digplanet beta 1: Athena
Share digplanet:


Applied sciences






















For other meanings of "agonist" or "agonism", see agonist (disambiguation). For a primary fictional character in a work, see Protagonist and Antagonist.
Agonists activating hypothetical receptors.
Efficacy spectrum of receptor ligands.

An agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response. Whereas an agonist causes an action, an antagonist blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist.

Types of agonists[edit]

Receptors can be activated by either endogenous (such as hormones and neurotransmitters) or exogenous (such as drugs) agonists, resulting in a biological response. A physiological agonist is a substance that creates the same bodily responses but does not bind to the same receptor.

An endogenous agonist for a particular receptor is a compound naturally produced by the body that binds to and activates that receptor. For example, the endogenous agonist for serotonin receptors is serotonin, and the endogenous agonist for dopamine receptors is dopamine.[1]

A superagonist is a compound that is capable of producing a greater maximal response than the endogenous agonist for the target receptor, and thus has an efficacy of more than 100%. This does not necessarily mean that it is more potent than the endogenous agonist, but is rather a comparison of the maximum possible response that can be produced inside the cell following receptor binding.

Full agonists bind (have affinity for) and activate a receptor, producing full efficacy at that receptor. One example of a drug that acts as a full agonist is isoproterenol, which mimics the action of adrenaline at β adrenoreceptors. Another example is morphine, which mimics the actions of endorphins at μ-opioid receptors throughout the central nervous system.

Partial agonists (such as buspirone, aripiprazole, buprenorphine, or norclozapine) also bind and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist, even at maximal receptor occupancy. Agents like buprenorphine are used to treat opiate dependence for this reason, as they produce milder effects on the opioid receptor with lower dependence and abuse potential.

An inverse agonist is an agent that binds to the same receptor binding-site as an agonist for that receptor and inhibits the constitutive activity of the receptor. Inverse agonists exert the opposite pharmacological effect of a receptor agonist, not merely an absence of the agonist effect as seen with antagonist. An example is the cannabinoid inverse agonist rimonabant.

A co-agonist works with other co-agonists to produce the desired effect together. NMDA receptor activation requires the binding of both glutamate, glycine and D-serine co-agonists.

An irreversible agonist is a type of agonist that binds permanently to a receptor through the formation of covalent bonds. A few of these have been described.[2][3]

A selective agonist is selective for a specific type of receptor. E.g. buspirone is a selective agonist for serotonin 5-HT1A.

New findings that broaden the conventional definition of pharmacology demonstrate that ligands can concurrently behave as agonist and antagonists at the same receptor, depending on effector pathways or tissue type. Terms that describe this phenomenon are "functional selectivity", "protean agonism",[4][5] or selective receptor modulators.[6]



The potency of an agonist is inversely related to its EC50 value. The EC50 can be measured for a given agonist by determining the concentration of agonist needed to elicit half of the maximum biological response of the agonist. The EC50 value is useful for comparing the potency of drugs with similar efficacies producing physiologically similar effects. The smaller the EC50 value, the greater the potency of the agonist, the lower the concentration of drug that is required to elicit the maximum biological response.

Therapeutic index[edit]

When a drug is used therapeutically, it is important to understand the margin of safety that exists between the dose needed for the desired effect and the dose that produces unwanted and possibly dangerous side-effects (measured by the TD50, the dose that produces toxicity in 50% of individuals). This relationship, termed the therapeutic index, is defined as the ratio TD50:ED50. In general, the narrower this margin, the more likely it is that the drug will produce unwanted effects. The therapeutic index emphasizes the importance of the margin of safety, as distinct from the potency, in determining the usefulness of a drug.


From the Greek αγωνιστής (agōnistēs), contestant; champion; rival < αγων (agōn), contest, combat; exertion, struggle < αγω (agō), I lead, lead towards, conduct; drive

See also[edit]


  1. ^ Goodman and Gilman's Manual of Pharmacology and Therapeutics. (11th edition, 2008). p14. ISBN 0-07-144343-6
  2. ^ De Mey JGR, Compeer MG, Meens MJ (2009). "Endothelin-1, an Endogenous Irreversible Agonist in Search of an Allosteric Inhibitor". Mol Cell Pharmacol 1 (5): 246–257. 
  3. ^ Rosenbaum DM, Zhang C, Lyons JA, Holl R, Aragao D, Arlow DH, Rasmussen SG, Choi HJ, Devree BT, Sunahara RK, Chae PS, Gellman SH, Dror RO, Shaw DE, Weis WI, Caffrey M, Gmeiner P, Kobilka BK (January 2013). "Structure and function of an irreversible agonist-β(2) adrenoceptor complex". Nature 469 (7329): 236–40. doi:10.1038/nature09665. PMID 21228876. 
  4. ^ Kenakin T (March 2001). "Inverse, protean, and ligand-selective agonism: matters of receptor conformation". FASEB J. 15 (3): 598–611. doi:10.1096/fj.00-0438rev. PMID 11259378. 
  5. ^ Urban JD, Clarke WP, von Zastrow M, Nichols DE, Kobilka B, Weinstein H, et al. (January 2007). "Functional selectivity and classical concepts of quantitative pharmacology". J. Pharmacol. Exp. Ther. 320 (1): 1–13. doi:10.1124/jpet.106.104463. PMID 16803859. 
  6. ^ Smith CL, O'Malley BW (February 2004). "Coregulator function: a key to understanding tissue specificity of selective receptor modulators". Endocr. Rev. 25 (1): 45–71. doi:10.1210/er.2003-0023. PMID 14769827. 

