What makes heroin’s synthetic cousin, fentanyl, one of the deadliest drugs in the world?

What makes heroin’s synthetic cousin, fentanyl, one of the deadliest drugs in the world?

“Dealers are lacing cocaine and heroin with fentanyl, and young adults are dying in significant numbers. It is an epidemic. Horrific,” says a registered nurse in New Zealand. Indeed, while there has been a downward trend in deaths from prescription opioids alone, overdose deaths from fentanyl have risen dramatically, up 540 percent in three years.

Fentanyl is a synthetic opioid painkiller, prescribed to treat severe pain. It is a cousin to heroin, but much deadlier because it is much stronger—50 times more potent than heroin, according to the Centers for Disease Control and Prevention. The photo to the left shows a lethal dose of heroin, at about 30 milligrams, compared to fentanyl, a dose of only 3 milligrams. In fact, rescuers responding to overdose calls have to be careful—just touching it or inhaling it can be deadly.

Fentanyl owes its potency over heroin to differences in chemical structure. Both chemicals bind to the “mu opioid receptor” in the brain. But fentanyl gets there faster than heroin because it more easily passes through the fat in the brain. It also grabs onto the receptor so tightly that it doesn’t take much to trigger the opioid effects in the body.

As fentanyl is a fine powder, it is easy to mix into other drugs. It looks identical to heroin, so users, injecting heroin laced with fentanyl, won’t know they’re injecting a lethal dose until it’s too late.