Drug:
b : a substance used as a medication or in the preparation of medication c according to the Food, Drug, and Cosmetic Act (1) : a substance recognized in an official pharmacopoeia or formulary (2) : a substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease (3) : a substance other than food intended to affect the structure or function of the body (4) : a substance intended for use as a component of a medicine but not a device or a component, part, or accessory of a device
2 : a commodity that is not salable or for which there is no demand -- used in the phrase drug on the market
3 : something and often an illegal substance that causes addiction, habituation, or a marked change in consciousness
seems to fit the bill to me.