I'm pretty sure it does show up if opiads are checked for, it's made from the same synthetic opiate as hydro and oxy. Opiads aren't always looked for in standard pre-emp drug screens, but that depends on the number of panels in their test. Most opiads will test positive only up to 5 days, Methadone will for 7 days. Most pre-emp tests just look for the illicit drugs, including codeine and >>>>>>.
2 different times i took pre employment drug tests with at least 100 mg of hydrocodone taken the morning of the tests and passed both of them. A lot of companies dont check for that, but some do. Also some companies will put your name on a list if you apply for a job with them a fail a drug test, this is then sold to other companies. Some of the larger companies do this..and as soon as you turn in your application they check your name against that list. Please let me know if that didnt make sense.
Anyway, it would be best to wait...but if its unavoidable there's a good chance they wont even test for it.
Again, this is all I know...There is a lot more info out there!