<prompt> American anesthetic association says that clopidogrel should be withheld how many days before surgery?1 day1 week3 weeks4 weeks  <response>: 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. 