Antagonists & Spare receptor theory

Antagonist
Anything that inhibits the action of agonist in the system
-includes chemical, physiological, pharmacological

Chemical antagonist
-is a drug that doesn’t act through a receptor.
-example is Chelating agent take the agonist out of the system, does not act through receptor mechanism

Physiological antagonist
-act through receptor but not the same receptor as of the agonist
-both of these drugs are agonist at their own receptor.
-but they antagonize each other’s effect