Warning: This article contains descriptions of drugs use
Deadly new drugs found in fake medicines in the UK
A government spokesperson said it was “securing our borders from the threat” through “world-leading intelligence, dedicated cross-government taskforce and extensive international networks”.
The contaminated substances were identified in anonymous samples submitted to WEDINOS, the only national drug-checking service in the UK.
It said the fake medicines looked like "the same kind of packet you might get from your chemist on the high street" but were "most likely purchased from illicit online pharmacies".
Anne Jacques had never heard of nitazenes when a police officer knocked at her door in the early hours of 17 July 2023 and said her son had been found dead at his student flat.
Alex Harpum, 23, had been preparing for a career as an opera singer and had been accepted for a two-year masters course.
“Watching him sing was one of the biggest joys in my life ever,” Ms Jacques said.

It was initially suspected the cause of his death was sudden adult death syndrome, but eight months later Alex's family learned he had taken a substance contaminated with a nitazene.
Phone records suggested he had tried to buy tablets usually sold as Xanax, which are only available with a private prescription in the UK.
Ms Jacques, who lives in north Wales, believes Alex was doing so because he often struggled with sleeping while taking medication for his attention deficit hyperactivity disorder.
The traces of nitazenes were only detected after she queried with police why earlier tests had not looked for them.
Ms Jacques said she remained in “disbelief" at the lack of testing, adding: “If I hadn’t pushed for better answers in the middle of massive grief, then to this day I would have no idea how he actually died.
"Unless we’re testing for them, how is anyone going to be aware and informed [of the dangers]?"
A Scotland Yard spokesperson said there had been “delays beyond the control of the Met” relating to the need for, and timing of, specialist testing in this case.
The North London Coroner Service said it remained in contact with the family regarding their concerns.

Mr Raithelhuber said there was a "lesson to learn... from North America", where people became addicted to prescription painkillers before the use of fake medicines containing fentanyl became widespread.
“So here in Europe, we are not yet in that situation, but this could be the early signs of traffickers trying to expand," he said.
“I think it's a warning call, maybe for all other countries in Europe… that nitazenes are probably here to stay for the time being, and that their potential negative impact on the health of users is huge.”
He said because both benzodiazepines and nitazenes were depressants, “their combined effect increases the risk of overdose significantly”.
Synthetic opioid effects
Signs that someone may have taken one of these drugs:
Anyone who has consumed synthetic opioids and experiences the symptoms described should seek urgent medical treatment.
Source: Metropolitan Police
The groups of people most at risk were “those who have always been at the highest risk of all drug-related harm,” said Harry Sumnall, a professor in substance use at Liverpool John Moores University.
He said this included people with drug use problems and those “using drugs to help manage their life circumstances”.