Potent somatostatin receptor 1 (sst1) agonist; displays selectivity for sst1 (IC50 values are 30.9 nM, 345 nM, > 1 μM, > 10 μM and > 10μM for human sst1, sst3, sst4, sst2 and sst5 respectively). Attenuates somatostatin release in the rat nucleus accumbens
AR-A 2 is a selective 5-HT1B receptor antagonist, with a high affinity to guinea pig cortex 5HT1B 1D and recombinant guinea pig 5-HT1B receptors (Ki: 0.24 and 0.47 nM) and with 10-fold lower affinity to guinea pig 5-HT1D receptor (Ki: 5 nM).