Yes, nicotine is an active ingredient in a drug, just as penicillin is an active ingredient. The active ingredient is almost always provided for use in various forms, such as injectable penicillin, pills, or capsules. The active ingredient will be combined with a number of inactive ingredients for administration. So inactive binders may be used to create a tablet (or capsule, which have a different set of inactive ingredients such as the gelatin), or specific liquids may be mixed containing the active ingredient for injection.
The FDA began regulating nicotine (no matter how obtained, whether extracted from tobacco or synthetically manufactured) back when nicotine delivery systems first were approved for smoking cessation. Those were the now familiar Nicorette line of gum, patches, oral inhalers, and even a nasal spray. These all required a prescription from a healthcare provider to obtain. In time, gum and patches were allowed to be sold over the counter, not requiring a prescription. The nasal spray version still requires a prescription in the US. These products are also available as generic drugs as the original patents have expired.
Covington & Burling is a well regarded firm. I do hope Nicopure understands the fees a firm like Covington will charge. Firms such as this are far from your local legal firm that prepares wills and handles divorces.
The first three claims argued, which boil down to the agency overreaching their authority and acting in an arbitrary manner creating an undue burden on the plaintiff/Nicopure/the vaping industry will keep the courts busy for quite a while. The First Amendment argument though will likely fall flat.
While enlightening and interesting............Still does not answer the actual Question.
Is Nicotine Defined as an Addictive Drug(in and of itself) By the FDA?
Yes it is used in Pharmaceuticals
Yes it is in Tobacco Products
Yes it Has been used in Pesticides
and Yes, we use it in Vaping liquids
But is it an Active ingredient or a Classified Drug?
I Understand it is Regulated in inclusion in Pharmaceutical applications, and in Tobacco is Claimed to Be Highly Addictive, but it does not seem to Fall under Controlled Drug Classification and therefor would be a Questionable Active Ingredient, Not an Addictive Drug.
I would say the Addictive Potential of Nicotine is 90% Perception(Smokers are addicted arguments) and 10% Science(Nicotine without Tobacco)
Meanwhile - Thank you to Nicopure for not a moments Delay in taking action against the FDA!