Pharmacology
IC50 (Half-Maximal Inhibitory Concentration)
Definition
IC50 is a quantitative pharmacological measure indicating the concentration of an inhibitor required to reduce a specific biological or biochemical function by 50%. It is widely used to characterize the potency of antagonists, enzyme inhibitors, and cytotoxic agents in dose-response studies. A lower IC50 value indicates greater potency, meaning less compound is needed to achieve half-maximal inhibition. IC50 values are context-dependent and can vary with assay conditions, substrate concentrations, and incubation times, so comparisons are most meaningful when determined under identical experimental conditions.