A novel compound binds the same receptor as norepinephrine but produces a peak effect only 30 percent as great. When it is co-administered with a full agonist at that receptor, the observed maximal response to the full agonist falls below its usual ceiling. The compound is best described as:
- A Competitive antagonist
- B Partial agonist ✓
- C Inverse agonist
- D Irreversible antagonist
Correct answer: B. Partial agonist
Explanation
A partial agonist has intrinsic activity between zero and one, producing a submaximal response alone and lowering the observed effect when a full agonist is present because it occupies receptors without fully activating them. An inverse agonist reduces signaling below basal constitutive activity rather than simply capping the agonist ceiling, and a competitive antagonist by itself elicits no response at all.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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