SCH-23390 is a potent and selective antagonist of the dopamine-1 and dopamine-5 receptors (Ki = 0.2 and 0.3 nM respectively). It was found to prevent death from d-amphetamine overdose in rats and has also been investigated as a potential treatment for Parkinson's Disease and Bipolar Disorder. A single clinical trial was conducted in healthy humans where SCH-23390 induced akathisia (motor restlessness). Preclinical and clinical trials as therapeutic have been discontinued due to side-effects and lack of efficacy. However, it should be noted that a C11 radiolabeled version of the compound has been synthesized and used as a PET imaging probe for the study of Parkinson's Disease and Huntington's Disease.