Agonist

Definition

An agonist is a substance that binds to a receptor and activates it to produce a biological response. Agonists can be drugs or endogenous compounds like hormones.

5 Must Know Facts For Your Next Test

1. Agonists mimic the action of naturally occurring substances in the body.
2. Full agonists fully activate the receptor they bind to, producing a maximal biological response.
3. Partial agonists activate receptors but produce a weaker, or partial, response compared to full agonists.
4. Agonists can influence pharmacokinetic properties such as absorption, distribution, metabolism, and excretion of drugs.
5. In endocrine disorders, agonists are often used to replace deficient hormones or stimulate hormone production.

Review Questions

• What is the primary function of an agonist in pharmacology?
• How do full agonists differ from partial agonists?
• Why might an agonist be used in treating endocrine disorders?

Related terms

Antagonist: A substance that binds to receptors but does not activate them, blocking the action of agonists.

Receptor: A protein molecule that receives chemical signals from outside a cell.

Efficacy: The ability of a bound drug to initiate a response at the molecular, cellular, tissue or system level.