I found this
How Long Methadone Stays in Your System?
The detection window of any drug depends upon age, weight, mind set, and health condition of the examinee. Apart from that, the dosage of the drug, its quality, and period and potency play an important role during the drug test. Urine test reveals positive result for 1-7 days. The half-life of drug is just 24-36 hours, and it may remain in your system from 7 hours to 52 hours. Half-life refers to the time taken to eliminate half of the drug’s effect; A drug takes 4-5 half lives to get expelled out of your system completely. It is always better for the person to stop using methadone two weeks prior to suboxone treatment.
http://howto.dcrdetox.com/how-long-does-methadone-stay-in-your-systemrom this website
You have gotten excellent advice. I just want to add that when your in pain management you should always take ONLY what is prescibed. talk to your daughter and explain that she can/will be dismissed for this and it will be very difficult to find a doctor to treat her after this is in her file/records.
So many people do not get the help they need because doctors are very disturbed by things such as this. Your daughter is lucky to have found a doctor willing to treat her pain in these times and as I said if she has a urine test that includes other drugs besides what she is prescibed she will have a very hard time if at all finding a new doctor to treat her.
Your daughter is welcome to join our community too :)