Butanamide, N-phenyl-N-[1-(2-phenylethyl)-4-piperidinyl]-
Butyrfentanyl or butyrylfentanyl (not to be confused with 3-methylfentanyl) is a potent short-acting synthetic opioid analgesic drug. It is an analog of [fentanyl] with roughly 1/30 the potency. Butyrfentanyl was first synthesized in 1961 by Janssen Pharmaceuticals as a new opioid analgesic.  Butyrfentanyl has no current legitimate clinical applications, but anecdotal reports indicate it may occasionally be surfacing on the grey-market as a recreational drug. This compound is a schedule I controlled substance in the USA because it is a positional isomer of 3-Methylfentanyl.  The DEA in the United States has confirmed at least 40 fatalities involving butyrfentanyl before May 2016.