Ontario Drug Policy Research Network

Part of the June 2026 issue supplement, to be published in its entirety on May 12, 2026.

Part of the June 2026 issue supplement, to be published in its entirety on May 12, 2026.

Early in the SARS-Cov-2 pandemic, modified clinical guidance recommended the provision of take-home methadone doses for those previously ineligible to facilitate social distancing. Following this change, studies reported improved treatment retention among patients granted expanded access to take-home doses. However, most patients resumed daily dispensed methadone within six months. Factors associated with the return to daily dispensed methadone remain unknown. Therefore, we conducted a population-based cohort study to identify patient and prescriber-related characteristics associated with return to daily dispensed methadone. Our study included all residents of Ontario, Canada who received daily dispensed methadone on March 21, 2020, and were then provided at least one take-home dose between March 22, 2020, and April 21, 2020. Follow-up time was divided into 14-day discrete time intervals. The primary outcome was return to daily dispensed methadone, defined as the first interval where a take-home dose was not dispensed. A multilevel discrete time survival model with a complementary log-log link function and random intercepts across prescribers to account for patient clustering by prescriber was used to approximate cause-specific hazard ratios. Within 26 weeks, 1,675 (58.5%) individuals were reverted to daily dispensed methadone. Person-level variables significantly associated with our primary outcome included occurrence of an emergency department visit during or before the interval of interest (HR = 1.27; 95% CI = 1.05, 1.55) and missed methadone dose(s) in the interval prior (HR = 1.59; 95% CI = 1.44, 1.76). Lastly, patients prescribed methadone by a high-volume (top 20th percentile) opioid agonist treatment prescriber had an increased hazard of return to daily dispensed methadone compared to those prescribed methadone by a low-volume (50th percentile) prescriber (HR = 1.44; 95% CI = 1.14, 1.83). While patient characteristics that may indicate clinical instability, such as recent history of missed methadone dose(s) were associated with return to daily dispensed methadone, prescriber OAT client volume was also be associated this outcome.

IntroductionThe period following hospital discharge for opioid toxicity presents an increased risk for repeat events. While opioid agonist treatment (OAT) can reduce this risk, in-hospital initiation rates remain low, and the impact of early initiation on subsequent repeat toxicities is not well understood.MethodsWe conducted a population-based cohort study of Ontario residents discharged following a hospital-treated opioid toxicity between 1 January 2014 and 31 December 2021, followed to 31 July 2022. The exposure was OAT initiation within 30 days of discharge, with a subgroup analysis of OAT initiation within 1 day. The primary outcome was repeat opioid toxicity within 6 months. Stabilised inverse probability treatment weighting (sIPTW) was used to balance baseline covariates, and Cox proportional hazards models to assess the association between OAT initiation and hazard of repeat events.ResultsOur cohort included 20 523 opioid toxicities of which 68.5% were male, with a mean age of 36.5 years. Before sIPTW, important differences were observed, including more prior year opioid toxicities (mean 1.35 vs 1.05; standardised difference (Std Diff)= 0.18) and greater public drug benefit eligibility (70.1% vs 58.1%; Std Diff=0.25) among the exposed. Overall, 2544 people (12.4%) initiated OAT within 30 days of hospital discharge. In weighted models, people who initiated OAT in the month following discharge had a lower hazard of repeat toxicity (1.62 per 1000 person-days) compared with those who did not (2.04 per 1000 person-days; weighted HR=0.57; 95% CI 0.47 to 0.69). Findings were consistent in our subgroup analysis (weighted HR=0.44; 95% CI 0.57 to 0.91).ConclusionsAmong the small proportion who initiated OAT after a hospital-treated opioid toxicity, there was a significant reduction in repeat toxicities, emphasising the importance of early OAT initiation. To facilitate this, care pathways between hospital and community must be strengthened through enhanced investments in addiction medicine training, hospital resources and reducing stigma in hospitals.

Alpha-2 agonists have been used as anesthetic adjuncts for a very long time. Initially, drugs such as xylazine and detomidine were almost solely used for veterinary practice. Subsequent studies demonstrated the effectiveness of deep anesthesia in animals employing the newer, more potent, and selective alpha-2-agonists, such as the stereoisomer of medetomidine, dexmedetomidine (D-isomer). In the […]

