antagonist(redirected from drug antagonist)
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1. any muscle that opposes the action of another
2. a drug that counteracts the effects of another drug
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
A molecule that bears sufficient structural similarity to a second molecule to compete with that molecule for binding sites on a third molecule.
A drug or other chemical substance capable of reducing the physiological activity of another chemical substance; refers especially to a drug that opposes the action of a drug or other chemical substance on the nervous system by combining with and blocking the nerve receptor.
A muscle that contracts with, and limits the action of, another muscle, called an agonist, with which it is paired.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.