Hi ToyL
John gives good advice. I would add that there is no evidence that carb/lev stops working. Our ability to store and use it diminishes which is why you are finding the dose doesn't last as long. The answer usually given is to take less more frequently. Where you diagnosed in 1996 or was that when you first noted symptoms? You say you can't tolerate rasagiline. What was your reaction to it? You may find you can take it now.