Antagonist

Definition

An antagonist is a substance that binds to a receptor but does not activate it, thereby blocking the action of agonists or endogenous substances. In pharmacology, antagonists are often used to inhibit the effects of other drugs or physiological processes.

5 Must Know Facts For Your Next Test

1. Antagonists can be competitive or non-competitive based on how they bind to receptors.
2. Competitive antagonists bind reversibly to receptors and can be overcome by increasing the concentration of an agonist.
3. Non-competitive antagonists bind irreversibly or allosterically, reducing the maximum response achievable by any amount of agonist.
4. Antagonists are crucial in treating conditions like hypertension and anxiety by blocking specific neurotransmitters or hormones.
5. Understanding the difference between an antagonist and an agonist is key in determining drug interactions and therapeutic outcomes.

Review Questions

• What is the primary function of an antagonist in pharmacology?
• How do competitive and non-competitive antagonists differ in their mechanisms of action?
• Why might a healthcare provider choose to use an antagonist in treatment?

Related terms

Agonist:

A substance that activates a receptor to produce a biological response.

Partial Agonist:

A substance that partially activates a receptor, producing a weaker response than a full agonist.

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