Ecopipam (SCH 39166) hydrochloride is a highly potent, selective, and orally active antagonist of dopamine D1 D5 receptors. It exhibits impressive binding affinities, with Ki values of 1.2 nM and 2.0 nM for D1 and D5 receptors, respectively. Ecopipam hydrochloride demonstrates remarkable selectivity, displaying over 40-fold selectivity compared to D2, D4, 5-HT, and α2a receptors, with Ki values of 0.98 μM, 5.52 μM, 0.08 μM, and 0.73 μM, respectively. Its application extends to various areas of research, including schizophrenia, cocaine addiction, and obesity [1] [3].