antagonist


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antagonist

 [an-tag´o-nist]
antagonistic muscle. (see illustration.)
1. a substance that tends to nullify the action of another, as a drug that binds to a cellular receptor for a hormone, neurotransmitter, or another drug blocking the action of that substance without producing any physiologic effect itself. See also blocking agent.
2. a tooth in one jaw that articulates with one in the other jaw.
α-adrenergic antagonist alpha-adrenergic blocking agent.
β-adrenergic antagonist beta-adrenergic blocking agent.
folic acid antagonist see folic acid antagonist.
H1 receptor antagonist any of a large number of agents that block the action of histamine by competitive binding to the H1 receptor. Such agents also have sedative, anticholinergic, and antiemetic effects, the exact effect varying from drug to drug, and are used for the relief of allergic symptoms and as antiemetics, antivertigo agents, sedatives, and antidyskinetics in parkinsonism. This group is traditionally called the antihistamines.
H2 receptor antagonist an agent that blocks the action of histamine by competitive binding to the H2 receptor; used to inhibit gastric secretion in the treatment of peptic ulcer.

an·tag·o·nist

(an-tag'ŏ-nist),
Something opposing or resisting the action of another; certain structures, agents, diseases, or physiologic processes that tend to neutralize or impede the action or effect of others. Compare: synergist.

antagonist

(ăn-tăg′ə-nĭst)
n.
1. Physiology A muscle that counteracts the action of another muscle, the agonist.
2. A drug or chemical substance that interferes with the physiological action of another, especially by combining with and blocking its receptor.

an·tag′o·nis′tic adj.
an·tag′o·nis′ti·cal·ly adv.

antagonist

Anatomy
A muscle that opposes the movement of agonist muscles and returns a limb to its initial position.

Pharmacology
A substance that partially or completely nullifies the effect of another agent; a chemical entity that is not naturally found in the body which occupies a receptor, produces no physiologic effects and prevents endogenous and exogenous chemicals from producing an effect on that receptor.

an·tag·o·nist

(an-tag'ŏ-nist)
Something opposing or resisting the action of another; any structure, agent, disease, or physiologic process that tends to neutralize or impede some action or effect.
Compare: synergist

antagonist

1. A muscle that acts to oppose the action of another muscle (the agonist).
2. A drug that counteracts or neutralizes the action of another drug. The antonym of antagonist is agonist.

Antagonist

A substance that tends to nullify the action of another.
Mentioned in: Withdrawal Syndromes

antagonist 

1. An antagonistic muscle.
2. A substance (e.g. a drug, hormone or neurotransmitter) that depresses the action of an agonist or binds to a cell receptor without eliciting a physiological response (e.g. excitation or inhibition). Examples: atropine and hyoscine which block the effect of acetylcholine acting on cholinergic receptors and timolol which blocks adrenergic receptors. See agonist.

an·tag·o·nist

(an-tag'ŏ-nist)
Something opposing or resisting the action of another; certain structures, agents, diseases, or physiologic processes that tend to neutralize or impede the action or effect of others.
Compare: synergist
References in periodicals archive ?
Spring Bank has entered into a collaborative research agreement with the University of Texas Southwestern Medical Center for the evaluation of Spring Bank's STimulator of INterferon Gene (STING) antagonist compounds.
Senate Bill 200 amends the Public Health Code to allow a prescriber to dispense an opioid antagonist (naloxone/Narcan) to a public entity for purposes of the Administration of Opioid Antagonists Act.
- The first patient has been dosed in the first-in-human Phase 1 clinical trial evaluating BI 765063, formerly OSE-172, a first-in-class monoclonal antibody antagonist of SIRP?, being studied in patients with advanced solid tumors, German drugmaker Boehringer Ingelheim and France-based OSE Immunotherapeutics SA said.
Between January 2011 and December 2017, a total 354 women underwent intracytoplasmic sperm injection (ICSI) and controlled ovarian stimulation with an antagonist protocol at Ondokuz Mayis University Reproduction Unit.
According to research conducted at the Penn State College of Medicine, villains or the antagonists perform less amount of violence than the superheroes or the protagonists.
The researchers found that a larger proportion of cases than controls had prior PPI use (70 versus 63 percent) or histamine-2 receptor antagonist use (25 versus 23 percent).
The antagonist, in fact, does not need to make choices that the audience finds "not good." He or she merely needs to hinder the "good" choices of the protagonist.
BHV-5000 is reportedly a low trapping, potent N-methyl-D-aspartate (NMDA) receptor antagonist that has been licensed from AstraZeneca.
Studies that did not use animals, did not evaluate CINP, or evaluated noncannabinoid compounds without using cannabinoid receptor antagonists, reviews, commentaries, and in vitro studies were excluded.
Schaefer, "Angiotensin-II receptor 1 antagonist fetopathy--risk assessment, critical time period and vena cava thrombosis as a possible new feature," British Journal of Clinical Pharmacology, vol.
People who take proton pump inhibitors for stomach acid reflux run a greater risk of chronic kidney disease than those who take H2-receptor antagonists for the same complaint, a new study published in Gastroenterology reports.
The patients in Group A received HMG and GnRH antagonist for COH, while those in group B received only HMG.