Ans is 'b' i.e. 1 week Preoperative modifications of pre-existing drugsDrugs which can be stoppedDrugs which can be continued till the day of surgery* Conventional dose aspirin & clopidogrel (antiplatelets)-1 week before surgery* Oral anticoagulants - 4 days before & switch to heparin, which is stopped 12 hours prior to surgery* Oral hypoglycemic (metformin) - 48 hours before surgery and switch to insulin* AT-II antagonists (losartan, valsarton) - 1 day prior* Lithium - 48-72 hours before surgery* MAO inhibitors - 3 weeks before surgery* Antianginal (except aspirin)* Antiepileptics* Antihypertensives (except AT-II antagoists)* Levodopa* Digitalis* TCAs* Low dose aspirinNote: Antiplatelet drugs like clopidogrel and conventional dose of aspirin should be stopped 7 days prior to surgery. But low dose aspirin can be continued till the day of surgery.