It is a very unwise idea to use medicine that is past its expiration date, or old medicine that you have been taken off. Someone I know recently took an expired pill from a blood-pressure prescription that he was taken off of a few years back (he had run out of the pill he is currently on and wanted to wait to buy more, and he hadn't gotten around to throwing the remainder of his old prescritpion away). He wound up fainting and breaking an ankle, and it could have been very serious had the ambulance not arrived as soon as it did.
In any case, the lesson here is, when they say not to take expired medicine and not to take pills from prescription you have been taken off of, there is a good reason. It isn't just smoke. They really mean it.
That is all.