Video - Pharmacodynamics: Agonist, partial agonist and antagonist

Depending on their effect on receptors in the body, drugs can be grouped into receptor agonists, partial agonists, and antagonists. An agonist is a drug that binds to a receptor and activates it, mimicking the effects of the body's natural ligands. It can have a full or high efficacy on the receptor. A partial agonist also binds to a receptor but only partially activates it. It has lower efficacy than a full agonist. An antagonist binds to a receptor but does not activate it. Instead, it blocks or interferes with the action of other ligands and drugs.