WAY-100635 is an achiral phenylpiperazine derivative that originally discovered as an antagotist of 5-HT1A receptor. Later WAY-100635 was described as a potent dopamine D4 receptor agonist. WAY-100635 was in preclinical studies for the treatment of Diabetes mellitus, Anxiety and Cognition disorders, howevere the development was discontinued. Isotope labeled WAY-100635 could be used for the study of central 5-HT 1A receptors with potential for application to the study of neuropsychiatric disorders and to the human pharmacology of psychoactive drugs.

3-Tyrosine, in contrast to the para isomer, is readily racemized. The majority of the load was metabolized to m-hydroxyphenylacetic acid but m-hydroxymandelic acid and 3,4-dihydroxyphenylacetic acid were also detected. Low circulating levels of m-tyrosine in the plasma suggest that most of the load is held due to a first pass effect somewhere in the enterohepatic system and that this portion of the load is not in equilibrium with the plasma m-tyrosine. The metabolism of a m-tyrosine may give further insight into the deficiencies of the phenylalanine hydroxylating system found in the various phenotypes of phenylketonuria. 3-Tyrosine has been used experimentally as a substitute for L-DOPA in the treatment of Parkinsonism. 3-tyrosine mimics the action of Dopa in two experimental animal models. It was also obvious from the experiments with d,l- and l-m-tyrosine that only the l-isomer (3-Tyrosine) is active.

Sodium 2-Mercaptobenzothiazole (sodium MBT) is utilized as a corrosion inhibitor and fungicide. By analogy to MBT, sodium MBT is identified as a skin sensitizer. Sodium 2-Mercaptobenzothiazole is also used to make rubber accelerators, as a preservative for latex paint and wood, a metal chelator, and a thermal stabilizer (methyl methacrylate copolymers, acrylonitrile polymers, polyester fibers, anion exchange resins, polyoxyphenylene, and silicon fluids), also used in electroplating (silver, nickel, and cobalt), to separate sulfide ore from copper ore, for dyeing textiles, in transmission fluids, and to prevent discoloration of freeze dried bananas; uses of 50% aqueous solution include as a corrosion inhibitor for nonferrous metals in antifreeze and coolants and in paper mill systems; used as a biocide in metalworking fluids and paper manufacturing.

Subitramine is a potent inhibitor of monoamines (serotonin, dopamine, noradrenaline) reuptake that was approved by FDA for the treatmen of obesity. Sibutramine is metabolized to metabolites M1 and M2 which are more active toward the monoamine transporters.The drug was withdrawn from the market because of clinical trial data indicating an increased risk of heart attack and stroke. It was sold under a variety of brand names including Reductil, Meridia and Sibutrex.

Fenoldopam (marketed under the brand name Corlopam) is a drug and synthetic benzazepine derivative which acts as a selective D1 receptor partial agonist. Fenoldopam is a rapid-acting vasodilator. It is an agonist for D1-like dopamine receptors and binds with moderate affinity to α2-adrenoceptors. It has no significant affinity for D2-like receptors, α1 and β adrenoceptors, 5HT1 and 5HT2 receptors, or muscarinic receptors. Fenoldopam is a racemic mixture with the R-isomer responsible for the biological activity. The R-isomer has approximately 250-fold higher affinity for D1-like receptors than does the S-isomer. Fenoldopam Mesylate Injection, USP is indicated for the in-hospital, short-term (up to 48 hours) management of severe hypertension when rapid, but quickly reversible, emergency reduction of blood pressure is clinically indicated, including malignant hypertension with deteriorating end-organ function.

