structure activity relationships

The insanity of trying to control overdose deaths by banning certain drugs became evident years ago with fentanyl. Yet we now have a new monster on the street called Tranq and some people think that making it illegal will get rid of it. Simple chemistry guarantees that this plan will fail. Here's why.
Remember when the term "designer drug" was used in the 1980s? One of the drugs included in that group was called 3-methylfentanyl, aka, mefentanyl. Although not widely used, it killed groups of people who tried it. Fast forward 4 decades and it's now one of the 30 fentanyl analogs that are responsible for the fentanyl crisis. And it's also one of the worst. What a difference a methyl group can make.