The FDA regulates and registers drug manufacturers, wholesellers, distributors and represenatives. This allows them to posses, transport and distribute(as samples to MD's) and sell scheduled drugs.
And that points out the catch-22 of taking advantage of the FDA's 'humanitarian importation' guidelines. It may be legal to import but possession(of a scheduled substance without a valid perscription) is still like a class 4 or 5 felony.
But most LE realizes that if they go after a disabled person with a panic disorder for possession of XANAX, most judges would just laugh them out of court and ask why they were wasting taxpayer funds.