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).
L-690330 is a competitive inositol monophosphatase inhibitor (Kis: 0.27 and 0.19 μM for recombinant human and bovine IMPase, 0.30 and 0.42 μM for human and bovine frontal cortex IMPase). L-690330 shows 10-fold more sensitive than a mouse and rat IMPase.