<prompt> Which drug has wide therapeutic indexDigoxinLithiumPhenytoinPenicillin  <response>: Ans. is d i.e., Penicillin The therapeutic index of a drug is the ratio of the dose that produces toxicity to the dose that produces a clinic desired or effective response in population of individuals. Therapeutic index Toxic dose Effective dose The therapeutic index is thus a measure of the drugs safety, since a large value indicates that there is wide margin between doses that are effective and that are toxic.Phenytoin has narrow therapeutic index page 372, 5the K.D.T.Lithium has narrow therapeutic index page 416, 5the K.D.T.Digitalis has narrow therapeutic index page 462, 5the K.D.T. 