Ratio of median lethal dose to median effective dose is called?: (A) Drug potency, (B) Therapeutic index, (C) Potentiation, (D) Therapeutic efficacy
Answer is B. 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.