In the field of
pharmacology,
potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. A highly potent drug (e.g.,
fentanyl,
alprazolam,
risperidone) evokes a larger response at low concentrations, while a drug of lower potency (
codiene,
diazepam,
ziprasidone) evokes a small response at low concentrations. It is proportional to
affinity and
efficacy.