High affinity D2 receptor agonist (EC50 values are between 17 and 75 nM in cell-based assays). Originally reported to exhibit >200-fold selectivity for the D2 receptor versus other dopamine receptor subtypes (Ki values are 9.0, 1940, >2190 and >7140 for D2, D3, D4 and D1 receptors respectively). More recently reported to be around 32-fold selective for D2 over D3 receptors (Ki values are 17.1 and 546 nM respectively). Exhibits antiParkinsonian activity. Purity 98%. MW (observed): 319.31