A dopamine agonist is a compound that activates dopamine receptor

Dopamine receptor

Dopamine receptors are a class of metabotropic G protein-coupled receptors that are prominent in the vertebrate central nervous system . The neurotransmitter dopamine is the primary endogenous ligand for dopamine receptors....

s in the absence of dopamine

Dopamine

Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

. Dopamine agonists activate signaling pathways through the dopamine receptor and trimeric G-proteins, ultimately leading to changes in gene transcription.

Uses

Some medical drug

Drug

A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...

s act as dopamine agonists and can treat hypodopaminergic (low dopamine) conditions; they are typically used for treating Parkinson's disease

Parkinson's disease

Parkinson's disease is a degenerative disorder of the central nervous system...

 and certain pituitary tumors (prolactinoma

Prolactinoma

A prolactinoma is a benign tumor of the pituitary gland that produces a hormone called prolactin. It is the most common type of pituitary tumor...

), and may be useful for restless legs syndrome

Restless legs syndrome

Restless legs syndrome or Willis-Ekbom disease is a neurological disorder characterized by an irresistible urge to move one's body to stop uncomfortable or odd sensations. It most commonly affects the legs, but can affect the arms, torso, and even phantom limbs...

 (RLS). Both Requip (Ropinirole

Ropinirole

Ropinirole is a non-ergoline dopamine agonist. It is manufactured by GlaxoSmithKline , Cipla and Sun Pharmaceutical. It is used in the treatment of Parkinson's disease...

) and Mirapex (Pramipexole

Pramipexole

Pramipexole is a non-ergoline dopamine agonist indicated for treating early-stage Parkinson's disease and restless legs syndrome...

) are FDA-approved for the treatment of RLS. There is also an ongoing clinical trial to test the effectiveness of the dopamine agonist Requip (ropinirole

Ropinirole

Ropinirole is a non-ergoline dopamine agonist. It is manufactured by GlaxoSmithKline , Cipla and Sun Pharmaceutical. It is used in the treatment of Parkinson's disease...

) in reversing the symptoms of SSRI-induced sexual dysfunction

Sexual dysfunction

Sexual dysfunction or sexual malfunction refers to a difficulty experienced by an individual or a couple during any stage of a normal sexual activity, including desire, arousal or orgasm....

 and Post-SSRI sexual dysfunction (PSSD). Additionally, a systematic review and meta-analysis concluded that prophylactic treatment with cabergoline reduces the incidence, but not the severity, of ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome is a complication from some forms of fertility medication. Most cases are mild, but a small proportion are severe.-Causative medications:...

 (OHSS), without compromising pregnancy outcomes, in females undergoing stimulated cycles of in vitro fertilization (IVF).

Side-effects

Some of the common side effects of dopamine agonists include:

• Euphoria
  Euphoria (emotion)
  Euphoria is medically recognized as a mental and emotional condition in which a person experiences intense feelings of well-being, elation, happiness, ecstasy, excitement and joy...
  
  
• Hallucination
  Hallucination
  A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
  
  s
• Causing or worsening psychosis
  Psychosis
  Psychosis means abnormal condition of the mind, and is a generic psychiatric term for a mental state often described as involving a "loss of contact with reality"...
  
  
• Orthostatic hypotension
  Orthostatic hypotension
  Orthostatic hypotension, also known as postural hypotension, orthostasis, and colloquially as head rush or dizzy spell, is a form of hypotension in which a person's blood pressure suddenly falls when the person stands up or stretches. The decrease is typically greater than 20/10 mm Hg, and may be...
  
  
• Increased orgasm
  Orgasm
  Orgasm is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure...
  
  ic intensity
• Weight loss
• Nausea
  Nausea
  Nausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
  
  
• Insomnia
  Insomnia
  Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...
  
  
• Unusual tiredness or weakness
• Dizziness, drowsiness, lightheadedness, or fainting
• Twitching, twisting, or other unusual body movements
• Pathological addiction (gambling, shopping, internet pornography, hyper-sexuality) – specifically D₃
  Dopamine receptor D3
  D dopamine receptor is a protein that in humans is encoded by the DRD3 gene.This gene encodes the D3 subtype of the dopamine receptor. The D3 subtype inhibits adenylyl cyclase through inhibitory G-proteins. This receptor is expressed in phylogenetically older regions of the brain, suggesting that...
  
  -preferring agonists

Examples

Examples of dopamine agonists include:

• Parlodel (bromocriptine
  Bromocriptine
  Bromocriptine , an ergoline derivative, is a dopamine agonist that is used in the treatment of pituitary tumors, Parkinson's disease , hyperprolactinaemia, neuroleptic malignant syndrome, and type 2 diabetes.- Indications :Amenorrhea, female infertility, galactorrhea, hypogonadism, and acromegaly...
  
  )
• Dostinex (cabergoline
  Cabergoline
  Cabergoline , an ergot derivative, is a potent dopamine receptor agonist on D2 receptors. In vitro, rat studies show cabergoline has a direct inhibitory effect on pituitary lactotroph cells...
  
  )
• Permax (pergolide
  Pergolide
  Pergolide is an ergoline-based dopamine receptor agonist used in some countries for the treatment of Parkinson's disease....
  
  ) - Removed from market in America March 29, 2007.

• Mirapex and Sifrol (pramipexole
  Pramipexole
  Pramipexole is a non-ergoline dopamine agonist indicated for treating early-stage Parkinson's disease and restless legs syndrome...
  
  )
• Requip (ropinirole
  Ropinirole
  Ropinirole is a non-ergoline dopamine agonist. It is manufactured by GlaxoSmithKline , Cipla and Sun Pharmaceutical. It is used in the treatment of Parkinson's disease...
  
  )
• Apokyn (apomorphine
  Apomorphine
  Apomorphine is a non-selective dopamine agonist which activates both D1-like and D2-like receptors, with some preference for the latter subtypes. It is historically a morphine decomposition product by boiling with concentrated acid, hence the -morphine suffix...
  
  )
• Neupro (rotigotine
  Rotigotine
  Rotigotine is a non-ergoline dopamine agonist indicated for the treatment of Parkinson's disease and restless legs syndrome in Europe and the United States...
  
  )
• Norprolac (Quinagolide
  Quinagolide
  Quinagolide is a selective, D2 receptor agonist that is used for the treatment of elevated levels of prolactin....
  
  )

Some, such as fenoldopam

Fenoldopam

Fenoldopam is a drug and synthetic benzazepine derivative which acts as a peripheral selective D1 receptor weak partial agonist/antagonist and is used as an antihypertensive. It was approved by the Food and Drug Administration in September 1997...

, are selective for dopamine receptor D1

Dopamine receptor D1

Dopamine receptor D1, also known as DRD1, is a protein that in humans is encoded by the DRD1 gene.- Function :This gene encodes the D1 subtype of the dopamine receptor. The D1 subtype is the most abundant dopamine receptor in the central nervous system. This G-protein-coupled receptor stimulates...

.

External links

• http://www.abc.net.au/news/stories/2008/01/22/2143502.htm
• http://neuro.psychiatryonline.org/cgi/content/full/19/4/473