A recent report warned physicians to look out for cases that appear to be heroin overdoses but are actually linked to the quasi-legal drug acetyl fentanyl.

The drug is an opiate that is mixed into other street drugs and marketed as heroin, the American College of Emergency Physicians (ACEP) reported. 

"What's frightening about this emerging street drug is that users themselves may not be aware that they are ingesting it," said lead study author John Stogner, Ph.D. of the Department of Criminal Justice and Criminology at the University of North Carolina at Charlotte, N.C.  "A patient may report heroin use and have symptoms consistent with heroin overdose, but an emergency physician may find that the standard dose of antidote (naloxone) doesn't work.  Larger or additional doses are necessary when acetyl fentanyl is responsible.  It's never good to lose time between overdose and treatment."

The dangerous opiate currently has no recognized medical use and is 15 times stronger than heroin; it is usually injected intravenously. It's high potency makes it more likely to cause serious health consequences in consumers. 

Acetyl fentanyl is not legally regulated but is considered to be an analogue of fentanyl (a medical opiate), causing it to exist in a "legal gray area" in which it is illicit for human consumption but technically legal when labeled "not for human consumption."

"Clever and well-informed drug distribution networks will likely take advantage of the legal loophole and profit by replacing or cutting a highly-regulated drug with this less regulated one," said Dr. Stogner.   "One of the many downsides of illegal drugs is you just can't trust your drug dealer. The trend of adulterants being worked into street drugs to make them more potent is dangerous.  The significant potential for overdose of acetyl fentanyl necessitates more medical research and policy reform."

The findings were reported in a recent edition of Annals of Emergency Medicine.