3, 4-dihydroxyphenylacetic acid (DOPAC) is a neuronal metabolite of dopamine (DA). DA undergoes monoamine oxidase-catalyzed oxidative deamination to 3,4-dihydroxyphenylacetaldehyde (DOPAL), which is metabolized primarily to 3,4-dihydroxyphenylacetic acid (DOPAC) via aldehyde dehydrogenase, ALDH2. DOPAC exhibits the antiproliferative effect in colon cancer cells. In addition, DOPAC enhances not only the total ALDH activity but also the gene expression of ALDH1A1, ALDH2, and ALDH3A1 in a concentration-dependent manner. The pretreatment of DOPAC completely protects the cells from the acetaldehyde-induced cytotoxicity, thus DOPAC acts as a potential ALDH inducer to prevent the alcohol-induced abnormal reaction.

Raclopride is a salicylamide neuroleptic, that acts as a selective antagonist of D2 dopamine receptors both in vitro and in vivo. Tritium-labelled raclopride has properties that demonstrate its usefulness as a radioligand for the labelling of dopamine-D2 receptors : 3H-Raclopride has a high affinity for the rat and human dopamine-D2 receptors, the non-specific binding of 3H-raclopride is very low, not exceeding 5% of the total binding and the distribution of the 3H-raclopride binding sites in the brain closely correlates with the dopaminergic innervation. The binding of 3H-raclopride is blocked by dopamine-D2 agonists and antagonists, while the D1 agonist SKF 38393 and the Dl antagonist SCH 23390 have much less potency. The interaction of dopamine with 3H-raclopride binding results in a shallow competition curve, which suggests that 3H-raclopride, similar to other dopamine-D2 radioligands, labels both high and low agonist affinity states of the dopamine-D2 receptor. The in vivo receptor binding studies performed with 3H-raclopride also demonstrate its favorable properties as a dopamine-D2 receptor marker in vivo In contrast to some other compounds used as radioligands, raclopride enters the brain readily and binds with a low component of non-specific binding in all dopamine-rich brain areas. A saturation curve may be achieved in vivo binding studies since injections of increasing concentrations of 3H-raclopride appears to be saturated at concentrations above 25 mkCi (corresponding to approximately 5 nmol/kg). Raclopride antagonizes apomorphine-induced hyperactivity in the rat at low doses (ED50 = 130 nM/kg i.p.) but induces catalepsy only at much higher doses (ED50 = 27 mkM/kg i.p.). Radiolabelled raclopride has been used as a ligand for in vitro and in vivo autoradiography in rat and primate brains. Raclopride C 11 is used with positron emission tomography (PET) as a clinical research tool to determine dopamine type 2 (D 2) receptor density in the human brain under normal and pathological conditions. For example, raclopride C 11 used in PET studies has served to confirm the age-related decrease in striatal dopamine D2 receptor density, which may be associated with a decline in the motor as well as cognitive functions. In patients with Alzheimer's disease, raclopride C 11 may be used to examine neuroreceptor distribution and quantities, which may help in the analysis of degenerative alterations of neuron populations and neuroreceptor systems in patients with this disease. In Huntington's disease, in which degeneration of neostriatal interneurons occurs (postsynaptic to the dopaminergic input), specific binding of raclopride C 11 to D 2 receptors may serve as one of the parameters in predicting performance in cognitive tasks.

Terguride (INN), also known as trans-dihydrolisuride, is a serotonin receptor antagonist and dopamine receptor agonist of the ergoline family. Terguride is approved for and used in the treatment of hyperprolactinemia. Terguride is an oral, potent antagonist of 5-HT2B and 5-HT2A (serotonin) receptors. Serotonin stimulates the proliferation of pulmonary artery smooth muscle cells and induces fibrosis in the wall of pulmonary arteries. Together, this causes vascular remodeling and narrowing of the pulmonary arteries. These changes result in increased vascular resistance and PAH. Due to the potential anti-proliferative and anti-fibrotic activity of terguride, this potential medicine could offer the hope of achieving reversal of pulmonary artery vascular remodeling and attenuation of disease progression. In May 2008, terguride was granted orphan drug status for the treatment of pulmonary arterial hypertension. In May 2010 Pfizer purchased worldwide rights for the drug.

Docarpamine (marketed under the tradename Tanadopa) is a dopamine prodrug developed in Japan for the treatment of chronic heart failure. The drug does not cross the blood-brain barrier and shows no effect on CNS activity. It is supposed that the drug exerts its action by activating dopamine receptor D1.