Isotonitazene: A Drug on the Rise in the U.S.
By: Lakeview Health Staff
Published: November 15, 2023

Drug trends in the United States continue to change at an alarming rate. Every day, new opioids like isotonitazene are slowly working their way into the U.S. drug supply, putting substance users at elevated risk of overdose and opioid addiction.

What Is an ISO Drug?

Isotonitazene is commonly referred to as “ISO.” It is a synthetic opioid that is more than 500 times more potent than morphine, according to the World Health Organization. It is 5 times more powerful than fentanyl.

In its pure form, ISO is typically found as a white or off-white powder. But more commonly, ISO is mixed into other drugs or contained inside “pressed pills” meant to resemble prescription medications such as oxycodone or Dilaudid.

Origin of Isotonitazene

ISO belongs to a class of drugs known as nitazenes. Nitazenes are potent synthetic opioids, originally developed by Swiss researchers in 1957 looking for new medications that could provide pain relief without the addictive potential associated with traditional painkillers.

When these drugs were finally synthesized, the researchers determined that they were too potent and too addictive to bring to market. For the next 60 years or so, these drugs went off the map, not being used in clinical applications or seen in the illicit drug market. 

But in 2019, ISO began to be identified in toxicology screens performed on people who had died from expected opioid overdose. Other nitazenes, such as etonitazene and metonitazene, have been detected in illicit drug supplies as well.

At the time, isotonitazene was an unscheduled substance, meaning it was legal to purchase. However, as authorities began to recognize the growing rates of isotonitazene use, the DEA moved rapidly to make it a Schedule I Controlled Substance in mid-2020. It is now illegal to purchase or produce.

Chemical Composition

The exact chemical class of drugs that isotonitazene belongs to is known as nitrobenzimidazoles. These drugs are structurally different from other synthetic opioids, such as fentanyl and its analogs.

As a synthetic opioid, isotonitazene is chemically synthesized in laboratories rather than derived from natural sources. According to information from the United States Drug Enforcement Administration, the primary source of drugs such as isotonitazene is illicit laboratories in China, which ship synthesized chemicals to drug suppliers in the United States.

How Isotonitazene Is Different From Other Opioids

The primary difference between isotonitazene and other opioid drugs is in its potency. As described above, isotonitazene is one of the most potent opioids on the illicit drug market today, being 500 times stronger than morphine and five times stronger than fentanyl.

Rates of ISO Use

The exact rates of ISO use in the United States are unknown, and its presence on the illicit drug market was only detected for the first time in 2019. Emerging opioids are often difficult to track and detect for several reasons, including:

  • Limited ability to test illicit drugs for isotonitazene
  • Limited knowledge about isotonitazene among substance-using populations
  • Substance users are often unaware that the drugs they are taking contain isotonitazene

In an evaluation of isotonitazene published in March of 2023, the DEA reported 726 cases where isotonitazene was identified by forensic drug laboratories. This includes data from federal, state, and local laboratories and includes both isotonitazene alone and in combination with other drugs.

The best way to determine rates of isotonitazene use is through forensic toxicology reports. According to toxicology researchers, isotonitazene was identified in a growing number of toxicology reports between the end of 2019 and the middle of 2020. 

However, following the classification of isotonitazene as a Schedule I Controlled Substance in 2020, the number of toxicology reports identifying isotonitazene began to fall.

Similar data from 2022 onward is not currently available, though there are continuing reports of drug seizures containing isotonitazene. Additionally, an analog of isotonitazene — known as N-desethyl isotonitazene — is increasingly being identified as another emerging synthetic opioid of concern.

Risks of ISO Use

The primary risks of isotonitazene break down into three distinct categories:

1. Addictive Potential

Like most other opioid drugs, isotonitazene has a high potential for addiction and dependence. Isotonitazene functions as a full opioid agonist, meaning the drug latches on to opioid receptors throughout the brain and body, causing the well-known effects of euphoria, relaxation, slowed breathing, and pain relief.

But when opioids like isotonitazene are taken repeatedly, these receptors become dependent upon the drug’s effects. When the drugs wear off, people can feel intense physical and mental withdrawal, resulting in symptoms like:

  • Sweats
  • Tremor
  • Anxiety
  • Nausea and vomiting
  • Invasive drug cravings
  • Restlessness
  • Runny nose
  • Flu-like symptoms

These withdrawal symptoms alone are enough to drive many people back to substance use rather than live with the intensely uncomfortable experience they have without them.

But addiction is about far more than physical symptoms alone, as people can become psychologically reliant on opioids for any number of reasons.

2. Overdose

The largest risk for isotonitazene use is the potential for drug overdose. With such incredibly high potency, even a tiny amount of isotonitazene can result in rapid drug overdose and death — particularly in people with low tolerance for opioids.

But unlike the synthetic opioid fentanyl, which is largely responsible for the dramatic increase in drug overdose deaths over the last several years, there are currently no available test kits that can detect the presence of isotonitazene in illicit drugs. 

This means that even if people are taking the added precaution of testing their substances before use, they may be unaware of the drugs they are ingesting. Thankfully, isotonitazene does seem to respond to the opioid overdose medication naloxone

3. Drug Contamination

Drug contamination of isotonitazene can occur in one of two ways:

  1. Isotonitazene is pressed into pills resembling prescription drugs or used to adulterate illicit drugs
  2. Accidental contamination of other drugs with isotonitazene

The first of these two pathways has been reported on by the DEA. In 2020, Canadian law enforcement found several pills resembling the prescription opioid Dilaudid, which were found to contain isotonitazene. This parallels the trends seen in fentanyl distribution, where synthetic opioids are pressed into pills meant to look like prescription painkillers.

The second pathway has not yet been observed with isotonitazene but carries a real risk if the drug continues to grow in popularity. Similar to fentanyl, isotonitazene is typically found in powder form and is extremely potent. Just a few grains of this powder contaminating other drugs can lead to overdose, as has been seen frequently with the drug fentanyl.

To make matters worse, isotonitazene dealers do not follow laboratory cross-contamination procedures when creating the substance. Shared surfaces or unsanitary conditions where illicit drugs are being prepared can easily lead to cross-contamination of these chemicals, leading to accidental contamination and potential overdose.

Recovery From Opioid Use Disorders

The changing landscape of opioid use is a continuing cause of concern in the United States. With the proliferation of powerful synthetic opioids, such as fentanyl and isotonitazene, rates of opioid overdose have spiked dramatically, and the risk to substance users has never been higher.

But if you or a loved one is struggling with an opioid addiction, there are evidence-based methods that can help you overcome your addiction and achieve a lasting recovery. These treatments work regardless of the specific opioid you use and can provide tangible relief from physical withdrawal, actionable strategies to resist relapse, and long-lasting support for a life in recovery.

When you’re ready to get started with opioid addiction treatment, call the team at Lakeview Health by dialing 866-704-7692. Our team can help explain our comprehensive suite of recovery services, help you find the treatment that best suits your needs, and will be there to support you along every step of your recovery journey.

Overcoming addiction is hard, but it is possible. Take the first steps toward your recovery by calling Lakeview Health today, and start the journey to a better, healthier, more rewarding life.