A partial agonist binds to a receptor and produces a submaximal response even when all receptors are occupied. In the presence of a full agonist, a partial agonist at high concentration acts as:

• A An inverse agonist
• B A competitive antagonist ✓
• C A synergist
• D A non-competitive antagonist

Explanation

A partial agonist has intrinsic activity between zero and one. At high concentrations, it occupies receptors but produces less response than a full agonist would at the same occupancy. Thus, in the presence of a full agonist, a partial agonist reduces the overall response by competing for receptor binding sites, effectively acting as a competitive antagonist. This is seen with drugs like buprenorphine at opioid receptors.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.