Potency (pharmacology)

In pharmacology, potency is a measure of a drug's biological activity expressed in terms of the dose required to produce a pharmacological effect of given intensity.[1] A highly potent drug (e.g., fentanyl, alprazolam, risperidone, ) evokes a given response at low concentrations, while a drug of lower potency (meperidine, ziprasidone, furosemide) evokes the same response only at higher concentrations. Higher potency does not necessarily mean greater effectiveness or more side effects.

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".

The IUPHAR has stated that 'potency' is "an imprecise term that should always be further defined",[1] and lists of types of potnecy as follows:

Type of potency Symbol Definition
Effective dose It is the minimum dose or concentration of a drug that produces a biological response in 50% of a population being studied.
Median lethal dose For either drugs or toxins, it is a toxic unit that measures the minimum dose that causes death (lethal dose) in 50% of cases.
Median toxic dose It is the minimum dose at which toxicity occurs in 50% of cases.
Half maximal effective concentration 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.
Half maximal inhibitory concentration It is a measure of the potency of a substance in inhibiting a specific biological or biochemical function.

See alsoEdit


  1. ^ a b Neubig RR, Spedding M, Kenakin T, Christopoulos A (December 2003). "International Union of Pharmacology Committee on Receptor Nomenclature and Drug Classification. XXXVIII. Update on terms and symbols in quantitative pharmacology". Pharmacol Rev. 55 (4): 597–606. doi:10.1124/pr.55.4.4. PMID 14657418. S2CID 1729572.

Further readingEdit

https://www.addictioncenter.com/news/2019/08/15-most-dangerous-drugs/ https://nida.nih.gov/research-topics/commonly-used-drugs-charts#top