Outlawed is an interesting term...
Insulin is "outlawed" in that insulin dependent diabetics are unable to obtain a medical certificate without a (nearly impossible to obtain) waiver (49 CFR 391.41(b)(3)). As would be meds like say, phenobarbital or other anti-seizure meds, since seizure-prone epileptics are also unable to obtain a medical card (49 CFR 391.41(b)(8)).
Then again, would you REALLY WANT SOMEONE operating 80,000 lbs. of "rolling death" that was prone to seizures, blackouts or insulin shock episodes of passing out?
OTOH - narcotic pain medication (with a prescription of course) is permitted, with a supporting letter from your physician stating that the use of the medication will not have a negative effect on your ability to operate a CMV (49 CFR 391.41(b)(12)). Methadone is NOT an allowed exception. Now I know folks that are on MASSIVE DOSES of narcotic pain meds, for chronic pain management - that aren't even slightly buzzed from them - and work, drive and have productive lives that they otherwise could not have due to pain. The reg cited above, points to 21 CFR 1308.II as the "list" of prohibited drugs.
http://edocket.access.gpo.gov/cfr_20...cfr1308.11.pdf
The point is, we really don't need junkies, meth heads, crack heads, active alcoholics/addicts or anyone else who may be impaired by prescribed, over-the-counter, or street purchased operating a rig out there.