A pharmacological paradox: May a neutral antagonist shift an agonist concentration-response curve to the left?

Abstract

It is generally accepted that the presence of a competitive antagonist shifts an agonist concentration-response curve to the right. However, this may not always be the case: The concentration-response curve of an inverse receptor agonist may be shifted to the left by a neutral antagonist; a condition, which can be hypothetically explained by the assumption of both negative cooperativity of dimeric receptors plus a receptor reserve. © 2014 Springer-Verlag.