agonist

drug

Also known as: agonism

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June 18, 2026

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An agonist is a substance that binds to a cell's receptor and initiates the same activity that the body's own substances typically produce. Drugs can act as agonists, mimicking the effects of natural compounds like hormones or neurotransmitters. For example, certain drugs are described as dopaminergic agonists, meaning they activate dopamine receptors.12

Agonists have both affinity (the tendency to bind to a receptor) and efficacy (the ability to produce a response). This contrasts with antagonists, which can bind to receptors but do not elicit a response, thereby blocking the action of agonists. Adrenergic drugs, for instance, can be agonists that stimulate the sympathetic nervous system by mimicking the effects of norepinephrine and epinephrine.23

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pharmaceutical industry
Contribution of scientific knowledge to drug discovery
Agonists are drugs or naturally occurring substances that activate physiologic receptors, whereas antagonists are drugs that block those receptors. In this case, angiotensin II is an agonist at AT1 receptors, and the antihypertensive AT1 drugs are antagonists. Antihypertensives illustrate the value of discovering novel drug…
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Agonists are drugs or naturally occurring substances that activate physiologic receptors, whereas antagonists are drugs that block those receptors. In this case, angiotensin II is an agonist at AT1 receptors, and the antihypertensive AT1 drugs are antagonists. Antihypertensives illustrate the value of discovering novel drug…
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drug
Receptors
…receptor is classified as an agonist or as an antagonist. A drug whose efficacy and affinity are sufficient for it to be able to bind to a receptor and affect cell function is an agonist. A drug with the affinity to bind to a receptor but without the efficacy to…
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…receptor is classified as an agonist or as an antagonist. A drug whose efficacy and affinity are sufficient for it to be able to bind to a receptor and affect cell function is an agonist. A drug with the affinity to bind to a receptor but without the efficacy to…
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receptor
…called ligands, can function as agonists, which stimulate the receptor to transmit signal information, or as antagonists, which inhibit, or prevent, the receptor from transmitting information. Antagonists can compete with agonists and thereby block an agonist’s action. As therapeutic agents, both agonists and antagonists have been useful. For example, the…
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…called ligands, can function as agonists, which stimulate the receptor to transmit signal information, or as antagonists, which inhibit, or prevent, the receptor from transmitting information. Antagonists can compete with agonists and thereby block an agonist’s action. As therapeutic agents, both agonists and antagonists have been useful. For example, the…
Read More