Pergolide is a long-acting dopamine agonist approved in 1982 for the treatment of Parkinson’s Disease. It is an ergot derivative that acts on the dopamine D2 and D3, alpha2- and alpha1-adrenergic, and 5-hydroxytryptamine (5-HT) receptors. It was indicated as adjunct therapy with levodopa/carbidopa in the symptomatic treatment of parkinsonian syndrome. It was later found that pergolide increased the risk of cardiac valvulopathy. The drug was withdrawn from the US market in March 2007 and from the Canadian market in August 2007. Pergolide stimulates centrally-located dopaminergic receptors resulting in a number of pharmacologic effects. Five dopamine receptor types from two dopaminergic subfamilies have been identified. The dopaminergic D1 receptor subfamily consists of D1 and D5 subreceptors and are associated with dyskinesias. The dopaminergic D2 receptor subfamily consists of D2, D3 and D4 subreceptors and has been associated with improvement of symptoms of movement disorders. Thus, agonist activity specific for D2 subfamily receptors, primarily D2 and D3 receptor subtypes, are the primary targets of dopaminergic antiparkinsonian agents. It is thought that postsynaptic D2 stimulation is primarily responsible for the antiparkinsonian effect of dopamine agonists, while presynaptic D2 stimulation confers neuroprotective effects. This semisynthetic ergot derivative exhibits potent agonist activity on dopamine D2- and D3-receptors. It also exhibits agonist activity on dopamine D4, D1, and D5, 5-hydroxytryptamine (5-HT)1A, 5-HT1B, 5-HT1D, 5-HT2A, 5-HT2B, 5-HT2C, α2A-, α2B-, α2C-, α1A-, α1B-, and α1D-adrenergic receptors. Parkinsonian Syndrome manifests when approximately 80% of dopaminergic activity in the nigrostriatal pathway of the brain is lost. As this striatum is involved in modulating the intensity of coordinated muscle activity (e.g. movement, balance, walking), loss of activity may result in dystonia (acute muscle contraction), Parkinsonism (including symptoms of bradykinesia, tremor, rigidity, and flattened affect), akathesia (inner restlessness), tardive dyskinesia (involuntary muscle movements usually associated with long-term loss of dopaminergic activity), and neuroleptic malignant syndrome, which manifests when complete blockage of nigrostriatal dopamine occurs. High dopaminergic activity in the mesolimbic pathway of the brain causes hallucinations and delusions; these side effects of dopamine agonists are manifestations seen in patients with schizophrenia who have overractivity in this area of the brain. The hallucinogenic side effects of dopamine agonists may also be due to 5-HT2A agonism. The tuberoinfundibular pathway of the brain originates in the hypothalamus and terminates in the pituitary gland. In this pathway, dopamine inhibits lactotrophs in anterior pituitary from secreting prolactin. Increased dopaminergic activity in the tuberoinfundibular pathway inhibits prolactin secretion. Pergolide also causes transient increases in somatotropin (growth hormone) secretion and decreases in luteinizing hormone (LH) concentrations. Pergolide is not available for use by humans in the United States, but approved for veterinary use; it was used in various other countries for the treatment of various conditions including Parkinson's disease, hyperprolactinemia, and restless leg syndrome. Pergolide in Europe was indicated for Parkinson's disease only when other dopaminergic agonist treatments had failed, and treatment had to be initiated by a neurologist. The label warned against using doses of more than 5mg a day, whether alone or in combination with levodopa. However the marketing of this drug finally stopped in France in May 2011 and sales elsewhere in Europe ceased eventually.

Nomifensine was developed by Hoechst AG as a potent inhibitor of noradrenaline, dopamine, and 5-HT uptake displayed antidepressant activity. It was first marketed in the UK in 1977 for the treatment of depression. Between 1977 and 1982 there were reports of hemolytic anemia in association with the drug, and this suspected adverse reaction was included in the 1981 edition of the data Sheet Compendium. FDA published a notice of its determination that Merital capsules were removed from the market for safety reasons.

Benzquinamide also known as BZQ; Emete-con, Emetico, is an antiemetic drug, which was discontinued. That drug was used to prevent and treat nausea and vomiting associated with anesthesia and surgery, administered intramuscularly or intravenously. The mechanism of action is not known, but was made predictions which shown, that in spite of benzquinamide did bind to the α2A, α2B, and α2C adrenergic receptors (α2-AR). It was known, that this activity may partially explain the anxiolytic activity effect of the drug. But the dopamine D2 receptor, which by ligand-set similarity resembles α2-AR is an accepted target for emesis. Then benzquinamide was tested towards to the D2, D3, and D4 receptors. Notwithstanding the fact that the α2-AR values are lower than the D2 values, it was predicted, that D2 activity may be the most relevant for emesis.

Phenylalanine is a biologically essential amino acid that acts as a precursor to tyrosine and the catecholamines (epinephrine, norepinephrine, dopamine, and tyramine), and is a constituent of many central nervous system neuropeptides. Normal dietary levels of phenylalanine are approximately 1-2 grams daily. Phenylalanine appears in two forms which are identical mirror images of each other: L-phenylalanine, a nutritional supplement, and D-phenylalanine, an effective painkiller and antidepressant due to its ability to inhibit the breakdown of enkephalins, the brain’s natural pain killers.

Mesoridazine (brand name Serentil) is a phenothiazine antipsychotic. It was marketed in the U.S. for the treatment of schizophrenia, behavioral problems in mental deficiency and chronic brain syndrome, alcoholism and psychoneurotic symptoms, such as anxiety and tension. Due to the risk of serious cardiac events the indicated use of Serentil was limited to severely ill schizophrenic patients who fail other therapies. Based upon animal studies, mesoridazine acts indirectly on reticular formation, whereby neuronal activity into reticular formation is reduced without affecting its intrinsic ability to activate the cerebral cortex. Mesoridazine shows a moderate adrenergic blocking activity in vitro and in vivo and antagonizes 5-hydroxytryptamine in vivo.