In my case, I have a very understanding supervisor. Some of my drugs are listed with the company MD - for instance, right now, I'm on Vicodin fairly regularly (which is why I happen to be up this early - needed a dose) - I have it on record so that if I get pulled on a "random drug test " I don't have a problem.

BTW I've never heard of the company actually DOING a test, but they have reserved the right to do so