My daughter took .25mg of Xanax late Friday night. She has a Rx for Lorazepam but didn't have it with her. She has a urine drug screen tomorrow morning as she is on probation. I tested her last evening with a First Check home test and it showed negative with a faint line. How long would this normally take to pass thru the system and become undetectable. She is 5'1" and approx 135 pounds.