A non-competitive antagonist differs from a competitive antagonist in that it:

• A Shifts the agonist dose-response curve to the right without changing Emax
• B Binds irreversibly or at an allosteric site, reducing the maximal response of the agonist ✓
• C Can be overcome by increasing the agonist concentration
• D Increases the EC50 of the agonist without affecting efficacy

Explanation

A non-competitive antagonist either binds irreversibly to the agonist site or binds an allosteric site, reducing the number of functional receptors or the receptor-effector coupling. This decreases the maximal response (Emax) of the agonist, and the effect cannot be overcome by increasing agonist concentration. Phenoxybenzamine at alpha-adrenergic receptors is the classic example.

Reference: Katzung and Trevor's Pharmacology: Examination and Board Review, 13th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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