On 9 November 2023, Ireland’s Health Service Executive (HSE) was made aware of an overdose cluster in Dublin, with 24 cases notified throughout the day and another 10 cases the following morning. This triggered an urgent review across a number of information sources to identify possible signals of change on the Dublin drug market.1 Data were monitored by the HSE on 9–12 November, and a total of 57 non-fatal overdoses were recorded during this period. Analysis by Forensic Science Ireland of a sample obtained by An Garda Síochána on the evening of 10 November confirmed the emergence of nitazenes in a light brown/sandy-coloured powder on the Dublin heroin market, which resulted in the HSE issuing a Red Alert for the city. The nitazene was later confirmed as N-pyrrolidino protonitazene (protonitazepyne), which was a first identification for Ireland and a substance under intensive monitoring by the European Union Drugs Agency (EUDA). Samples were also found to contain caffeine, paracetamol, benzoic acid, and mannitol.2

Nitazenes are strong synthetic opioids developed in the 1950s as opioid analgesics, but due to their high potential for overdose were never approved to market. Nitazenes have been connected to a number of overdose deaths worldwide and have also been found in tablets (fake oxycodone), heroin, ketamine, and synthetic cannabinoids.3

In addition to the initial Dublin outbreak, nitazenes have since been detected on the Cork market following a steady increase of overdoses in the city; on 12 December 2023, there were 13 non-fatal overdoses reported to the HSE over a 6-day period. This outbreak was attributed to the same nitazene identified in Dublin. On 15 March 2024, the HSE extended a Red Alert to Irish prison settings following a number of overdoses (<5).

On Thursday, 18 July 2024, the Irish Prison Service issued an urgent drug alert to all prisons following analyses conducted by the HSE which confirmed the presence of a nitazene-type substance associated with a number of overdoses in Irish prisons, one of which was fatal. The HSE has convened a National Red Alert Group consisting of key stakeholders to monitor and respond to synthetic opioids. Frontline services nationally have been advised to convene and begin developing strategies for managing outbreaks. This includes establishing coordination groups and formal reporting of drug market changes or overdose clusters to the HSE.

In a letter to the editor of the journal Addiction,4 Killeen et al. note that the Irish nitazene outbreaks are examples of how substances can emerge without warning and sporadically on the illicit drug market. Outbreaks require urgent responses and, in the Irish case, current structures were adapted without unwieldy policy amendments. They suggest that this approach will not be sustainable on a long-term basis and that increased budget allocation should be provided to improve early warning mechanisms, to expand harm reduction and treatment responses, and to enhance drug checking through a dedicated drug-monitoring laboratory in Ireland.

1    Drugs.ie (2023) Synthetic opioid preparation: HSE update on the emergence of synthetic opioids on the Irish market. Available from: https://www.drugs.ie/synthetic_opioid_preparation/

2    Killoran S, McNamara S, Kavanagh P, O’Brien J and Lakes R (2024) Identification of N-pyrrolidino protonitazene in powders sold as heroin and associated with overdose clusters in Dublin and Cork, Ireland. Drug Test Anal. Early online. Available from: https://www.drugsandalcohol.ie/41058/

3    Pergolizzi J, Raffa R, LeQuang JAK, Breve F and Varrassi G (2023) Old drugs and new challenges: a narrative review of nitazenes. Cureus, 15(6): e40736.

4    Killeen N, Lakes R, Webster M, Killoran S, McNamara S, Kavanagh P, et al. (2024) The emergence of nitazenes on the Irish heroin market and national preparation for possible future outbreaks. Addiction, 119(9): 1657–1658. Available from: https://www.drugsandalcohol.ie/40996/