ABSTRACT Objective: The aim of this study was to compare time on treatment among individuals initiating buprenorphine/naloxone and methadone and understand how retention varies according to age, sex, and urban/rural residence. Methods: We conducted a population-based retrospective cohort study among individuals aged 18 years and older, residing in Southern Ontario, Canada, who initiated buprenorphine/naloxone or methadone between October 2016 and December 2018 (N=15,724). We compared time on treatment across demographic and geographic subgroups. Our primary outcome was time to treatment discontinuation, defined as missing at least 14 consecutive days of opioid agonist therapy (OAT). Results: We identified 15,724 eligible individuals, among whom 7209 (45.8%) initiated buprenorphine/naloxone and 8515 (54.2%) initiated methadone. The median time to treatment discontinuation was significantly shorter among those initiating buprenorphine/naloxone rather than methadone (114 d, interquartile range:15–665 d vs. 263 d interquartile range: 32–1015 d, respectively, P<0.0001). Time on treatment increased with age in both OAT groups, with the exception of those aged 65 and older, where retention declined. Among methadone recipients, time on treatment was longer among rural relative to urban residents (372 vs. 255 d; P=0.0073), with no variation by sex. Conversely, females treated with buprenorphine/naloxone had significantly longer treatment retention than men (125 vs. 108 d; P=0.0372), with no variation by urban or rural residence. Conclusions: Treatment retention is lower among individuals treated with buprenorphine/naloxone relative to methadone. Moreover, retention varies between and within OAT groups by demographic variables and place of residence. Further research which aims to explain these differences is needed to optimize OAT treatment. Objectifs de l'étude: Comparer la durée du traitement chez les personnes qui commencent à prendre de la buprénorphine/naloxone et de la méthadone et comprendre comment la rétention varie en fonction de l'âge, du sexe et du lieu de résidence (urbain ou rural). Méthodes: Nous avons mené une étude de cohorte rétrospective basée sur la population parmi les personnes âgées de 18 ans et plus, résidant dans le sud de l’Ontario, au Canada, qui ont commencé à prendre de la buprénorphine/naloxone ou de la méthadone entre octobre 2016 et décembre 2018 (N=15 724). Nous avons comparé la durée du traitement entre les sous-groupes démographiques et géographiques. Notre résultat principal était le temps écoulé jusqu'à l’arrêt du traitement, défini comme l’absence d’au moins 14 jours consécutifs de traitement par agoniste opioïde (TAO). Résultats: Nous avons identifié 15 724 personnes éligibles, parmi lesquelles 7 209 (45,8%) ont commencé à prendre de la buprénorphine/naloxone et 8 515 (54,2%) de la méthadone. Le temps médian avant l’arrêt du traitement était significativement plus court chez les personnes ayant commencé la buprénorphine/naloxone plutôt que la méthadone (114 jours, intervalle interquartile [IQR] 15-665 jours contre 263 jours IQR 32-1 015 jours, respectivement, P<0.0001). La durée du traitement a augmenté avec l'âge dans les deux groupes de TAO, à l’exception des personnes âgées de 65 ans et plus, chez qui la rétention a diminué. Parmi les patients traités à la méthadone, la durée du traitement était plus longue dans les zones rurales que dans les zones urbaines (372 jours contre 255 jours; P=0.0073), sans variation selon le sexe. Inversement, les femmes traitées à la buprénorphine/naloxone avaient une durée de traitement significativement plus longue que les hommes (125 jours contre 108 jours ; P=0.0372), sans variation selon le lieu de résidence (urbain ou rural). Conclusion: La rétention du traitement est plus faible chez les personnes traitées à la buprénorphine/naloxone qu’avec la méthadone. De plus, la rétention varie entre et au sein des groupes TAO en fonction des variables démographiques et du lieu de résidence. Des recherches supplémentaires visant à expliquer ces différences sont nécessaires pour optimiser le traitement par TAO.

Pathological aggregation and propagation of the protein alpha-synuclein (α-syn) in a prion-like fashion underlie the progression of Parkinson’s disease (PD). Understanding how these aggregates propagate from cell to cell thus holds great therapeutic promises. Despite years of efforts, the process of α-syn aggregate uptake, including in dopaminergic neurons that are the primary cell type lost in PD, remains unclear and debated. With this objective in mind, a FACS-based, unbiased genome-wide CRISPR/Cas9 screening was conducted in human retina-pigmented epithelial cells (RPE-1) to identify genes, the invalidation of which modulates the extent of fluorescent α-syn preformed fibrils (PFFs) uptake.

The COVID-19 pandemic has exacerbated the overdose crisis in Canada. Using data from ICES and the Office of the Chief Coroner of Ontario, the authors characterized changing patterns of medication use and health services utilization during the pandemic. This analysis suggests that responses to the overdose crisis must confront the rapidly changing unregulated drug supply with a tailored response that addresses varied population needs, expands accessible treatment and harm reduction services and responds to the missed opportunities for engagement and support within various healthcare settings.