Do the words of the Ninth Amendment mean anything to you?
9th Amend...The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.
As long as you're not headed down the path of arguing that bestiality and polygamy are protected rights, I think you are now on much firmer ground. I think that the argument against Federal laws regulating intrastate drug trafficking and use are logical and strong. In my estimation it might lead to a requirement to get a specific amendment to allow for the the FDA. Although foreign trafficking is still clearly regulatable in my opinion.