Drug–Receptor Scenarios & Dose–Response Curve Effects

Vocabulary flashcards covering key drug–receptor concepts from the lecture notes.

Full Agonist

Binds to the orthosteric site and produces maximal receptor activation when all receptors are occupied; yields a standard sigmoidal dose–response curve with Emax.

Partial Agonist

Binds orthosteric site; activates receptor but with submaximal efficacy despite full occupancy; lower Emax and variable EC50.

Inverse Agonist

Binds orthosteric site; reduces receptor activity below basal constitutive activity; dose–response curve decreases below baseline.

Neutral Antagonist

Binds orthosteric site; blocks agonist binding without altering basal activity; alone yields a flat line; in presence of agonist, shifts the agonist curve to the right with Emax unchanged.

Competitive Antagonist (reversible)

Binds orthosteric site reversibly; competes with agonist and can be overcome by higher agonist concentration; causes a rightward shift in the agonist curve (EC50↑), Emax unchanged.

Irreversible Antagonist (orthosteric, covalent)

Binds orthosteric site covalently or with extremely high affinity; permanently blocks receptors, reducing available receptors; Emax reduced; EC50 may or may not change.

Non-Competitive Antagonist (allosteric)

Binds allosteric site; prevents receptor activation by agonist regardless of concentration; Emax reduced; curve shifts downward; EC50 may or may not change.

Positive Allosteric Modulator (PAM)

Binds allosteric site; enhances agonist affinity and/or efficacy; curve shifts left (lower EC50) and may increase Emax.

Negative Allosteric Modulator (NAM)

Binds allosteric site; decreases agonist affinity and/or efficacy; curve shifts right (higher EC50) and may reduce Emax.

Allosteric Agonist (Ago-Allosteric Ligand)

Binds allosteric site; directly activates receptor without orthosteric ligand; yields an agonist-like curve and may act synergistically with endogenous ligand.

Silent Allosteric Modulator (SAM)

Binds allosteric site; has no intrinsic effect on receptor activity but blocks PAM/NAM binding; no shift alone but blocks modulation from other allosteric ligands.

Bitopic Ligand

Simultaneously engages both orthosteric and allosteric sites; can activate or modulate in a subtype-selective manner; curve depends on design with EC50/Emax shifts reflecting both components.