Final answer:
The therapeutic index is the ratio of a medication's tolerated dose to its effective dose.
Step-by-step explanation:
The ratio of a medication's dose that can be tolerated to its effective dose is called the therapeutic index of the medication.
Therapeutic index is a measure of a drug's safety margin and is calculated by dividing the dose that can be tolerated (TD) by the effective dose (ED) needed to produce a desired therapeutic effect.
For example, if a medication has a therapeutic index of 10, it means that a patient can tolerate a dose that is 10 times higher than the effective dose.