<prompt> TherapeutIc index is a measure of:SafetyPotencyEfficacySelectivity  <response>: The gap between the therapeutic effect DRC Dose Response Curveand the adverse effect DRC defines the safety margin or the therapeutic index of a drug. So it is a measure of safety Therapeutic index median lethal dose median effective dose or LD 50 ED 50 Ref; KD Tripathi Pharmacology 7th edition page no;56 