Antagonist (Receptor)
PharmacologyA molecule that binds a receptor and blocks it from activating — the opposite of an agonist (see 5-HT2A Receptor above). Most classic psychedelics are agonists; antagonists at the same receptor can block a trip entirely.
Example: Ketanserin, a 5-HT2A antagonist, is the standard tool researchers use to prove a drug's effects are specifically 5-HT2A-mediated: pretreating volunteers with 40mg of it completely blocks LSD's subjective effects, and giving it mid-trip measurably shortens the experience — in one placebo-controlled study, from 8.5 hours down to 3.5.
What is a receptor antagonist?
A molecule that binds a receptor and blocks it from activating — the opposite of an agonist. Most classic psychedelics are agonists; antagonists at the same receptor can block a trip entirely.
Can a drug block LSD's effects?
Yes — ketanserin, a 5-HT2A antagonist, is the standard tool researchers use to prove a drug's effects are specifically 5-HT2A-mediated: pretreating volunteers with 40mg of it completely blocks LSD's subjective effects, and giving it mid-trip measurably shortens the experience — in one placebo-controlled study, from 8.5 hours down to 3.5.