including cholic acid enhance bile flow and provide the physiologic feedback inhibition of bile acid synthesis. The mechanism of action of cholic acid has not been fully established; however, it is known that cholic acid and its conjugates are endogenous ligands of the nuclear receptor, farnesoid X receptor (FXR). FXR regulates enzymes and transporters that are involved in bile acid synthesis and in the enterohepatic circulation to maintain bile acid homeostasis under normal physiologic conditions. U.S. Food and Drug Administration approved Cholbam (cholic acid) capsules, the first FDA approved treatment for pediatric and adult patients with bile acid synthesis disorders due to single enzyme defects, and for patients with peroxisomal disorders (including Zellweger spectrum disorders).

Difelikefalin (Korsuva™) is a synthetic peptide agonist of the kappa opioid receptor being developed by Cara Therapeutics for the treatment of pruritus. In August 2021, intravenous difelikefalin was approved in the USA for the treatment of moderate-to-severe pruritus associated with chronic kidney disease (CKD) in adults undergoing haemodialysis. Difelikefalin selectively acts on kappa opioid receptors in peripheral tissues, which contribute to pruritis and nociception. The activation of opioid receptors in peripheral neurons and keratinocytes reduces afferent (sensory) impulses towards the central nervous system, decreasing pain signals. Activating kappa opioid receptors on immune cells, including monocytes and T lymphocytes, decreases the release of pro-inflammatory chemicals such as prostaglandins.

Cholic acid is a primary bile acid synthesized from cholesterol in the liver. Endogenous bile acids including cholic acid enhance bile flow and provide the physiologic feedback inhibition of bile acid synthesis. The mechanism of action of cholic acid has not been fully established; however, it is known that cholic acid and its conjugates are endogenous ligands of the nuclear receptor, farnesoid X receptor (FXR). FXR regulates enzymes and transporters that are involved in bile acid synthesis and in the enterohepatic circulation to maintain bile acid homeostasis under normal physiologic conditions. U.S. Food and Drug Administration approved Cholbam (cholic acid) capsules, the first FDA approved treatment for pediatric and adult patients with bile acid synthesis disorders due to single enzyme defects, and for patients with peroxisomal disorders (including Zellweger spectrum disorders).