Iso:
The New Synthetic Opioid
That Is Causing Overdose Deaths



Experts say a new synthetic opioid called “iso” is causing
an increasing number of overdose deaths in the United States
and is difficult to detect on standard opioid tests.
Getty Images


A new synthetic opioid known as “iso”
is causing an increasing number of
opioid overdose deaths.

Isotonitazene is a synthetic version
of etonitazene.

Experts say it’s rapidly becoming more
popular in the illegal drug market in
the United States.

They add that the drug is difficult to
detect on standard opioid tests.


An addictive drug that — like fentanyl — is much more powerful than morphine
is causing an increasing amount of overdose deaths across the United States.

Isotonitazene, commonly referred to as “iso,” is a synthetic version of etonitazene,
an opioid that’s been around since 1957.

One report says the drug is causing about 40 to 50 deaths a month in the United States.
That’s up from about six per month last summer.

“Etonitazene is 1,000 times more powerful than morphine,” Dr. Yili Huang, the
director of the pain management center at Northwell Health’s Phelps Hospital in
New York, told Healthline. “Although isotonitazene is less potent than etonitazene
that it’s derived from, it’s still more potent than fentanyl.”

“The best way to think about it is that isotonitazene is a stronger cousin of fentanyl
and therefore likely even more dangerous,” Huang added.

According to the Centers for Disease Control (CDC)Trusted Source, more than
31,000 people died in the United States in 2018 from overdosing on synthetic
opioids like fentanyl, which is typically used to treat pain in cases of advanced cancer.

Other opioids, such as oxycodone, hydrocodone, codeine, and morphine are used
legally to treat pain and can be addictive. Heroin is also considered an opioid
and is illegal.



What is iso?


Iso comes from China, Huang said, and is designed to mimic the effects of etonitazene,
thereby avoiding classification in the United States until recently.

Etonitazene is classified as a schedule I controlled substance by the Drug Enforcement
Administration (DEA), meaning it has high abuse potential.

Huang said there’s no current accepted medical use for etonitazene or iso in the United States.
Part of the uptick in iso’s use is manufacturers responding to nations cracking down on
fentanyl. China banned fentanyl and its derivatives in 2019.

“It certainly could be the new fentanyl,” Dr. Jill Thompson, the medical director at
Harmony Recovery Center and Midwood Addiction Treatment in North Carolina, told Healthline.
“Every few years, a new substance becomes popular for one of several reasons and
it becomes the drug of choice.”

“Just as fentanyl has proven to be a highly addictive and dangerous substance, iso may
actually surpass it in use and overdose rates over the next few years,” Thompson said.
“Iso can be mixed with other substances, pressed into tablets, and is available in several forms.”



An increase in use



Part of iso’s potential for a jump in overdose deaths is that U.S. drug laws have had
trouble keeping up.

It wasn’t until last week that DEA officials announced they were labeling isotonitazene
as a schedule I drug.

“It has not been explicitly illegal and therefore sold online,” said Thompson.
“It was being sold on the dark web, largely manufactured in China. Initially,
it was most commonly found in Belgium, Canada, and Germany. Last year, it
was showing up in Illinois, Iowa, Ohio, and Kentucky. Earlier this year, a drug raid
seized 1,900 tablets of iso in Halifax (Canada).”

“Many experts in the field believe it will replace heroin quickly and may even surpass
fentanyl use in the next few years,” she added.

Because iso is new, it’s difficult to get a clear picture on its use, said Dr. Steven Powell,
the chief medical officer of PursueCare, which specializes in treating opioid addiction.

“Because data is just emerging, past overdoses attributable to it are unclear, and
future projections are hard to make,” Powell told Healthline. “As we learn more and
catch up to what is actually out there, we will learn that iso is one of several derivatives
that has played a past role in death, and hopefully start to project how it might contribute
to overall overdose rates in the bigger picture of all synthetic opioids.”

“Our understanding is that it can be more potent than fentanyl, extremely potent,
but it hasn’t been extensively studied to know the toxicity,” he added.



Difficult to detect


Another problem is that in this stage of iso’s development, it’s difficult to detect in tests.

“Like other designer or novel psychoactive substances, iso is not detected in a standard
opiate drug test,” Thompson said. “Special drug screens are currently being developed
in order to detect the substance on a routine (drug screen).”

“Unique problems associated with iso is the lack of familiarity among law enforcement
and even the medical community,” Thompson said. “If the ER does not suspect an iso
overdose and opiate testing is negative, the correct diagnosis may be missed and
potentially overlooked with deadly consequences.”

Naloxone is commonly used to treat opioid overdoses. Opinions vary as to its
effectiveness on iso.

“Treatment of iso overdose is more difficult than that of other opiates,” Thompson said.
“Reportedly, Narcan (a brand of naloxone) is effective but must be used in higher doses
and perhaps multiple times.”

Huang said it’s important to note that naloxone only temporarily deals with the problem.

“Healthcare providers need to remain vigilant,” Huang said. “The development of this
drug highlights a deeper concern. New drugs will continue to emerge as long as there
is demand. We must continue to use resources to curb this demand with education
surrounding judicious opioid use and addiction treatment.”