I don't know. I am not very trusting. I would think that when they looked at qualifications for disability payments they would question the reason why a person was fired or suspended. If a person was working in a job where you could not take performance affecting medication, you probably wouldn't get much support. You might even have to fight the employer for wrongful dismissal to prove that they terminated your employment with insufficient reason.
They can't just fire them for using a prescribed medication. If it's something that affects their work, then they may be laid off until they are no longer on the medicine (like the NASCAR driver was). I doubt they could actually apply for disability unless it's actually something that would prevent them from getting -any- kind of job and was a permanent predicament.
I do not think you could apply for disability because of it. They would probably expect you to go find a job that didn't have such risks. Unfortunately that's because our economy really sucks right now. Otherwise there would be a lot more people on disability.