sentences:  Betahydroxythiofentanyl
  
  Betahydroxythiofentanyl (β-hydroxythiofentanyl) is an opioid analgesic that is an analogue of fentanyl.Betahydroxythiofentanyl was sold briefly on the black market from around 1985, before the introduction of the Federal Analog Act in 1986 which for the first time attempted to control entire families of drugs based on their structural similarity rather than scheduling each drug individually as they appeared.