<prompt> Therapeutic drug monitoring must be done for:PenicillinPhenytoinErythromycinLignocaine  <response>: Ans. B. PhenytoinCharacteristics of drugs subject to therapeutic drug monitoringa. narrow therapeutic indexb. Relationship bw plasma drug concentration and pharmacological effectc. desired therapeutic effect difficult to monitord. defined therapeutic target concentration rangee. marked pharmacokinetic variabilityDrugs commonly monitoredTherapeutic rangeDigoxin0.5-1.4microgrLLithium0.6-1.2mmolLPhenytoin10-20mgLSodium valproate50-100mgLTheophylline5-15mgLAmiodarone1.0-2.5mgLLignocaine2.0-5.0mgL 