Your topical lidocaine jelly is not likely to make your fiance fail his drug test for methadone.
I am sorry to hear that he is being incarcerated due to a failed drug test. However, before the testing, they usually will ask you what medications you are currently taking, so they can take that into account with the results. Please make sure that they have a complete list of his current medications, including prescription and over-the-counter meds, vitamins and herbal supplement.
Good luck and do take care.
If you need more information, please go to:
1. Drugs of Abuse - National Institute on Drug Abuse
2. Strattera (atomoxetine) - Daily Med
3. What is Attention Deficit Hyperactivity Disorder (ADHD, ADD)? - National Institute of Mental Health