RS-127445 is a drug which acts as a potent and selective antagonist at the serotonin5-HT2Breceptor, with around 1000x selectivity over the closely related 5-HT2A and 5-HT2C receptors. The role of the 5-HT2B receptor in the body is still poorly understood, and RS-127445 has been a useful tool in unravelling the function of the various systems in which this receptor is expressed.
^Kelly CR, Sharif NA (June 2006). "Pharmacological evidence for a functional serotonin-2B receptor in a human uterine smooth muscle cell line". The Journal of Pharmacology and Experimental Therapeutics. 317 (3): 1254–61. doi:10.1124/jpet.105.100172. PMID16517693. S2CID6604193.