| (A) Competitive antagonist |
↓ |
No change |
Can be overcome by ↑ agonist concentration |
Diazepam (agonist) + flumazenil (competitive antagonist) on GABAₐ receptor. |
| (B) Noncompetitive antagonist |
No change |
↓ |
Cannot be overcome by ↑ agonist concentration |
Norepinephrine (agonist) + phenoxybenzamine (noncompetitive antagonist) on α-receptors. |
| (C) Partial agonist (alone) |
Independent |
↓ |
Acts at same site as full agonist |
Morphine (full agonist) vs buprenorphine (partial agonist) at opioid μ-receptors. |
| Inverse agonist (alone) |
Independent |
Independent |
Binds to a constitutively active receptor, thereby reducing its activity; has the opposite effect of an agonist |
H₁ antihistamines (eg, diphenhydramine) |
