I'm no doctor but I don't think a drug can change thoughts. The way we think is part of who we are, our attitude, and personality, faulty thoughts may be in response to depression or stress in which case the drug may help with our response, but if you are a glass half empty person it won't change that. Drugs don't cure our problems, they simply make it a little easier to deal with while we work on it typically in therapy. Drugs alone aren't very effective. My suggestion is to learn mindfulness to help you identify when you are beginning to have these thoughts. You can try ability if your doctor thinks it will help you, but don't give up on yourself and your ability to effect your outlook on life.