EC50

] Half maximal effective concentration (EC 50 ) 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. More simply, EC 50 can be defined as the concentration required to obtain a 50% [...] effect and may be also written as [A] 50 . It is commonly used as a measure of a drug's potency, although the use of EC 50 is preferred over that of 'potency', which has been criticised for its vagueness. EC 50 is a measure of concentration, expressed in molar units (M), where 1 M is equivalent to 1 mol/L. The EC 50 of a graded dose response curve therefore represents the concentration of a compound where 50% of its maximal effect is observed. The EC 50 of a quantal dose response curve represents the concentration of a compound where 50% of the population exhibit a response, after a specified exposure duration. For clarification, a graded dose response curve shows the graded effect of the drug (y axis) over the dose of the drug (x axis) in one or an average of subjects. A quantal dose response curve shows the percentage of subjects where a response is noted in an all-or-none manner (y axis) over the dose of the drug (x axis). For competition binding assays and functional antagonist assays IC 50 is the most common summary measure of the dose-response curve.…

] Half maximal effective concentration (EC 50 ) 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. More simply, EC 50 can be defined as the concentration required to obtain a 50% [...] effect and may be also written as [A] 50 . It is commonly used as a measure of a drug's potency, although the use of EC 50 is preferred over that of 'potency', which has been criticised for its vagueness. EC 50 is a measure of concentration, expressed in molar units (M), where 1 M is equivalent to 1 mol/L. The EC 50 of a graded dose response curve therefore represents the concentration of a compound where 50% of its maximal effect is observed. The EC 50 of a quantal dose response curve represents the concentration of a compound where 50% of the population exhibit a response, after a specified exposure duration. For clarification, a graded dose response curve shows the graded effect of the drug (y axis) over the dose of the drug (x axis) in one or an average of subjects. A quantal dose response curve shows the percentage of subjects where a response is noted in an all-or-none manner (y axis) over the dose of the drug (x axis). For competition binding assays and functional antagonist assays IC 50 is the most common summary measure of the dose-response curve. For agonist/stimulator assays the most common summary measure is the EC 50 . The EC 50 is also related to IC 50 which is a measure of a compound's inhibition (50% inhibition). There is a wide range of EC 50 values of drugs; they are typically anywhere from nM to mM. Hence, it is often more practical to refer to the logarithmically transformed pEC 50 values instead of EC 50 , where \ce{pEC50} = -\log_{10} (\ce{EC50}) . E = \frac{{[A]}^n \times {E_{\mathrm{max}}}} where E is the observed response or effect above baseline, and n, the Hill coefficient reflects the slope of the curve. The EC 50 represents the point of inflection of the Hill equation, beyond which increases of [A] have less impact on E. In dose response curves, the logarithm of [A] is often taken, turning the Hill equation into a sigmoidal logistic function. In this case, the EC 50 represents the rising section of the sigmoid curve.

Text derived from https://en.wikipedia.org/w/index.php?oldid=1315632972 under CC BY-SA 4.0; modifications have been made.