Following a spate of overdose deaths recorded earlier this year in NSW, authorities are raising concerns over the emergence of a new, deadly drug infecting illicit drugs such as cocaine and heroin.
Nitazenes are a group of compounds developed in the 1950s as opioid analgesics, but they were never approved to market due to their high potency, which can be hundreds to thousands of times more potent than morphine and other opioids, and 10 times more potent than fentanyl.
Concerningly, nitazenes have been found represented as other opioids such as heroin, oxycodone and in non-opioid substances being sold as ketamine, MDMA, cocaine, alprazolam and 3C-P, raising the spectre of overdose for unsuspecting users.
According to Professor Giustino Varrassi, an expert in pain management at the Paolo Procacci Foundation in Rome, who authored a paper on the emergence of nitazenes last year, several nitazenes, including ‘designer analogs,’ have been detected in the illicit drug supply implicated in overdose mortality, primarily due to their exceptionally high potency.
“In the street drug supply, nitazenes are often found mixed with fentanyl or other agents but their presence is not always disclosed to drug buyers, who may not even be familiar with nitazenes,” he said.
“These drugs pose a particular challenge since there is little experience in how to reverse a nitazene overdose or potential drug-drug or drug-alcohol interactions.
“Public health efforts are needed to better inform street drug consumers, first responders, healthcare professionals, and the public about these “new old drugs” that are infiltrating the recreational drug supply.”
There have been several detections in Australia, with 17 cases recorded by the NSW Poisons Information service and 18 reported by Victorian emergency departments.
Sentinel monitoring of ED presentations through Emerging Drug Network of Australia has detected 22 nitazene cases (involving protonitazene, metonitazene, isotonitazene and etonitazepyne) in Queensland, SA, Victoria and WA.
Wastewater analysis has not yet detected nitazenes, though monitoring for new psychoactive substances is limited, and little coronial data is currently publicly available, with only three overdose deaths involving nitazenes reported in Victoria in 2022.
The best known of the street agents is isotonitazene (street names “Iso” and “Tony”), a 5-nitro-2-benzyl‐benzimidazole opioid that was identified among street drugs in Europe, with metonitazene emerging in the US recreational drug market in the first half of 2020.
“However, its presence likely is under-detected because many testing facilities are not set up to test for isotonitazene, or any other nitazenes,” Professor Varrassi said.
“Nitazenes were specifically developed to be cheap, easy to manufacture, and highly intoxicating. Even if street drug buyers understand they are buying heroin mixed with nitazenes, the quality and quantity of the nitazene would likely not be disclosed. The purveyors of these illicit street drugs may themselves be unaware of nitazene content in their products.”
Professor Vaarrassi said that the potential challenges to clinical care were enormous.
“Patients in overdose-induced respiratory distress are often unresponsive and thus can provide no information to those treating them. Even if responsive or accompanied by other people, these overdose victims may not know what they have taken,” he said.
“Current drug testing equipment for nitazenes is often not available and conventional fentanyl test strips cannot detect their presence, and as such, most clinicians treating people with drug-induced respiratory depression may not even consider the presence of nitazenes.”