Research and analysis

Government response to the ACMD's sixth addendum advice on nitazenes (accessible)

Updated 10 December 2025

Professor Owen Bowden-Jones
Chair, Advisory Council on the Misuse of Drugs (ACMD)
Professor Simon Thomas
Chair, ACMD New Psychoactive Substances Committee
C/o ACMD Secretariat
1st Floor, Peel Building
2 Marsham Street
London, SW1P 4DF

By e-mail only: ACMD@homeoffice.gov.uk

9 December 2025

Dear Owen and Simon,

Sixth addendum to Advisory Council on the Misuse of Drugs (ACMD) report on the use and harms of 2-benzyl-benzimidazole (‘nitazene’) and piperidine benzimidazolone (‘brorphine-like’) opioids

I would like to thank the ACMD for the recent advice dated 21 October 2025 on the sixth addendum to the generic definition of 2-benzyl benzimidazole opioids (nitazenes).

As you are aware, following the advice from the ACMD published on 5 April 2024, we have introduced a generic definition of nitazenes as Class A drugs under the Misuse of Drugs Act 1971 (‘MDA 1971’).  We have also added this generic definition of nitazenes to Schedule 1 to the Misuse of Drugs Regulations 2001 (‘MDR 2001’) and designated it under the Misuse of Drugs (Designation) (England, Wales and Scotland) Order 2015 (‘2015 Order’).  These changes came into force on 15 January 2025 and followed the other 14 named nitazene controls which were introduced on 20 March 2024.  On 8 November 2024 the ACMD published a fifth addendum to its original report on nitazenes, which highlighted that carbamoyl derivatives and aminoisotonitazene had been identified in the UK, and recommended that a consultation be undertaken with stakeholders on amendments to the generic definition of nitazenes which would capture those substances.  On 29 January 2025 my predecessor accepted that recommendation.

I would like to thank the ACMD, especially the Novel Psychoactive Substances Committee, for its vigilance in identifying new nitazenes.  Nitazenes are some of the most lethal drugs and do significant harm to individuals and communities.  Identifying and controlling new nitazenes strengthens the tools available to law enforcement and the criminal justice system for tackling these deeply harmful substances. 

I note that you have identified two new nitazenes – ethylene etonitazene and ethylene isotonitazepyne (N-pyrrolidino ethylene isotonitazene) – which are not captured in the current generic definition, and your advice that that definition be updated to capture those substances and associated phenethyl variants which may appear in the future.

I formally accept the ACMD sixth addendum recommendation and will consult stakeholders, including academia and the chemical and pharmaceutical industries, on the amendments set out in bold text below:

“Any compound (not being a compound for the time being specified in sub- paragraph (a) above), with a maximum molecular mass of 500 atomic mass units, structurally derived from 2-(2-benzyl-benzimidazol-1-yl)ethanamine by modification in any of the following ways, that is to say:

i) By substitution at the nitrogen of the ethanamine to any extent by alkyl substituents containing up to three carbon atoms or alkenyl substituents containing up to three carbon atoms or by inclusion of the nitrogen atom (and no other atoms of the side chain) in a cyclic structure.

ii) By substitution in the phenyl ring of the benzyl system to any extent by alkyl or haloalkyl containing up to six carbon atoms, alkoxy or haloalkoxy containing up to five carbon atoms, acetyloxy, hydroxy, cyano, halogen, thioalkyl containing up to five carbon atoms or alkylsulphonyl containing up to five carbon atoms.

iii) By substitution at the 5- or 6- positions of the benzimidazole system by nitro, acetyl, amino, cyano, methoxy, trifluoromethyl, trifluoromethoxy or halogen substituents.

iv) By substitution at the benzylic carbon by a methyl group or by a carbamoyl group.

v) By replacement of the benzylic carbon or of a carbon atom of an ethyl link between the benzimidazole system and the phenyl ring by a nitrogen, oxygen or sulphur atom

vi) By substitution in the phenyl ring of the benzyl system by an ethoxy group linked back to the phenyl ring to form a dihydrobenzofuran structure.

vii) By replacement of the phenyl ring of the benzyl system by methylenedioxyphenyl.

viii) By replacement of the methyl group of the benzyl system by an ethyl group to form a phenethyl system”

The consultation will also cover the amendments from the ACMD’s fifth addendum to its report on nitazenes (shown in paragraph (iii) and (iv), above), and some other proposed amendments to Schedule 2 to the MDA 1971 to control new drugs and amend those already controlled.

Following this consultation, we will introduce legislation to include this amended generic definition of nitazenes as a Class A drug under the MDA 1971, as well as placing it in Schedule 1 to the MDR 2001 and designating it under the 2015 Order.

Very best wishes,

Sarah Jones MP

Minister of State for Policing and Crime