Essential to your discussion should be various examples of the classical exploitation film (e.g., 'Reefer Madness' and the like), as these early drug films not only strongly reflect the shaping of drug control policy in the U.S., but also to some extent helped shape and reinforce said policy. Eric Schaefer's book "Bold! Daring! Shocking! True!" on the classical exploitation film is packed with useful history of drug scares and early anti-drug films.
The post-classical exploitation film deserves consideration as well, such as AIP productions like 'The Trip' and others.
David Church