EPPTB (RO-5212773) is a drug developed by Hoffmann-La Roche which acts as a potent and selective antagonist for the trace amine-associated receptor 1, with no significant activity at other targets. EPPTB is one of the first selective antagonists developed for TAAR1, and has been used to demonstrate an important role for TAAR1 in regulation of dopaminergic signalling in the limbic system. Unfortunately while EPPTB has high affinity for the mouse TAAR1, it has much lower affinity for rat and human TAAR1, which limits its use in research. While the human and mouse forms of TAAR1 have similar functions and bind similar ligands, the actual binding affinities of individual ligands often vary significantly between the two versions of the receptor.
^Bradaia A, Trube G, Stalder H, Norcross RD, Ozmen L, Wettstein JG, Pinard A, Buchy D, Gassmann M, Hoener MC, Bettler B. The selective antagonist EPPTB reveals TAAR1-mediated regulatory mechanisms in dopaminergic neurons of the mesolimbic system. Proceedings of the National Academy of Sciences USA. 2009 Nov 24;106(47):20081-6. PMID 19892733
^Stalder H, Hoener MC, Norcross RD. Selective antagonists of mouse trace amine-associated receptor 1 (mTAAR1): discovery of EPPTB (RO5212773). Bioorganic and Medicinal Chemistry Letters. 2011 Feb 15;21(4):1227-31. PMID 21237643
^Hu LA, Zhou T, Ahn J, Wang S, Zhou J, Hu Y, Liu Q. Human and mouse trace amine-associated receptor 1 have distinct pharmacology towards endogenous monoamines and imidazoline receptor ligands. Biochemical Journal. 2009 Oct 23;424(1):39-45. PMID 19725810