The fentanyl patch is prescribed by a physician. It is a synthetic morphine, and the patch method of delivery keeps it in your system constantly. It comes in a variety of strengths. People use anywhere from 25 micrograms to 400 micrograms, and change the patch every 2 or 3 days. If your husband did not get relief from methadone, he probably wasn't given a high enough dose. Some doctors are uninformed about prescribing pain meds. You may need to go to a pain specialist.