Agonists competitive

Antagonist A drug that binds to a biological receptor, but is unable to elicit the normally expected response. It prevents an agonist from binding to the same sits as that normally occupied by the agonist (competition), or at another site (allosterism). 

Fig. 4. Phenotype of the prArg389 and prGly389 receptors in transfected cells (A) and (B) results from agonist competition studies in washed membranes (C) (Continued on next page). (From ref. 4 with permission.)... 

Agonists, competitive antagonists, and competitive inverse agonists bind in the binding pocket of the receptor differently (have different structure-activity relationships and different pharmacophores), which leads to different structures for the receptor-ligand complex in each case. 

For competitive dualism combined with non-competitive antagonism the term multiple antagonism is used the drug acts as weakly active agonist, competitive antagonist and non-competitive antagonist... 

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