No surprise to anyone here that we are in the midst of a deadly opioid epidemic in the U.S. One aspect of this can be described as chemical warfare, where changing a molecule enables a formulation to temporarily be "legal". This molecular battle is also part of the emerging "synthetics" problem with so-called bath salts and synthetic marijuana.
The National Emerging Threats Initiative of the HIDTA program has developed a free app for Apple and Android devices on key emergent drugs. You can download it by searching NETI HIDTA on the app stores. Feel free to share it with family and neighbors as well as with interested LE partners.