Pramipexole is a nonergot dopamine agonist with high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors, binding with higher affinity to D3 than to D2 or D4 receptor subtypes. The relevance of D3 receptor binding in Parkinson's disease is unknown. The precise mechanism of action of Pramipexole as a treatment for Parkinson's disease is unknown, although it is believed to be related to its ability to stimulate dopamine receptors in the striatum. This conclusion is supported by electrophysiologic studies in animals that have demonstrated that Pramipexole influences striatal neuronal firing rates via activation of dopamine receptors in the striatum and the substantia nigra, the site of neurons that send projections to the striatum. Pramipexole is used for the treatment of signs and symptoms of idiopathic Parkinson's disease.

Bromocriptine is an ergot derivative with potent dopamine receptor agonist activity, which activates post-synaptic dopamine receptors. Bromocriptine is indicated for the treatment of dysfunctions associated with hyperprolactinemia. Bromocriptine therapy is indicated in the treatment of acromegaly and in the treatment of the signs and symptoms of idiopathic or postencephalitic Parkinson’s disease. It is approved as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. Some commonly reported adverse reactions include nausea, fatigue, dizziness, vomiting and headache. Bromocriptine may interact with dopamine antagonists, butyrophenones and certain other agents.

Trifluoperazine (Eskazinyl, Eskazine, Jatroneural, Modalina, Stelazine, Terfluzine, Trifluoperaz, Triftazin) is a typical antipsychotic of the phenothiazine chemical class used for the short-term treatment of certain types of anxiety. Trifluoperazine blocks postsynaptic mesolimbic dopaminergic D1 and D2 receptors in the brain; depresses the release of hypothalamic and hypophyseal hormones and is believed to depress the reticular activating system thus affecting basal metabolism, body temperature, wakefulness, vasomotor tone, and emesis. The primary application of trifluoperazine is for schizophrenia. Other official indications may vary country by country, but generally, it is also indicated for use in agitation and patients with behavioral problems, severe nausea, and vomiting as well as severe anxiety. Trials have shown a moderate benefit of this drug in patients with borderline personality disorder. A 2004 meta-analysis of the studies on trifluoperazine found that it is more likely than placebo to cause extrapyramidal side effects such as akathisia, dystonia, and Parkinsonism. It is also more likely to cause somnolence and anticholinergic side effects such as red-eye and xerostomia (dry mouth).

Trifluoperazine (Eskazinyl, Eskazine, Jatroneural, Modalina, Stelazine, Terfluzine, Trifluoperaz, Triftazin) is a typical antipsychotic of the phenothiazine chemical class used for the short-term treatment of certain types of anxiety. Trifluoperazine blocks postsynaptic mesolimbic dopaminergic D1 and D2 receptors in the brain; depresses the release of hypothalamic and hypophyseal hormones and is believed to depress the reticular activating system thus affecting basal metabolism, body temperature, wakefulness, vasomotor tone, and emesis. The primary application of trifluoperazine is for schizophrenia. Other official indications may vary country by country, but generally, it is also indicated for use in agitation and patients with behavioral problems, severe nausea, and vomiting as well as severe anxiety. Trials have shown a moderate benefit of this drug in patients with borderline personality disorder. A 2004 meta-analysis of the studies on trifluoperazine found that it is more likely than placebo to cause extrapyramidal side effects such as akathisia, dystonia, and Parkinsonism. It is also more likely to cause somnolence and anticholinergic side effects such as red-eye and xerostomia (dry mouth).

Tetrahydropalmatine is a tetrahydroprotoberberine isoquinoline alkaloid that is a primary active constituent of herbal preparations containing plant species of the genera Stephania and Corydalis. The levo isomer of THP (L-THP) appears to contribute to many of the therapeutic effects of these preparations. The pharmacological profile of L-THP, which includes antagonism of dopamine D1 and D2 receptors and actions at dopamine D3, suggests that it may have utility for treating addiction. Clinical trials where L-THP was used for the treatment of cocaine and heroin addiction have promising results. The clinical trial is planned for the treatment of schizophrenia. L-Tetrahydropalmatine is recorded in the Chinese pharmacopoeia.

Sumanirole is a novel dopamine agonist with high affinity and efficacy at D2 dopamine receptors and has a substantial degree of selectivity for the D2 receptor over other dopamine receptor subtypes. It had been in clinical trials for the treatment of Parkinson’s disease and restless leg syndrome but these studies were terminated for the efficacy reason.

Quinelorane is an octahydropyrimido[4,5-g]quinolone derivative patented by American pharmaceutical company Eli Lilly and Co. as for the treatment anxiety, Parkinson's syndrome, depression, and hypertension. Quinelorane acts as an agonist of dopamine agonist for the D2 and D3 receptors. In preclinical studies Quinelorane (IM) treatment produced dose-dependent effects on male sexual responding. Penile erections and masturbation were markedly facilitated following treatment with either 2.5 or 5 micrograms/kg quinelorane. Higher doses of quinelorane (10 and 25 micrograms/kg) generally did not further augment sexual responding but rather resulted in a return in sexual responding to control vehicle levels. Quinelorane had a biphasic effect on yawning behavior of the monkeys with low doses (2.5 and 5 micrograms/kg) facilitating yawning and high doses (25 micrograms/kg) inhibiting yawning.

Pardoprunox is a partial D2/3 dopamine receptor agonist and full 5-HT1A serotonin receptor agonist. Partial D(2/3) dopamine (DA) receptor agonists provide a novel approach to the treatment of the motor symptoms of Parkinson's disease that may avoid common dopaminergic side effects, including dyskinesia and psychosis. Pardoprunox passed phase III clinical trial for the treatment of Parkinson's disease.

Aplindore (DAB-452) is a small molecule that displays potent dopamine D2 receptor partial agonist activity in in vitro and in vivo assays and is predicted to have antipsychotic efficacy without motor side effects. Aplindore had been in phase II clinical trials for the treatment of Parkinson's disease and restless legs syndrome. Aplindore was generally well tolerated and there were no withdrawals due to adverse events and no serious adverse events.

Quinpirole (LY 171,555) is a psychoactive drug and research chemical which acts as a selective D2 and D3 receptor agonist. Quinpirole is the most widely used D2 agonist in in vivo and in vitro studies. Specific quinpirole binding in rat brain was saturable, and dependent on temperature, membrane concentration, sodium concentration and guanine nucleotides. Saturation analysis revealed high affinity binding characteristics (KD = 2.3 nM) which were confirmed by association-dissociation kinetics. The regional distribution of [3H]quinpirole binding sites roughly paralleled the distribution of [3H]spiperone binding sites, with greatest densities present in the striatum, nucleus accumbens and olfactory tubercles. A variety of drugs, most notably monoamine oxidase inhibitors (MAOls), inhibit the binding of [3H]quinpirole, but not [3H]spiperone or [3H](-)N-n-Propylnorapomorphine, in rat striatal membranes by a mechanism that does not appear to involve the enzymatic activity of MAO. Clinically antidepressant MAOIs exhibited selectivity between sites labeled by [3H]quinpirole and [3H]spiperone as did a number of structurally related propargylamines and N-acylethylenediamine derivatives and other drugs such as debrisoquin and phenylbiguanide. Quinpirole has been shown to increase locomotion and sniffing behavior in mice and induces compulsive behavior symptomatic of obsessive compulsive disorder in rats.