Without going too far into questionable territory, and noting that I have a family member who is a forensic toxicologist:
You can buy these, from China, with various, "factory markings." E.g., if you wanted to, you could grind up D-Con, bleach it a bit, and press it back into a tablet marked as Oxycontin, and it would totally pass visual inspection. Fentanyl/components is/are cheap and readily available online as well (China). People work with it every day, in illicit cook houses and like any other hazardous activity, you have to be careful. Powdered form is not the same as patches which is not the same as IV/IM solution, so within certain limits, it isn't like it will spontaneously transdermally absorb, unless it's formulated in a carrier designed to do so.