Can i take 2mg of sedoxil at once before doing an operation with local anasthetic, as i am very afaraid, usually when i go to dentist or for an injection i just take 1mg but i don't think this time will be enough to control my anxiety?

You should not take any more medication than what is prescribed by your doctor who knows your situation best. If you are having a procedure in an operating room, they can give you some medicine to relax you as well as the local anesthetic. Let the anesthesiologist know that is your preference and this can be done while you are carefully monitored. Good luck!

Discuss your anxiety w your Dentist well before your appointment. Doubling your anti-anxiety meds without your prescribing doctor's approval may be unwise/unsafe, especially if you need to drive. If your med worked in the past, there is no rational reason why it will not work this time. And perhaps it's time to see a mental health professional to address your unfounded fears.