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In pharmacology, potency or biological potency [1] is a measure of a drug's biological activity expressed in terms of the dose required to produce a pharmacological effect of given intensity. [2]
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. [3] EC 50 is a measure of concentration, expressed in molar units (M), where 1 M is equivalent to 1 mol/L.
Intrinsic activity (IA) and efficacy refer to the relative ability of a drug-receptor complex to produce a maximum functional response. This must be distinguished from the affinity, which is a measure of the ability of the drug to bind to its molecular target, and the EC 50, which is a measure of the potency of the drug and which is proportional to both efficacy and affinity.
The parameters of the dose response curve reflect measures of potency (such as EC50, IC50, ED50, etc.) and measures of efficacy (such as tissue, cell or population response). A commonly used dose–response curve is the EC 50 curve, the half maximal effective concentration, where the EC 50 point is defined as the inflection point of the curve.
In pharmacology, an effective dose (ED) or effective concentration (EC) is the dose or concentration of a drug that produces a biological response. [1] [2] The term "effective dose" is used when measurements are taken in vivo, while "effective concentration" is used when the measurements are taken in vitro.
Half maximal inhibitory concentration (IC 50) is a measure of the potency of a substance in inhibiting a specific biological or biochemical function. IC 50 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% ...
Potency is a measure of how much a drug is required in order to produce a particular effect. Therefore, only a small dosage of a high potency drug is required to induce a large response. The other terms used to measure the ability of a drug to trigger a response are: Intrinsic Activity which defines: Agonists as having Intrinsic Activity = 1
In the above equation, the greater the difference between ED 50 and TD 50, the greater the value of TI efficacy. Hence, a lower efficacy-based therapeutic index indicates a larger therapeutic window. Protective index. Similar to safety-based therapeutic index, the protective index uses TD 50 (median toxic dose) in place of LD 50.