Editing Inverse agonist (section)

{{Short description|Agent in biochemistry}}
{{distinguish|Antagonist (disambiguation){{!}}Antagonist|Protagonist (disambiguation){{!}}Protagonist}}
[[Image:Inverse agonist 3.svg|thumb|400 px|Dose response curves of a full agonist, partial agonist, neutral antagonist, and inverse agonist]]
In [[pharmacology]], an '''inverse agonist''' is a [[drug]] that binds to the same [[receptor (biochemistry)|receptor]] as an [[agonist]] but induces a pharmacological response opposite to that of the agonist.

A [[receptor antagonist|neutral antagonist]] has no activity in the absence of an agonist or inverse agonist but can block the activity of either;<ref>{{cite journal | vauthors = Kenakin T | title = Principles: receptor theory in pharmacology | journal = Trends in Pharmacological Sciences | volume = 25 | issue = 4 | pages = 186–92 | date = April 2004 | pmid = 15063082 | doi = 10.1016/j.tips.2004.02.012 }}</ref> they are in fact sometimes called ''blockers'' (examples include [[alpha blocker]]s, [[beta blocker]]s, and [[calcium channel blocker]]s). Inverse agonists have opposite actions to those of agonists but the effects of both of these can be blocked by antagonists.<ref name="pmid27955830">{{cite journal | vauthors = Nutt D, Stahl S, Blier P, Drago F, Zohar J, Wilson S |author-link1=David Nutt |title = Inverse agonists - What do they mean for psychiatry? | journal = European Neuropsychopharmacology | volume = 27 | issue = 1 | pages = 87–90 | date = January 2017 | pmid = 27955830 | doi = 10.1016/j.euroneuro.2016.11.013 | hdl = 10044/1/43624 |s2cid=25113284 | hdl-access = free }}</ref>

A prerequisite for an inverse agonist response is that the receptor must have a [[receptor (biochemistry)#Constitutive activity|constitutive]] (also known as [[intrinsic activity|intrinsic]] or basal) level of activity in the absence of any [[ligand (biochemistry)|ligand]].<ref>{{Cite journal|last1=Berg|first1=Kelly A|last2=Clarke|first2=William P|date=2018-08-06|title=Making Sense of Pharmacology: Inverse Agonism and Functional Selectivity|journal=International Journal of Neuropsychopharmacology|volume=21|issue=10|pages=962–977|doi=10.1093/ijnp/pyy071|issn=1461-1457|pmc=6165953|pmid=30085126}}</ref> An agonist increases the activity of a receptor above its basal level, whereas an inverse agonist decreases the activity below the basal level.

The [[efficacy]] of a full agonist is by definition 100%, a neutral antagonist has 0% efficacy, and an inverse agonist has < 0% (i.e., negative) efficacy.