The FDA does in fact regulate electronic nicotine delivery systems, such as e-cigarettes, hookah pens, and vapes [1]. I think that e-cigarettes are different from normal cigarettes in terms of regulation because, with e-cigarettes its tobacco-less, and it contains just some of the chemicals as normal cigarettes [2]. With normal cigarettes, it contains tobacco along with a numerous amount of chemicals that can be harmful [2]. Based on this, normal cigarettes seem to be more debatable in terms of how it should be regulated. I do think that its possible for e-cigarettes to be used as a drug delivery system, but only for drugs that can be delivered successfully in that way. This would definitely require some clinical testing to make sure that the drugs are successfully delivered to its target area. Even though the e-cigarette is already a known product, I do think that it would be considered a class 3 device since it would be used for drug delivery, which is different from its initial purpose.

[1] https://www.fda.gov/TobaccoProducts/Labeling/ProductsIngredientsComponents/ucm456610.htm

[2] http://www.stopcancerfund.org/uncategorized/are-e-cigarettes-safer-than-regular-cigarettes/