An alert has been issued in the UK due to the presence of isotonitazepyne in tablets sold as oxycodone (oxy).
https://x.com/WeAreTheLoopUK/status/1928460931123630102

Nitazenes have similar effects to oxycodone or heroin, but the amount of drug required is much lower. Black market tablets can easily contain many times the “equivalent dose” of the substances normally in prescribed tablets, making it easy to take too much and overdose.
If you or a friend feel drowsy and notice symptoms like shallow breathing, loss of consciousness, blue or grey lips, or obstructed breathing, call 999.
Isotonitazepyne (aka N-pyrollidino isotonitazene) is a novel member of the nitazene family, produced with a small modification compared to isotonitazene. It is similarly dangerous to the other nitazenes and carries a high risk of fatal overdose.
Isotonitazepyne is illegal in the UK and falls into Class A under the generic definition of 2-benzyl benzimidazole derived opioids because it contains the backbone with only the following modifications:
- The 5- position of the benzimidazole system is substituted by a nitro group.
- The nitrogen of the ethanamine (and no other atoms of the side chain) is included in a cyclic structure.
- The phenyl ring of the benzyl system is substituted by an alkoxy group containing three carbon atoms.