When a drug binds to a receptor to deactivate it, what is this drug acting as?

In pharmacology, when a drug binds to a receptor to deactivate it, it is acting as a non-competitive antagonist. Non-competitive antagonists bind to receptors in a way that prevents activation, regardless of the presence of other agonists. This means that even if an agonist is present, the receptor cannot be activated because the non-competitive antagonist has occupied the binding site or altered the receptor in such a way that it can no longer elicit a response.

This is distinct from competitive antagonists, which compete with agonists for the same binding site but allow the receptor to remain available for activation if agonists are present in sufficient quantities. Partial agonists have a mixed effect, activating the receptor but with less efficacy than a full agonist, while agonists fully activate receptors to produce their intended effect.

The specific interaction of non-competitive antagonists with receptors highlights their role in pharmacodynamics, providing important implications for drug action in various clinical scenarios.