BP-897 is a dopamine D3 receptor partial agonist. It selectively binds to the dopamine D3 over the D2, D1, and D4 receptors (Kis = 0.92, 61, 3,000, and 300 nM, respectively, for the recombinant human receptors). It is also selective over α1- and α2-adrenergic receptors (Kis = 60 and 83 nM, respectively) and the serotonin (5-HT) receptor subtypes 5-HT1A and 5-HT7 (Kis = 84 and 345 nM, respectively), as well as muscarinic, histamine, and opioid receptors (Kis = >1 μM for all). BP-897 inhibits cAMP accumulation induced by forskolin (EC50 = 1 nM) and increases mitogenesis in NG 108-15 cells with a maximum efficacy of 55%, an effect that can be blocked by the dopamine D3 receptor antagonist nafadotride. It also acts as a dopamine D3 receptor antagonist, failing to increase [35S]GTPγS binding to CHO cell membranes expressing the recombinant human D3 receptor and inhibiting the effect of dopamine in the same assay (IC50 = 416.87 nM). BP-897 (0.5 and 1 mg/kg) reduces cocaine-seeking behavior, but has no reinforcing properties itself, in rats trained to self-administer cocaine.
