Fentanyl misuse

Are carfentanil and acrylfentanyl naloxone resistant?

The rapid rise in deaths since 2012 due to opioid poisoning is correlated with the proliferation of potent synthetic opioid agonists such as fentanyl, acrylfentanyl, and carfentanil. The efficacy of frontline antidotes such as naloxone in reversing such poisoning events has been questioned, and the possibility of naloxone-resistant synthetic opioids has been raised. In this manuscript, we applied in vitro techniques to establish the median effective inhibitory concentrations for fentanyl, acrylfentanyl, and carfentanil and subsequently evaluate naloxone's ability to reverse agonist-receptor interactions.

Recent changes in trends of opioid overdose deaths in North America

Background

As several regulatory and environmental changes have occurred in North America, trends in overdose deaths were examined in the United States (US), Ontario and British Columbia (BC), including changes in consumption levels of prescription opioids (PO) and overdose deaths, changes in correlations between consumption levels of PO and overdose deaths and modeled differences between observed and predicted overdose deaths if no changes had occurred.

Methods

Consumption levels of PO included defined daily doses for statistical purposes per million inhabitants per day for the US and Canada (2001–2015). Overdose deaths included opioid overdose deaths for the US (2001–2017) and Ontario (2003–2017) and illicit drug overdose deaths for BC (2001–2017). The analytic techniques included structural break point analyses, Pearson product-moment correlations and multivariate Gaussian state space modeling.

Results

Consumption levels of PO changed in the US in 2010 and in Canada in 2012. Overdose deaths changed in the US in 2014 and in Ontario and BC in 2015. Prior to the observed changes in consumption levels of PO, there were positive correlations between consumption levels of PO and overdose deaths in the US (r = 0.99, p < 0.001) and Ontario (r = 0.92, p = 0.003). After the observed changes in consumption levels of PO, there was a negative correlation between consumption levels of PO and overdose deaths in the US (r = − 0.99, p = 0.002). Observed overdose deaths exceeded predicted overdose deaths by 5.7 (95% Confidence Interval [CI]: 4.8–6.6), 3.5 (95% CI: 3.2–3.8) and 21.8 (95% CI: 18.6–24.9) deaths per 100,000 people in the US, Ontario and BC, respectively in 2017. These excess deaths corresponded to 37.7% (95% CI: 31.9–43.6), 39.2% (95% CI: 36.3–42.1) and 72.2% (95% CI: 61.8–82.6) of observed overdose deaths in the US, Ontario and BC, respectively in 2017.

Conclusions

The opioid crisis has evolved in North America, as a sizeable proportion of overdose deaths are now attributable to the several regulatory and environmental changes. These findings necessitate substance use policies to be conceptualized more broadly as well as the continued expansion of harm reduction services and types of pharmacotherapy interventions.