Well, then you actually have the wrong argument, as far as I am concerned, since we *don't* actually have a 'drug prohibition' in effect.
We have *controls* in effect. Drugs are availble, when needed and when necessary. It will take a physicians signature to get the stronger 'drugs', but such simple drugs as aspirin and cold/flu aids like NyQuil *are* freely availble over the counter without any 'prohibition' in effect ...
Saying we don't have a drug prohibition in effect, because some drugs are legal or even OTC, is like saying the Nazis weren't racist, because there were some races (for example, Aryans) who were not sent to the gas chambers as a matter of national policy.
Obviously, some drugs are prohibited, and if any are, then there is a prohibition in effect, specifically pertaining to those drugs.
Duh.