You are aware of the hundreds of drugs that were once prescrition only and are now OTC?
All drugs should be legal and dispensed from a quality-regulated source aka pharmacy. The black market has injured more than actual use or misuse of black-market drugs.
Only antibiotics should be restricted as they pose a risk to non-users due to emergence of superbugs. Othwerwise we should be capable of making decisions for ourselves. If we are too stupid to make decisions for ourselves how are we capable of making decisions for others?
I truly believe the libertarian idea of a victimless crime is faulty as a persons actions effect everyone around them and society as a whole. If you could pick up a bottle of Vallium along with some Oxycodone on your trip to the grocery store we would have 1000s more accidental deaths every year.