These substances have already killed more than 200 people on both sides of the Atlantic and are considered among the most dangerous designer drugs.

Fentanyl is the dangerous star in the world of opioids and drugs in general. But now, nitazene is also raising concerns.

Up to 50 times more potent than morphine, fentanyl is carving out an increasingly prominent place as a street drug due to its low cost and versatility in how it can be used: on its own, as a cutting agent for heroin, or mixed with cocaine and other stimulants in a speedball-style cocktail. Deaths in the United States now number in the tens of thousands each year, including famous names like Prince and Coolio. And while U.S. authorities are trying to curb the worst opioid epidemic in history (with 112,000 opioid overdose deaths recorded in 2023), a new danger is emerging on the horizon: nitazenes. This class of synthetic opioids is even 40 times more potent than fentanyl and has already caused more than 200 deaths in Europe and the U.S. since 2019, when it first appeared on the radar of international law enforcement.

In recent weeks, at the Congress of the Italian Society of Toxicology (SITOX) in Pavia, experts warned about the dangerous rise of nitazene abuse in Europe. According to experts, there are over 1,050 psychoactive substances that are difficult to detect with standard hospital tests, including nitazenes. Let’s take a closer look at what this is all about.

What is Nitazene?

Nitazenes are a class of synthetic opioids characterized by a peculiar molecular structure. They were discovered in the 1950s in the laboratories of an Austrian chemical company, CIBA Aktiengesellschaft, which synthesized several analogs of the parent molecule, etonitazene, with varying levels of affinity for opioid receptors and, therefore, differing potency. Their use as painkillers never took off, partly because they are highly addictive and can easily cause respiratory depression. Because of this, they remained largely forgotten for decades until they resurfaced in the illegal drug market.

The first reports date back to 2019 (following the inclusion of fentanyl and its derivatives on the United Nations’ Single Convention on Narcotic Drugs list), but it’s difficult to pinpoint exactly when interest in using them as drugs began, as identifying these molecules requires specific tests that are not routinely conducted in toxicological investigations. It is believed that several illegal laboratories have started synthesizing these substances in recent years, using historical chemical formulas found in pharmacology books and developing new ones, as their potency and the fact that they had been forgotten for decades by authorities make them ideal designer drugs. That is, substances that mimic the effects of well-known drugs (in this case, heroin), but attract less attention and have an undefined legal status, which facilitates their trade.

Effects and Dangers of Nitazenes

The effects of nitazenes are similar to all opioids: relaxation and a sense of euphoria. The side effects are also the same, including respiratory depression, which can lead to death in case of overdose. They cause addiction quickly and are substances that have been poorly studied in humans, as they have proven unpromising as medications. And it is precisely this lack of research that makes them dangerous. They have a high potency, which, however, varies significantly from one substance to another, and pharmacokinetic characteristics that remain relatively mysterious, making it difficult to predict how the body will respond to these substances. To date, they have caused around 200 confirmed deaths in the U.S. and Europe, but as their spread seems to have begun, there is a real risk of them becoming progressively more common in the coming years, possibly even rivaling fentanyl in prevalence. Many experts have been calling in recent months for greater efforts to monitor and combat the spread of nitazenes in Europe.