AEMCA Practice Exam

After a non-competitive drug binds to its receptor, which of the following is true regarding agonist administration?

1. It can fully reverse the block

2. It is likely to have no effect in reversing the block

3. It enhances the non-competitive drug's effects

4. It increases receptor sensitivity

The correct answer is: It is likely to have no effect in reversing the block

When considering the effects of a non-competitive antagonist and the administration of an agonist, it's important to understand the mechanism of action of non-competitive antagonists. Non-competitive antagonists bind to the receptor in a way that reduces the maximum effect of an agonist, regardless of whether the agonist is present or not. This means that even if an agonist binds to the receptor after the non-competitive antagonist has done so, the agonist cannot fully restore the receptor's activity because the non-competitive antagonist has already occupied the receptor site or altered its conformation, preventing full activation. Thus, when an agonist is administered after a non-competitive antagonist, the expectation is that it is likely to have no significant effect in reversing the block. This inability to reverse the blockade is due to the nature of the non-competitive antagonism, which is characterized by the fact that the antagonist can effectively prevent the agonist from achieving its maximum effect, regardless of how much agonist is present. In contrast, options suggesting that the agonist can fully reverse the block, enhance the effects of the non-competitive drug, or increase receptor sensitivity do not accurately reflect the pharmacological interactions taking place. The agonist cannot overcome the effects of the