Dopaminergic
D2-like receptor agonists include the ergolines bromocriptine, cabergoline, dihydroergocryptine, ergoloid, lisuride, metergoline, pergolide, quinagolide, and terguride; the morphine analogue apomorphine; and the structurally distinct agents piribedil, pramipexole, ropinirole, rotigotine, and talipexole.
They are used to treat Parkinson's disease, restless legs syndrome, hyperprolactinemia, prolactinomas, acromegaly, erectile dysfunction, and for lactation suppression.
D1-like receptor agonists include 6-Br-APB, A-68930, A-77636, A-86929, adrogolide, dihydrexidine, dinapsoline, doxanthrine, fenoldopam, razpipadon, SKF-81,297, SKF-82,958, SKF-89,145, tavapadon, and trepipam.
Dopamine releasing agents (DRAs) such as phenethylamine, amphetamine, lisdexamfetamine (Vyvanse), methamphetamine, methylenedioxymethamphetamine (MDMA), phenmetrazine, pemoline, 4-methylaminorex (4-MAR), phentermine, and benzylpiperazine, among many others, which, like DRIs, are used in the treatment of attention-deficit hyperactivity disorder (ADHD) and narcolepsy as psychostimulants, obesity as anorectics, depression and anxiety as antidepressants and anxiolytics respectively, drug addiction as anticraving agents, and sexual dysfunction as aphrodisiacs.
[17] The effects of the activity enhancers may be mediated by intracellular TAAR1 agonism coupled with uptake into monoaminergic neurons by monoamine transporters.
[18][19] Dopaminergic activity enhancers are of interest in the potential treatment of a number of medical disorders, such as depression and Parkinson's disease.
[17] Vesicular monoamine transporter 2 (VMAT2) inhibitors such as reserpine, tetrabenazine, valbenazine, and deutetrabenazine act as dopamine depleting agents and are used as sympatholytics or antihypertensives, to treat tardive dyskinesia, and in the past as antipsychotics.
Monoamine oxidase (MAO) inhibitors (MAOIs) including non-selective agents such as phenelzine, tranylcypromine, isocarboxazid, and pargyline, MAOA selective agents like moclobemide and clorgyline, and MAOB selective agents such as selegiline and rasagiline, as well as the harmala alkaloids like harmine, harmaline, tetrahydroharmine, harmalol, harman, and norharman, which are found to varying degrees in Nicotiana tabacum (tobacco), Banisteriopsis caapi (ayahuasca, yage), Peganum harmala (Harmal, Syrian Rue), Passiflora incarnata (Passion Flower), and Tribulus terrestris, among others, which are used in the treatment of depression and anxiety as antidepressants and anxiolytics, respectively, in the treatment of Parkinson's disease and dementia, and for the recreational purpose of boosting the effects of certain drugs like phenethylamine (PEA) and psychedelics like dimethyltryptamine (DMT) via inhibiting their metabolism.
Catechol O-methyl transferase (COMT) inhibitors such as entacapone, opicapone, and tolcapone, which are used in the treatment of Parkinson's disease.
[20][21][22] Aromatic L-amino acid decarboxylase (AAAD) or DOPA decarboxylase inhibitors including benserazide, carbidopa, and methyldopa, which are used in the treatment of Parkinson's disease in augmentation of L-DOPA to block the peripheral conversion of dopamine, thereby inhibiting undesirable side-effects, and as sympatholytic or antihypertensive agents.
[23] Other dopamine β-hydroxylase inhibitors include the centrally active nepicastat and the peripherally selective etamicastat and zamicastat.
Phenylalanine hydroxylase inhibitors like 3,4-dihydroxystyrene), which is currently only a research chemical with no suitable therapeutic indications, likely because such drugs would induce the potentially highly dangerous hyperphenylalaninemia or phenylketonuria.
