Eudysmic ratio
The eudysmic ratio (also spelled eudismic ratio) is a term commonly found in the fields of pharmacology, chemistry, and molecular biology which describes the difference in pharmacologic activity between the two enantiomers of a drug.
When enantiomers are formed non-selectively and the resulting product contains an equal quantity of each enantiomer it is called a racemic mixture.
In pharmacology it is frequently, though not always, the case that one enantiomer of a chiral drug has greater pharmacological activity than the other. The eudysmic ratio is a mathematical equation that quantitatively measures the difference in this activity. A eudysmic ratio significantly differing from 1 means that there is a difference in activity between the two enantiomers.
Terminology
The eutomer is the chiral enantiomer having the desired pharmacological activity, e.g., as an active ingredient in a drug.
The distomer, on the other hand, is the enantiomer of the eutomer which may have undesired bioactivity or may be bio-inert.
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