Introduction
Opioid-related morbidity and mortality continue to represent a major public health burden globally and in Ireland. Opioid agonist treatment (OAT) is associated with substantial reductions in all-cause mortality, reduced overdose risk, reduced criminality, and improved psychosocial outcomes (Kabra et al. Reference Kabra, Srivastava, Gautam, Singh, Oksanen, MacDonald, Lee, Boyett, Santoro, Gupta, Jong-Laird and Ren2026; Santo et al. Reference Santo, Clark, Hickman, Grebely, Campbell, Sordo, Chen, Tran, Bharat, Padmanathan, Cousins, Dupouy, Kelty, Muga, Nosyk, Min, Pavarin, Farrell and Degenhardt2021). Methadone has traditionally been the dominant treatment modality globally, with maintenance treatment requiring supervised dosing (from daily to weekly) under Irish OAT guidelines (Health Service Executive 2016). Access to oral buprenorphine treatment (sublingual tablet) was progressed in 2017 on foot of the Misuse of Drugs Regulations 2017 (Irish Statute Book 2017), allowing for the use of buprenorphine containing products as part of OAT. The therapeutic landscape has further evolved with the introduction of prolonged-release, weekly and monthly, injectable formulations of buprenorphine, sold in Ireland as Buvidal® (Haight et al. Reference Haight, Learned, Laffont, Fudala, Zhao, Garofalo, Greenwald, Nadipelli, Ling and Heidbreder2019; Lofwall et al. Reference Lofwall, Walsh, Nunes, Bailey, Sigmon, Kampman, Frost, Tiberg, Linden, Sheldon, Oosman, Peterson, Chen and Kim2018).
Recent budgetary developments within Ireland have increased funding for buprenorphine, including long-acting formulations, within publicly funded addiction services (Department of Health 2025). This policy shift represents an important opportunity to optimise OAT delivery and broaden treatment choice.
Rationale for prolonged-release buprenorphine
Pharmacological and safety considerations
Buprenorphine is a partial µ-opioid receptor agonist with high receptor affinity and a ceiling effect on respiratory depression, contributing to a favourable safety profile (Haight et al. Reference Haight, Learned, Laffont, Fudala, Zhao, Garofalo, Greenwald, Nadipelli, Ling and Heidbreder2019; Maremmani et al. Reference Maremmani, Dematteis, Gorzelanczyk, Mugelli, Walcher and Torrens2023). Compared with methadone, it is associated with lower overdose risk, reduced QTc prolongation, fewer drug–drug interactions, and improved safety in polypharmacy populations (Kabra et al. Reference Kabra, Srivastava, Gautam, Singh, Oksanen, MacDonald, Lee, Boyett, Santoro, Gupta, Jong-Laird and Ren2026; Santo et al. Reference Santo, Clark, Hickman, Grebely, Campbell, Sordo, Chen, Tran, Bharat, Padmanathan, Cousins, Dupouy, Kelty, Muga, Nosyk, Min, Pavarin, Farrell and Degenhardt2021). Depot formulations provide weekly or monthly subcutaneous administration, potentially eliminating the need for regular supervised consumption requirements.
Adherence and retention
Retention remains a key predictor of mortality outcomes in opioid use disorder (OUD). Prolonged-release buprenorphine (PRB) improves adherence by ensuring continuous medication delivery between injections, reducing missed doses, diversion and chaotic use (Haight et al. Reference Haight, Learned, Laffont, Fudala, Zhao, Garofalo, Greenwald, Nadipelli, Ling and Heidbreder2019; Hard and DeSilva Reference Hard and DeSilva2023; Ling et al. Reference Ling, Shoptaw and Goodman-Meza2019), with retention outcomes approaching those of methadone in appropriately supported programmes (Ivasiy et al. Reference Ivasiy, Madden, Johnson, Machavariani, Ahmad, Oliveros, Tan, Kil and Altice2025; Lee et al. Reference Lee, Malone, McDonald, Cheng, Vasudevan, Tofighi, Garment, Porter, Goldfeld, Matteo, Mangat, Katyal, Giftos and MacDonald2021).
Evidence from recent literature (2021–2026)
Recent studies demonstrate that PRB is associated with improved quality of life, including participating in employment and education, reduced illicit opioid use, and high patient satisfaction (Heil et al. Reference Heil, Salzman, Hunter, Baston, Milburn, Schmidt, Haroz and Ganetsky2024; McNicholas et al. Reference McNicholas, Scully and Keenan2023; Yarborough et al. Reference Yarborough, Stumbo, Janoff, Keast, Leo and Leitz2024). Comparative analyses suggest that PRB demonstrates promising retention outcomes, greater perceived autonomy, and reduced treatment-related stigma (Johnson et al. Reference Johnson, Monwell and Capusan2024). Evaluations conducted during and following the COVID-19 pandemic suggest that PRB reduced the need for frequent clinic attendance while supporting continuity of care (Heil et al. Reference Heil, Salzman, Hunter, Baston, Milburn, Schmidt, Haroz and Ganetsky2024; Ling et al. Reference Ling, Shoptaw and Goodman-Meza2019). Observational studies have demonstrated reductions in emergency healthcare utilisation (Yarborough et al. Reference Yarborough, Stumbo, Janoff, Keast, Leo and Leitz2024).
