AR-A 2

AR-A 2 (AR-A000002) is a selective 5-HT _1B receptor antagonist, with high affinity to guinea pig cortex 5HT _1B/1D and recombinant guinea pig 5-HT _1B receptors (K _i =0.24 and 0.47 nM) and with 10-fold lower affinity to guinea pig 5-HT _1D receptors (K _i , 5 nM), and shows an EC ₅₀ of 4.5 nM for the guinea pig 5-HT _1B receptor. AR-A 2 also binds to the rat cortical 5HT _1B/1D receptor (K _i , 20 nM), rat cortex 5-HT _2A receptor (K _i , 339 nM), rat hippocampus 5-HT _1A receptor (K _i , 3070 nM). In addition, AR-A 2 also exhibits affinity for dopamine D2 (K _i , 330 nM) and α1-adrenoceptors (K _i , 490 nM).