Propylnorapomorphine is a potent and selective D2 receptor agonist. Propylnorapomorphine is used as a tool compound to label dopamine receptors in rodent brain, and elicits dopaminergic behavioural effects. It stimulates motor activity, induces stereotypic behaviour and sexual stimulation. Propylnorapomorphine was investigated in clinical trial against Parkinson's disease and schizophrenia

N-Methylspiperone (NMSP) is a derivate of spiperone and high-affinity D2/3 dopamine and 5-HT2A serotonin receptor antagonist. In the biodistribution studies in rodents, there was a high accumulation of radioactivity in the liver, lung, and kidneys, whereas the brain radioactivity was not as high N-Methylspiperone is used to study the dopamine and serotonin neurotransmitter systems. Labeled with the radioisotope carbon-11, it can be used for positron emission tomography (PET). [11C] N-Methylspiperone PET is useful for objective monitoring of D2and 5-HT2A receptor occupancy and density in patients being treated with antipsychotic drugs.

(S)-SKF-83959 (MCL 201) is enantiomer of D1 receptor agonist SKF-83959. (S)-SKF-83959 is reported to be a functionally selective dopamine D1 receptor ligand with much lower affinity to dopamine D2, D3 and D5 receptors. (R)-SKF-83959 like SKF-83959, produced dose related effects on overt behavior (eye blinking) and schedule-controlled performance in squirrel monkeys. (R)-SKF-83959 increases in eye blinking and decreases in rates of fixed-ratio responding. In contrast to the effects of its S-(-) enantiomer, was relatively devoid of behavioral activity up to doses that were approximately 10-fold greater than (R)-SKF-83959.