IC50: Difference between revisions

[[File:IC50 determination illustration.png|thumb|Graphical representation of the IC50 determination of the inhibition of an enzyme's activity by a small molecule ("drug"). Four different concentrations of the small molecule (ranging from 30 to 300 μM) were tested.]]'''Half maximal inhibitory concentration (IC₅₀)''' is a measure of the potency of a substance in inhibiting a specific biological or biochemical function. IC₅₀ is a quantitative measure that indicates how much of a particular inhibitory substance (e.g. drug) is needed to inhibit, ''in vitro'', a given biological process or biological component by 50%. The biological component could be an enzyme, cell, cell receptor or microorganism. IC₅₀ values are typically expressed as [[molar concentration]].

IC₅₀ is commonly used as a measure of antagonist drug potency in pharmacological research. IC₅₀ is comparable to other measures of potency, such as [[half maximal effective concentration|EC₅₀]] for [[agonist|excitatory drugs]]. EC₅₀ represents the dose or plasma concentration required for obtaining 50% of a maximum effect ''in vivo''.