The highest law in the land is the constitution. The constitution can not be amended via treaty. If the drug control laws you are talking about involve drugs crossing borders (state or national) then they would be constitutional. Anything else should fall to the states.
“should”
Perhaps so.
In fact however, those three constitutionally ratified treaties have been legally implemented and enforced.
In reality, if you want to legalize marijuana in the USA, those treaties need to be modified or withdrawn from.