An antagonist is a compound that blocks or inhibits an innate biological response by binding to and blocking a receptor site rather than activating it. Antagonistic drugs are sometimes referred to as “Blockers” and include the following:
- Beta-Blockers
- ACE Inhibitors
- MAO-I Inhibitors
- Proton Pump Inhibitors (H2 Blockers)
Antagonists exert their influence on receptor sites both directly, by binding to them, and indirectly through interaction with other compounds and/or biological pathways (allosteric sites.) In some cases, a receptor antagonist exerts significant influence over receptor functioning via pathways that aren’t normally attributed to the functioning of that receptor site—in other words; indirectly.
There are several types of antagonists including competitive, non-competitive, and uncompetitive. Depending on their function, such antagonist differences are made by accordance with permanent bonding, competition with other receptor antagonists, and the requirements for pre-activation of receptor sites before binding.