Partial agonist -

• a drug that has a lower maximal response resulting from lower efficacy

Allosteric modulators -

• bind to proteins at sites other than the binding site for the principle agonist, they can either:
  • alter the affinity of the binding site for its agonists
  • change the efficacy of the response when the agonist binds
• Their action can be either:
  • positive (increase potency of agonists)
  • negative (decrease the potency of agonists)