Drugs A-Z

Scientific Names: 2-Benzyl benzimidazole opioids

Generic Names: Enwau Generig: A group of drugs commonly known as ‘Nitazenes’

An example of what Nitazenes looks like
‘Nitazenes’ is the common name for a group of extremely potent synthetic opioids. ‘Nitazenes’ can appear be in the form of an off white to light brown powder, although at present they are very rarely seen as street drugs but have been detected as adulterants in street heroin and a range of other drugs. These include oxycodone tablets, alprazolam (Xanax) powder, 10mg fake diazepam tablets, zopiclone and promethazine, ‘Spice’ (synthetic cannabinoids) and even powdered cocaine.

Nitazenes vary in potency from Butonitazene which is estimated to be twice the potency of heroin, up to N-pyrrolidino protonitazene which is estimated to be over 1,000 times the potency of heroin.

There were at least 27 deaths known to involve ‘nitazenes’ during 2021, mainly thought to involve an adulterated batch of heroin in the South of England. Between June 2023 and January 2024, they have been at least 65 confirmed ‘nitazene’ deaths in England and Scotland and at least that number again where the outcome of tests is yet to be confirmed.

There is a national concern that because of a crack down on opium production by the Taliban in Afghanistan, where the vast majority of UK street heroin originates, there will be a UK heroin shortage. This could lead to more adulteration of street heroin with ‘nitazenes’ or other potent synthetic opioids.

Desired Effects:

At present, ‘nitazenes’ are almost exclusively found as unwanted adulterants or mis-sold as other street drugs, so the effects are not desired. The actual effects are like other potent synthetic opioids such as fentanyl, however ‘nitazenes’ have been reported as leading directly to overdose and unconsciousness without any sort of desirable high first.

Side Effects:

  • Nausea and vomiting
  • Drowsiness
  • Decreased heartrate.
  • Shallow breathing
  • Very high risk of overdose
  • Nitazenes are far more likely to lead to overdose than street heroin, so it is even more important you do what you can to reduce risks.

    • Although some people have said that ‘nitazene’ powder mis-sold as heroin will look different to street heroin when cooked, these reports vary and are inconsistent. If poor quality heroin has been adulterated with tiny amounts of ‘nitazenes’ it is unlikely to look noticeably different.
    • There is no way of telling by looking at them if other street drugs in tablet or powdered form contain ‘nitazenes’.
    • There have been some test strips recently developed to detect ‘nitazenes’, but at present these are not widely available, and it is unknown how accurate they are or which of the ‘nitazenes’ they are able to detect.
    • It is even more important now to start a new batch/bag of heroin with a small test dose rather than using the whole lot in one go.
    • Smoking heroin is safer than injecting and is far less likely to lead to overdose and far less likely to lead to blood borne viruses like Hepatitis B & C and HIV.
    • If you have had a break from using opioids, your tolerance will be significantly lowered, and you are at a greater risk of overdose.
    • Avoid using alone as there is nobody around to help if you overdose. If you use with someone else take it in turns to use.
    • Always carry naloxone. Naloxone temporary reverses the effects of a ‘nitazene’ overdose. However, more doses of naloxone may be needed than with a heroin overdose, so be sure to get enough naloxone from your drug service.
    • If someone has overdosed from an opioid, put them in the recovery position and call for emergency help immediately. Use naloxone if you have it.
    • People taken to hospital after a ‘nitazene’ overdose, may have to stay in longer. This is because naloxone only works temporarily and as ‘nitazenes’ are far more potent than heroin, you are more likely to overdose again after the naloxone has worn off.
    • Using ‘nitazenes’ (knowingly or unknowingly) with other drugs can increase the risk of overdose, especially drugs like alcohol, benzo's, pregabalin and gabapentin and methadone.
    • As with injecting any drug - Never share your needles or works with anyone else, no matter how well you know them.

    Long term risks:

    Like other potent synthetic opioids, ‘nitazenes’ are highly likely to produce dependence. If ‘nitazene’ adulteration of street drugs becomes common and/or if an illicit market for ‘nitazenes’ develops, it is likely there will be a significant rise in drug related deaths.

    Short term risks:

    Heroin and other opioids already make up the largest proportion of drug-related deaths which have more than doubled in England and Wales since 2012. As ‘nitazenes’ are far more potent, mis-sold, or adulterated street heroin containing ‘nitazenes’ are far more likely to lead to a fatal overdose. There is limited information known about the human use of ‘nitazenes’. Quite apart from big differences in potency, one recent study from a US hospital indicated that as well as the respiratory depression (slow shallow breathing) associated with opioid overdose, Metonitazene was associated with cardiac arrest (heart attack). As with deaths involving heroin, many of the ‘nitazene’ deaths have also involved the use of other drugs like diazepam and pregabalin taken at the same time.
    Like other opioids, ‘nitazenes’ are central nervous system depressant, analgesic.
    Nitazenes can be taken orally; snorted, taken sublingually via a spray, vaped, smoked (if in a ‘free base’ form), and injected.
    ‘Nitazenes’ were developed as pain killing medication in the 1950s but were found to be too risky to be developed further by the pharmaceutical industry, so have never been used as medicines.
    It is thought they are mainly produced in China. As a result of legislation introduced by the Chinese government to crack down on the production of various fentanyl like synthetic opioids, Chinese producers are thought to have switched to making ‘nitazenes’.
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