In keeping with evolving international practice, the Maudsley Prescribing Guidelines in Psychiatry note that PRB is licensed in the United Kingdom, and Australia saw prescribing increased from approximately 4% in 2019 to nearly 50% in 2022 (Taylor et al. Reference Taylor, Barnes and Young2025). Long-acting injectable buprenorphine also forms part of the 10-year drug strategy in England (Taylor et al. Reference Taylor, Barnes and Young2025), reflecting growing international confidence in this treatment modality and providing a strong policy rationale for Ireland to continue expanding access.
Real-world outcomes from the Irish National Drug Treatment Centre Buvidal Pilot (2020–2024)
A Quality Improvement Project at the HSE National Drug Treatment Centre (NDTC) provides important Irish real-world experience with PRB. The pilot phase operated between December 2020 and May 2024 and was subsequently incorporated into routine clinical care. Across both pilot and subsequent routine service delivery, 161 patients commenced Buvidal between December 2020 and March 2026, with 78 remaining in active treatment at the time of reporting.
Clinical feedback has been consistent with benefits reported in the literature, with many patients reporting subjective improvements in treatment experience and day-to-day functioning within three months. Discontinuation occurred due to detoxification completion, adverse effects or patient preference for alternative treatments, reflecting the importance of flexible, patient-centred care pathways.
Service-level implications
The expansion of PRB may offer several service-level and patient-centred benefits, including reduced treatment-related stigma associated with daily pharmacy attendance, a lower risk of diversion, greater autonomy, and flexibility in treatment engagement, improved accessibility for individuals experiencing homelessness or criminal justice involvement, and enhanced workforce efficiency through reduced dispensing requirements (Haight et al. Reference Haight, Learned, Laffont, Fudala, Zhao, Garofalo, Greenwald, Nadipelli, Ling and Heidbreder2019; Johnson et al. Reference Johnson, Monwell and Capusan2024; Maremmani et al. Reference Maremmani, Dematteis, Gorzelanczyk, Mugelli, Walcher and Torrens2023). Given the changing drug landscape across Europe highlighted in the European Drug Report 2026 (European Union Drugs Agency 2026), this could free up trained Addiction service staff to work with people presenting with problems associated with non-opioid drugs.
Addressing implementation challenges
The initial acquisition cost of PRB may be higher than daily sublingual formulations or methadone, but emerging evidence suggests that these costs may be partially offset by reductions in healthcare utilisation and service delivery burden (Jackson et al. Reference Jackson, Mandell, Johnson, Chatterjee and Vanness2015). Observational data indicate reductions in acute healthcare utilisation, including emergency department presentations, following initiation of PRB (Yarborough et al. Reference Yarborough, Stumbo, Janoff, Keast, Leo and Leitz2024). Depot formulations reduce opportunities for medication diversion which may indirectly reduce broader system costs (Haight et al. Reference Haight, Learned, Laffont, Fudala, Zhao, Garofalo, Greenwald, Nadipelli, Ling and Heidbreder2019; Maremmani et al. Reference Maremmani, Dematteis, Gorzelanczyk, Mugelli, Walcher and Torrens2023). Overall, PRB may achieve cost neutrality or generate savings through reduced healthcare utilisation and improved service efficiency.
A strategic opportunity for Irish services
The 2026 HSE funding allocation (Department of Health 2025) provides an opportunity to expand access to PRB, modernise addiction services, and reduce financial barriers.
Ethical and clinical considerations
OUD is a chronic relapsing condition requiring long-term management (Kabra et al. Reference Kabra, Srivastava, Gautam, Singh, Oksanen, MacDonald, Lee, Boyett, Santoro, Gupta, Jong-Laird and Ren2026; Santo et al. Reference Santo, Clark, Hickman, Grebely, Campbell, Sordo, Chen, Tran, Bharat, Padmanathan, Cousins, Dupouy, Kelty, Muga, Nosyk, Min, Pavarin, Farrell and Degenhardt2021). Depot buprenorphine is associated with increased autonomy and reduced treatment burden, supports harm reduction through improved adherence and reduced illicit opioid use, and aligns with recovery-oriented models of care (Johnson et al. Reference Johnson, Monwell and Capusan2024; Kabra et al. Reference Kabra, Srivastava, Gautam, Singh, Oksanen, MacDonald, Lee, Boyett, Santoro, Gupta, Jong-Laird and Ren2026; Neale et al. Reference Neale, Tompkins and Strang2019). Clinicians should seek to ensure that evidence-based, patient-centred treatment options are available and discussed with eligible patients.
Conclusion
The available evidence, evolving international practice and recent HSE investment support PRB as an increasingly important component of OAT in Ireland, and continued expansion alongside ongoing outcome evaluation may help optimise care for people living with OUD.
Acknowledgements
The authors acknowledge the contribution of clinical teams involved in the delivery of opioid agonist treatment services in Ireland.
Funding statement
No specific funding was received for this work.
Competing interests
The authors declare no conflicts of interest.
Ethical standards
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committee on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.
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