WASHINGTON (AP) — Government scientists say they're seeing the emergence of a new class of deadly drugs built to mimic the potent prescription painkiller fentanyl. What you need to know:

___

DOZENS OF VARIANTS

The U.S. Drug Enforcement Administration's Special Testing and Research Laboratory has around 50 fentanyl-related compounds in its drugs database. Regulators are trying to catch up. China has blacklisted 19 fentanyl-related molecules and is now considering adding four more to its list of controlled substances, including the weapons-grade carfentanil .

___

EASY TO ORDER

It's easy to sourc...