Competitive antagonists

[Lothric]

Hey

FA says that competitive antagonists can be overcome by increasing the agonist concentration.

That statement is only valid if the competitive antagonist is reversible, right? It seems like reversible/irreversible are terms only used for inhibitors (not antagonists), but they can be applied for antagonists if I'm not wrong.

If yes, why is FA not specific and say "Agonist with a competitive REVERSIBLE antagonist" can be overcome by increasing the agonist c?

---

Members don't see this ad.

 

[Lothric]

An antagonist that binds irreversibly to an active site of a receptor is considered to be a form of non-competitive antagonism.

Therefore, competitive antagonists should be assumed to bind reversibly to the active site of a receptor unless explicitly stated otherwise.

I thought non-competitive inhibitors (and therefore antagonists in this case) were defined by not binding to the active site. FA literally states that. This is confusing.

So in general competitive antagonists are reversible and noncompetitive antagonists are irreversible unless stated otherwise.

 

[Lothric]

There are two forms of non-competitive antagonism:
1) An antagonist binding irreversibly to an active site of a receptor (this type can also be called irreversible competitive antagonism)
2) An antagonist binding to an allosteric site of a receptor (either reversibly or irreversibly)
Both of these actions act the same by wiping out that receptor. With the receptor wiped out, no additional agonist will be able to be acted on by that receptor.


Competitive antagonists (unless explicitly said to be irreversible) should be assumed to be reversible. These receptors are not wiped out, and therefore the effect of the antagonist can be overcome by the addition of more agonist.

Thanks Huggy, you've made it clear!