Black sword,
I have no need to ask a doctor, I have seen the readings from Lab anaylsis, I have been in court when people have been convicted on Urine test evidence, and while our polititions may not be the sharpest tools in the box, they don't get that sort of thing wrong. Besides I am sure that every medical expert in creation has been wheeled in to try to disporve it, and so far with 100% failier rate.
The fact remains that urine, like breath refelcts the content of alcohol in your blood. If you don't want to take my word for it, please feel fee to test your theory. But I would suggest you get some medical advice first.
As for the drugs side of it, I'll reiterate what I said. Many drugs cause side effects, like Night Nurse caused some people to feel sleepy or drousey. Hence the warning about if the drug affects you don't drive, you see it on many drugs. Its also why the CAA don't let ATCO's or Pilots operate when taking anti depressents and other prescription drugs. Those are the lower end of the effects, obviously if you are taking LSD the effects are somewhat worse....
I hope that answers your point, if not please clarrify and I'll try again.