Is a “vape” a drug delivery system and what besides nicotine might be delivered by it?
There are a lot of different forms of ¨vapes¨, but the main kind is designed to deliver nicotine in a safer and more effective way than cigarettes (or other nicotine delivery methods). They contain a thick liquid called e-juice, which is a mixture of propylene glycol and/or vegetable glycol, as well as flavoring and nicotine (Among others depending on the situation.) You can also suspend other drugs into a PG solution, really, anything that can be smoked will also be vape-able.

Reference: https://www.quora.com/Is-a-vape-a-drug-delivery-system-and-what-besides-nicotine-might-be-delivered-by-it