partial agonist

Full Definition

A partial agonist is a type of receptor ligand that binds to and activates a receptor but has only partial efficacy at the receptor relative to a full agonist. Partial agonists can act as functional antagonists when competing with full agonists for the same receptor binding site. In psychopharmacology, this mechanism is particularly important for drugs like aripiprazole, which acts as a partial agonist at dopamine D2 receptors. This property allows for stabilization of neurotransmitter activity rather than simple blockade or activation.

Usage

Usage note: Distinguish from full agonists and antagonists in mechanism of action discussions.

In Context

• "Aripiprazole's partial agonist activity at dopamine receptors provides mood stabilization with reduced risk of hyperprolactinemia." — Pharmacology review
• "The partial agonist mechanism allows for functional modulation rather than complete receptor blockade." — Research article