SCH-23390 hydrochloride (R-(+)-SCH-23390 hydrochloride) is a potent and selective dopamine D1-like receptor antagonist with Kis of 0.2 nM and 0.3 nM for the D1 and D5 receptor, respectively. SCH-23390 hydrochloride is a potent and high efficacy human 5-HT2C receptor agonist with a Ki of 9.3 nM. SCH-23390 hydrochloride also binds with high affinity to the 5-HT2 and 5-HT1C receptors. SCH-23390 hydrochloride inhibits G protein-coupled inwardly rectifying potassium (GIRK) channels with an IC50 of 268 nM.