An antagonist binds irreversibly to the same receptor site as the agonist. Even with increasing agonist concentrations, the maximum response (Emax) cannot be restored. This describes which type of antagonism?

• A Competitive antagonism
• B Chemical antagonism
• C Physiological antagonism
• D Non-competitive antagonism ✓

Explanation

Non-competitive antagonism occurs when an antagonist binds irreversibly or at a different site, reducing the number of functional receptors and thus Emax. Increasing agonist concentration cannot overcome this. Competitive antagonism shifts the curve rightward but preserves Emax. Physiological antagonism involves different receptors producing opposite effects; chemical antagonism involves direct drug binding.

Reference: Rang and Dale's Pharmacology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.