<prompt> Therapeutic index of a drug is indicative ofMeasure of safetyMeasure of adverse effectDose range across which the drug can be safely administeredMeasure of efficacy  <response>: Ans: A Measure of safetyRef: Thripathi 5 ed. Pg. 46Therapeutic index is a measure of drug safety.Therapeutic index TDIt is the ratio of the dose that produces toxicity to the dose that produces a clinically desired or effective response. A large value indicates that there is a wide margin between doses that are effective and doses that are toxic.TD TD50ED50 TD50 is the dose that produces a toxic effect in half the population.ED 50 is the dose that produces a desired effect in half the population. 