View source for Potency (pharmacology)

{{Short description|Measure of drug activity}}
{{ou|Potency (disambiguation)}}
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[[File:Potency Figure16.png|thumb|Concentration-response curves illustrating the concept of potency. For a response of 0.25a.u., Drug B is more potent, as it generates this response at a lower concentration. For a response of 0.75a.u., Drug A is more potent. a.u. refers to "arbitrary units".]]

In [[pharmacology]], '''potency''' or '''biological potency'''<ref>MILES AA, PERRY EL. Biological potency and its relation to therapeutic efficacy. Bull World Health Organ. 1953;9(1):1-14. PMID: 13082386; PMCID: PMC2542104.</ref> is a measure of a drug's [[biological activity]] expressed in terms of the dose required to produce a pharmacological effect of given intensity.<ref name=Neubig2003>{{cite journal | vauthors = Neubig RR, Spedding M, Kenakin T, Christopoulos A | url = https://pharmrev.aspetjournals.org/content/55/4/597 | title = International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification. XXXVIII. Update on terms and symbols in quantitative pharmacology | journal = Pharmacological Reviews | volume = 55 | issue = 4 | pages = 597–606 | date = December 2003 | pmid = 14657418 | doi = 10.1124/pr.55.4.4 | s2cid = 1729572}}</ref> A highly potent drug (e.g., [[fentanyl]], [[clonazepam]], [[risperidone]], [[benperidol]], [[bumetanide]]) evokes a given response at low concentrations, while a drug of lower potency (e.g. [[morphine]], [[alprazolam]], [[ziprasidone]], [[haloperidol]], [[furosemide]]) evokes the same response only at higher concentrations. Higher potency does not necessarily mean greater [[effectiveness]] nor more [[Adverse drug reaction|side effects]] nor less side effects.

==Types of potency==
The [[IUPHAR|International Union of Basic and Clinical Pharmacology]] (IUPHAR) has stated that "potency is an imprecise term that should always be further defined",<ref name=Neubig2003 /> and lists of types of potency as follows:

{| {{table}}
! Type of potency 
! Symbol
! Definition
|-
|[[ED-50|Effective dose]]
|<chem id="Effective dose">ED_{50}</chem>
|It is the minimum dose or concentration of a drug that produces a biological response in 50% of a population being studied.
|-
|[[LD50|Median lethal dose]]
|<chem>LD_{50}</chem>
|For either drugs or [[toxin]]s, it is a [[toxic unit]] that measures the minimum dose that causes death ([[lethal dose]]) in 50% of cases.
|-
|[[TD50|Median toxic dose]]
|<chem>TD_{50}</chem>
|It is the minimum dose at which toxicity occurs in 50% of cases.
|-
|[[EC50|Half maximal effective concentration]]
|<chem>EC_{50}</chem>
|It is a measure of the concentration of a [[drug]], [[antibody]] or [[toxicant]] which induces a biological response halfway between the baseline and maximum after a specified exposure time.<br> In other words, it can be defined as the concentration required to obtain a 50% effect.<ref>{{cite web|url=http://www.graphpad.com/curvefit/introduction89.htm |title=Introducing dose response curves |archive-url=https://web.archive.org/web/20120730150339/http://www.graphpad.com/curvefit/introduction89.htm |archive-date=2012-07-30 |publisher=Graphpad Software}}</ref>
|-
|[[IC50|Half maximal inhibitory concentration]]
|<chem>IC_{50}</chem>
|It is a measure of the potency of a substance in inhibiting a specific biological or biochemical function.
|}

==See also==
* [[Reaction inhibitor#Potency|Reaction inhibitor § Potency]]

==References==
{{reflist}}

==Further reading==
* {{cite news | first = Robert | last = Harris | title = Formulating High Potency Drugs | date = 2012-10-09 | url = http://www.contractpharma.com/issues/2012-10/view_features/formulating-high-potency-drugs/ | work = Contract Pharma | access-date = 2013-11-13}}
* {{cite book |vauthors=Walker MG, Page CP, Hoffman BF, Curtis M | title = Integrated Pharmacology | edition = 3rd| publisher = Mosby | location = St. Louis | year = 2006 | isbn = 978-0-323-04080-8 }}
https://www.addictioncenter.com/news/2019/08/15-most-dangerous-drugs/
https://nida.nih.gov/research-topics/commonly-used-drugs-charts#top
{{Pharmacology}}

[[Category:Pharmacodynamics]]