When you take any kind of psych medication it increases the sensitivity to alcohol. When I drink (even if its just one beer) I skip mess and prepare myself for some destabilization. Its sad because I like drinking but the side effects keep me from doing it for the most part.

If you think you are becoming manic you can ask your doctor for a temporary prn of something and discontinue it after 2-3 weeks. I do this with lithium and it works for me so long as I catch it early enough. Another thing that helps is trying something to regulate sleep. Stabilizing sleep can help.