SCH-50971 is a histamine H<sub>3</sub> receptor agonist which was under development for the treatment of anxiety disorders, gastrointestinal disorders, and migraine but was never marketed.
The drug acts as a potent, selective, and high-affinity agonist of the histamine H<sub>3</sub> receptor. It has negligible affinity for the histamine H<sub>1</sub> receptor and other assessed receptors. The drug is also not a histamine H<sub>2</sub> receptor antagonist. It has greatly improved selectivity compared to the earlier selective histamine H<sub>3</sub> receptor agonist (R)-ñ-methylhistamine. The drug is orally active and shows anti-allergy effects, antimigraine effects, sedative and hypnotic effects, and hypolocomotion in animals. In terms of chemical structure, it is a cyclized pyrrolidine derivative of histamine.
SCH-50971 was under development by Schering-Plough. It reached the discovery or preclinical research stage of development. The development of the drug was discontinued by 2001. SCH-50971 was first described in the scientific literature by 1994.