A partial agonist is one that, even at its highest dose, cannot achieve the same maximal response as a full agonist at the same receptor. 1. A full agonist achieves a maximal response when all its...

A partial agonist is one that, even at its highest dose, cannot achieve the same maximal response as a full agonist at the same receptor.

1. A full agonist achieves a maximal response when all its receptors are occupied.

2. Changes in receptor numbers can cause tolerance to drug effects.