nounIntermediate
Definition
The half-maximal inhibitory concentration: the concentration of a peptide or drug needed to inhibit a biological process by 50%.

Detailed Explanation

The half-maximal inhibitory concentration: the concentration of a peptide or drug needed to inhibit a biological process by 50%. IC₅₀ is a standard measure of potency in drug screening. Lower IC₅₀ = more potent. For example, a peptide with an IC₅₀ of 10 nM is 100× more potent than one with an IC₅₀ of 1 μM. IC₅₀ values are assay-dependent (unlike Ki, which is an intrinsic constant), so comparisons between studies require identical assay conditions.

Key Facts

  • The half-maximal inhibitory concentration: the concentration of a peptide or drug needed to inhibit a biological process by 50%.
  • IC₅₀ is a standard measure of potency in drug screening.
  • For example, a peptide with an IC₅₀ of 10 nM is 100× more potent than one with an IC₅₀ of 1 μM.
  • IC₅₀ values are assay-dependent (unlike Ki, which is an intrinsic constant), so comparisons between studies require identical assay conditions.
Related Terms Affinity Receptor Ligand

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