Heh, taking amitryptiline with it would be VERY unpredictable. Xanax works by just damping down the brain. It makes the sleep not work by preventing dreams while it is there and if it works, you won t feel entirely rested the next day. Ok, all anti-arrhythmics work by changing the activation of nerves. The pill doesn t have MUCH of a way to distinguish between the heart and the brain so it affects the nerves in the brain also. I said Much because it is far harder to get into the brain than the heart. And all anti-arrhythmics will have more effect on the heart than the brain. If a SLIGHTLY lower dose could be used or another drug, either might clear this up. Heh, Dofetilide is a marker for drugs that affect the heart. If you are making a new acne pill or new cold medicine you see if it looks like Dofetilide and if it does you throw it out. Amiodarone was for a long time the only anti-arrhythmic of this type in use but it is extraordinarily sticky. While not much gets into the head, it takes a month for it to get into you and if it did cause problems it takes a long time after it is stopped for it to stop working. There are simple rate control drugs that do not so much prevent AFIB as lower the heart rate. These don t get into the head as much (metoprolol) or don t have the same dream effects (verapamil).