Competitive antagonist: Shifts curve right (↓ potency), no change in efficacy. Can be overcome by ↑ the concentration of agonist substrate.- Example: Diazepam (agonist) + flumazenil (competitive antagonist) on GABA receptor.

Noncompetitive antagonist: Shifts curve down (↓ efficacy). Cannot be overcome by ↑ agonist substrate concentration.- Example: Norepinephrine (agonist) + phenoxybenzamine (noncompetitive antagonist) on α-receptors.

Partial agonist: Acts at same site as full agonist, but with lower maximal effect (↓ efficacy). Potency is an independent variable.- Example: Morphine (full agonist) vs buprenorphine (partial agonist) at opioid μ-receptors.