Benzylfentanyl

Benzylfentanyl is a fentanyl analog that was initially listed as a Schedule I controlled substance in the United States in 1985 due to its structural similarity to fentanyl. It was removed from the list in 2010 after research demonstrated it has minimal opioid activity, with a binding affinity at the mu opioid receptor approximately 200 times weaker than fentanyl.