Yeah, "designer drugs" -- the products someone trying to make a drug that works on the same systems but is different enough in structure from anything on a Cont

Yeah, "designer drugs" -- the products someone trying to make a drug that works on the same systems but is different enough in structure from anything on a Controlled Substances list are bad news. The problem lies in the fact that many drugs with long histories of human use (opium, marijuana) have long histories of human use, and so they've been tested extensively and are known not to produce horrid adverse effects. Trying to replicate a compound that has been tested for efficacy and safety over literal millenia (and not being allowed to just change tiny things on the molecule) is not something that is likely to give results close to the original. Ironically, the obverse task -- trying to create a molecule that acts on similar neurobiological targets as an illegal drug but doesnt get people high or look like a molecule from an illegal drug -- is similarly fraught. A flagrant example is BIA 10-2474, an experimental drug meant to target the endocannabinoid system in a roundabout way -- not by directly activating receptors, but by inhibiting an enzyme that degrades endogenous chemicals that activate endocannabinoid receptors -- which would have similar effects as directly activating those receptors. A trial of it killed one person and irreversibly neurologically damaged a few others. We criminalise drugs at deep costs to research and medecine (I haven't even gotten into the use of MDMA in psychotherapy or ketamine for depression), and regardless on what side of the law they work on, it is a very difficult task for chemists to try to imitate drugs that have been with humanity for millenia when they aren't allowed to make molecules that look like blacklisted ones.