Setipiprant (INN) (developmental code names ACT-129,968, KYTH-105) is a drug originally developed by Actelion which acts as a selective, orally available antagonist of the prostaglandin D2 receptor 2 (DP2). It was initially researched as a treatment for allergies and inflammatory disorders, particularly asthma, but despite being well tolerated in clinical trials and showing reasonable efficacy against allergen-induced airway responses in asthmatic patients, it failed to show sufficient advantages over existing drugs and was discontinued from further development in this application.