Physiologic antagonism is when?

Physiologic antagonism is when?

• A. Two drugs affect same tissue from different receptors
• B. Two drugs affect different tissues
• C. One drug inhibits metabolism of another
• D. Two drugs produce opposing effects on the same tissue

Answer: (A)

Physiologic antagonism occurs when two drugs affect the same tissue but act through different receptors to produce opposite effects, counteracting each other at the tissue level without directly blocking the same receptor. A classic example is a drug that increases heart rate via beta-1 receptors and another drug that decreases heart rate via muscarinic receptors on the heart; they opposingly modulate the same organ through distinct receptor pathways. This distinguishes physiologic antagonism from blocking one receptor, altering drug metabolism, or affecting different tissues. Hence, two drugs acting on the same tissue from different receptors best describes physiologic antagonism.

Physiologic antagonism occurs when two drugs affect the same tissue but act through different receptors to produce opposite effects, counteracting each other at the tissue level without directly blocking the same receptor. A classic example is a drug that increases heart rate via beta-1 receptors and another drug that decreases heart rate via muscarinic receptors on the heart; they opposingly modulate the same organ through distinct receptor pathways. This distinguishes physiologic antagonism from blocking one receptor, altering drug metabolism, or affecting different tissues. Hence, two drugs acting on the same tissue from different receptors best describes physiologic antagonism.