My step mom is management at wal mart, and is making me go through the application process. Usually I would be very happy a job was given to me so easily, but I must pass a drug test. The hiring process is 1 month long. I am a 18 year old 115lbs female who smokes everyday. What dosage should I be looking at of niacin to pass a drug test in 3-4 weeks and clean out my system? I am also open to other techniques for passing drug tests in 3-4 weeks or less maybe! I want to be absolutely sure I'm clean before I take the drug test. Thank you