Budipine is an antiparkinsonian drug, which was developed by Byk Gulden (now Takeda) for the treatment of Parkinson's disease. The drug has multiple mechanisms of action: it was found to interfere with dopamine biosynthesis, mainly by inhibiting MAO-B enzyme and stimulating aromatic L-amino acid decarboxylase. Also the drug inhibits the dopamine re-uptake and has weak affinity to NMDA and muscarinic receptors. Budipine passes the blood-brain barrier, is metabolized by hydroxylation, and is excreted by both in urine and feces within 24 h.

Remoxipride is a substituted benzamide. It is a weak, but relatively selective, central dopamine D2-receptor antagonist and appears to have preferential affinity for extrastriatal dopamine D2-receptors. It also has marked affinity for central sigma receptors. It was introduced by Astra (Roxiam) at the end of the eighties and was prescribed as an atypical antipsychotic. Remoxipride was withdrawn from the market worldwide by Astra because of several cases of aplastic anaemia associated with the drug.

Fencamfamin is a camphane derivative, although lacking typical sympathomimetic properties. It is structurally related to the phenylethylamines. It is a central nervous stimulant with pharmacological properties similar to amphetamine. Fencamfamin developed primarily as appetite suppressant or pscyhostimulant, not to increase awareness. Fencamfamin reduces REM sleep and prevents fatigue in subjects deprived of sleep. Fencamfamin raises a mood.

Clebopride is a dopamine antagonist drug. It is used to treat functional gastrointestinal disorder such as nausea or vomiting. Unchanged parent drug was the most abundant compound in human urine. Major metabolites included the hydroxylation at benzyl group to yield carbinolamine and its further N-dealkylation product, and the piperidine ring hydroxylation/oxidation metabolite (a lactam).

Itopride is a dopamine D2 receptor antagonist and inhibitor of acetylcholinesterase. It is indicated in the for the treatment of gastrointestinal symptoms caused by reduced gastrointestinal motility, such as functional non-ulcer dyspepsia (chronic gastritis), gastric fullness, rapid satiation, pain or discomfort in the upper abdomen, anorexia, heartburn, nausea, and vomiting. The drug is not approved in the USA or UK but is available in Japan and Western European countries.

Minaprine, a psychotropic drug, which was effective in the treatment of various depressive states. This drug was withdrawn because of the serious side effect. It was found, that minaprine inhibited the following enzymes, acetylcholinesterase and monoamine oxidase (MOA) A. It also binds to dopamine D1 and D2 receptors. Experiments on rodents also have revealed that minaprine suppressed the inhibitory effect of hydroxytryptamine (5-HT) on dopamine (DA) release via the inhibition of 5-HT binding at the 5-HT2 receptor on the nerve terminal.

Piribedil is an antiparkinsonian agent which acts as D2 and D3 receptor agonist. In European countries and worldwide it is used as a monotherapy or in combination with dopatherapy for treatment of Parkinson's disease, cognitive impairment and obliterating arteriopathy.

Guanoclor is an anti-hypertensive agent developed by Pfizer Ltd. (U.K.). It seems to be effective in various types of hypertension (unknown aetiology, renal, and malignant). It affects both systolic blood-pressure and diastolic blood-pressure. It is an adrenergic neurone-blocking agent, which also interferes with noradrenaline synthesis by inhibition of the enzyme dopamine beta-hydroxylase. Clinical use of the compound was first reported by Lawrie et al. (1964), who achieved satisfactory blood-pressure control in 60% of their cases with guanoclor alone, and in a further 18% with the addition of a thiazide diuretic. They also noted a significant reduction in urinary noradrenaline levels during guanoclor administration. Guanochlor has an affinity for the Na+/H+ exchanger ranging between 0.5 uM and 6 uM in different systems and is more potent than amiloride in all systems studied. It is suggested that guanochlor recognizes a binding site on the Na+/H+ exchanger that is distinct from the amiloride binding site.

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.

Nefopam (nefopam hydrochloride) is a potent, rapidly-acting non-narcotic analgesic. It is totally distinct from other centrally-acting analgesics such as morphine, codeine, pentazocine and propoxyphene. Unlike the narcotic agents, nefopam (nefopam hydrochloride) has been shown not to cause respiratory depression. It is indicated for the relief of acute and chronic pain, including post-operative pain, dental pain, musculo-skeletal pain, acute traumatic pain and cancer pain. Its mechanism of action is unclear.