(R)-SKF-83959 (MCL 202) is enantiomer of D1 receptor agonist SKF-83959. (R)-SKF-83959 is reported to be a functionally selective dopamine D1 and D5 receptors ligand with much lower affinity to dopamine D2 and D3 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. Pretreatment with the selective D1- like receptor antagonist SCH 39166 dose-dependently antagonized increases in eye blinking produced by (R)-SKF-83959, confirming the involvement of D1 mechanisms in its effects.

(+)-Rotigotine is the inactive enantiomer of dopamine receptor agonist (-)-Rotigotine. (+)-Rotigotine is weak agonist of dopamine receptor.

GR 103691 is an effective and selective receptor antagonist of the D3DR (dopamine D3 receptor). GR 103691 was shown to have 100-fold higher selectivity for D3DR (dopamine D3 receptor) over the D2DR (dopamine D2 receptor) and D4DR (dopamine D4 receptor) sites. GR 103,691 is functionally active in vivo and will inhibit the hyperactivity response induced by intra-VTA (ventral tegmental area) injection of muscimol in rats.

DL-Tetrahydropalmatine (dl-THP), an active component isolated from Corydalis species (a Chinese herbal medicine). dl-THP has inhibitory effects on liver injury induced by carbon tetrachloride in mice. The drug demonstrated anxiolytic and anti-nociceptive effects in animal models. dl-THP may act through inhibition of amygdaloid dopamine release to inhibit an epileptic attack – it is a very effective anti-epileptogenic and anticonvulsant agent. dl-THP has been found to have antihypertensive effects. It acts through the 5-HT2 and/or D2-receptor antagonism in the hypothalamus to induce hypotension and bradycardia in rats.