Which term describes a drug that produces a weaker response than a full agonist?

• A. Antagonist
• B. Inverse agonist
• C. Partial agonist
• D. Agonist

Answer: (C)

When a drug binds a receptor and activates it but produces less than the maximal possible effect, it is a partial agonist. This means it has activation (intrinsic activity) but not enough to elicit a full response, even if all receptors are occupied. Partial agonists can still produce a detectable effect, but the ceiling is below that of a full agonist.

In contrast, an antagonist binds without activating the receptor, blocking other compounds from binding. An inverse agonist actually reduces baseline receptor activity below its normal level. A full agonist, by definition, produces the maximum possible response.