<prompt> Ratio of median lethal dose to median effective dose is called?Drug potencyTherapeutic indexPotentiationTherapeutic efficacy  <response>: Therapeutic Index T.I.: T.I. LD50 ED50 It is a measure of the safety of a drug. It is calculated as a ratio of LD50 to ED50. Drugs having high T.I. are safer whereas those having low T.I. are more likely to be toxic. 