Equipotent molar ratio

The Equipotent Molar Ratio (EPMR) is the ratio of the molar concentrations of one drug divided by another standard drug such that both drugs give a sub-maximal response. This is best done at 50% of the maximum response on a Dose-response relationship, where the line is most linear. The standard drug should be used as the denominator for the calculation.

Typically this is used to compare the efficacy of drugs for a specific receptor.