<prompt> A drug that binds to a receptor at a site distinct from the active site and alters the affinity of the receptor for the endogenous ligand is a:-Competitive antagonistInverse againstPaial agonistAllosteric modulator  <response>: Allosteric modulator that binds to a receptor at a site distinct from the active site and alters the affinity of the receptor for the endogenous ligand. Competitive antagonist binds to the same site as that of agonist, produces surmountable effect i.e. effect of antagonist can be overcome by increasing concentration of agonist. Inverse agonist and paial agonist also bind to the same site as that of the agonist. 