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Agonist — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
148384 videos foundNext > 


THE AGONIST - Panophobia (OFFICIAL VIDEO). Taken from the album "Prisoners". Century Media 2012. Get it now! http://smarturl.it/AgonistPrisiTunes.


THE AGONIST - Disconnect Me (LYRIC VIDEO). New single on sale at iTunes April 28th (EU) / 29th (US)! THE AGONIST is: Vicky Psarakis - Vocals Danny Marino - G...

THE AGONIST - and Their Eulogies Sang Me to Sleep (OFFICIAL)

THE AGONIST - and Their Eulogies Sang Me to Sleep (OFFICIAL VIDEO). Taken from the album 'Lullabies for the Dormant Mind' (2009, Century Media CMDistro - htt...


THE AGONIST - Thank You Pain (OFFICIAL VIDEO). Taken from the album "Lullabies For The Dormant Mind", Century Media Records 2009.

Prisoners (Full Album) ~ The Agonist

The Agonist's newest album: Prisoners 1. You're Coming With Me 0:03 - 5:35 2. The Escape 5:36 - 9:44 3. Predator & Prayer 9:45 - 14:48 4. Anxious Darwinians ...

THE AGONIST - Business Suits and Combat Boots (OFFICIAL VIDEO)

THE AGONIST - Business Suits and Combat Boots. Taken from the album "Once Only Imagined", Century Media Records 2007. CMDistro - http://www.cmdistro.com/Item...


she can get inspire from her.....

The Agonist - Perpetual Notion

The Agonist new song.

Thank You, Pain - Vicky Psarakis (The Agonist New Singer Original Cover)

For those Agonist fans who didn't get a chance to check out their new singer's original cover of "Thank You, Pain" - you deserve to know. Enjoy.

The Agonist - Lullabies For The Dormant Mind (Album Completo / Full Album)

Me seguis? gracias :D http://www.facebook.com/AquiEstaSuDisco Este canal esta especialmente a la musica de todos los generos menos la cumbia xD (lo digo ense...

148384 videos foundNext > 

948 news items

Tue, 22 Jul 2014 02:47:23 -0700

A team of researchers from the USA has developed a novel small-molecule Gpr120 agonist, cpdA, that has anti-inflammatory and insulin-sensitizing effects similar to ω-3 fatty acids in obese mice. ω-3 fatty acids are known to have anti-inflammatory ...


Wed, 09 Jul 2014 15:00:29 -0700

The Agonist will release their latest album 'Eye of Providence' on Nov. 11 via Century Media Records. It will be the Canadian band's fourth studio album, and first with new vocalist Vicky Psarakis. She replaced Alissa White-Gluz, who is now with Arch ...
ADVANCE for Physician Assistants
Tue, 01 Jul 2014 16:42:21 -0700

Current ADA/EASD guidelines recommend the following therapies as possible add-ons to metformin and basal insulin: a thiazolidinedione (pioglitazone), a DPP-4 inhibitor, or a GLP-1 agonist.1 If the patient is experiencing excessive PPG excursions ...
Sun, 13 Jul 2014 05:15:32 -0700

On Thursday The Agonist Reveal New Album Details was a top story. Here is the recap: The Agonist have released a new studio update for their forthcoming album, "Eye Of Providence" which they will be releasing on November 11th in North America and on ...
Doctors Lounge
Fri, 11 Jul 2014 10:03:45 -0700

Using distinct protocols, a K/BxN serum model of inflammatory arthritis was applied, and modulation of joint disruption was compared for the MC3 agonist DTrp8-γ-melanocyte stimulating hormone (DTrp) versus dexamethasone and calcitonin.

ZME Music

ZME Music
Thu, 10 Jul 2014 06:57:52 -0700

The Canadian melodic death metal band, The Agonist, finally decided to share the release date of their upcoming most awaited album, Eye of Providence. It seems that the album will be available starting November 10th and you might want to know that this ...

New York Times

New York Times
Fri, 25 Jul 2014 08:33:45 -0700

As I began Brando Skyhorse's “Take This Man,” I thought, Ah, another New Agonist! New Agonists serve the kettle corn of memoir, candy you can't put down. But often, at book's end, there's little to do except swap horrors: “Can you believe the part ...
The Pharmaceutical Journal
Fri, 25 Jul 2014 08:33:45 -0700

Olodaterol, a once-daily long acting β2-agonist (LABA) inhaler, has been launched in the UK as an additional treatment option for chronic obstructive pulmonary disease (COPD). The treatment is indicated as a maintenance bronchodilator treatment in ...

Oops, we seem to be having trouble contacting Twitter

Talk About Agonist

You can talk about Agonist with people all over the world in our discussions.

Support Wikipedia

A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia. Please add your support for Wikipedia!