Use Therapeutic Index when you need to compute the ratio of the toxic dose TD50 to the effective dose ED50. Enter Effective dose ED50 and Toxic dose TD50 using the definitions and units below so the result can be reproduced.

Effective dose ED50

A finite measured or assumed value.

Toxic dose TD50

A finite measured or assumed value.

The published tool contract uses this rule: Compute the ratio of the toxic dose TD50 to the effective dose ED50.^[1]

Therapeutic index

The calculated therapeutic index.

A ratio or percentage can conceal the scale of its numerator and denominator and becomes sensitive to measurement error when the denominator is small. It is informational and cannot diagnose a condition, select treatment, or replace professional interpretation of the original measurements.

Retain the original Effective dose ED50 and Toxic dose TD50 values and their units alongside the result. Selectivity Index is useful when you instead need to compute the ratio of toxic IC50 to therapeutic IC50 for a compound. Therapeutic Window Width provides another view by helping you measure the width of the therapeutic window as the toxic blood threshold minus the effective blood threshold, both in milligrams per decilitre.

• Selectivity Index

  Compute the ratio of toxic IC50 to therapeutic IC50 for a compound.

• Therapeutic Window Width

  Measure the width of the therapeutic window as the toxic blood threshold minus the effective blood threshold, both in milligrams per decilitre.

• Apoptotic Index

  Compute the apoptotic index as the ratio of apoptotic cells to mitotic cells.