<prompt> Therapeutic drug monitoring is used in -DiureticMetforminLevodopaDigoxin  <response>: Ans. is d i.e., Digoxin Therapeutic drug monitoring is particularly useful in following situations -1. Drugs with low safety margin -a Digoxinb Anticonvulsantsc A ntiarryth micsd Theophyllinee Aminoglycoside antibioticsf Lithiumg Tricyclic antidepressants2. If individual variations are large - Antidepressants, Lithium3. Potentially toxic drugs used in presence of renal failure - Aminoglycoside antibiotic, vancomycin, cyclosporine4. In case of poisoning5. In case of failure of response without any apparent reason - Antimicrobials6. To check patient compliance - Psycho-pharmacological agents.o Drugs whose response is easily measurable eg. hvpoglycaemics metformin, antihypertensive, diuretics, oral anticoagulants and general anaesthetics, monitoring of plasma cone, is of no value. 