I am not a doctor, but I would think you DON"T want to take methadone for bi-polar. If you are still visiting this site, feel free to message me and I can go over things that have helped me (being I was diagnosed bi-polar manic depressive).
He is on seroquel currently. What I read is that the antidepressant can actually negate some of the effects of the seroquel. As I said, I am desparate at the moment because of his threats.
Still in the early stages of research so I am not sure if a psychiatrist would consider it but there are a wide variety of mood stabilizers both FDA accepted for this use or FDA approved medications used off label as mood stabilizers:
http://www.psycheducation.org/depression/meds/moodstabilizers.htm