Background
Escalation of pharmaceutical opioid use and harm in North America is well-documented, with similar issues emerging in Australia. One response is the development of tamper-resistant formulations of opioids. A potentially tamper-resistant formulation of controlled-release oxycodone was introduced in Australia in April, 2014, rapidly replacing the non-tamper-resistant formulation. Our study is the most systematic and comprehensive examination of the impact of a new opioid formulation to date, assessing the effect of tamper-resistant formulation of controlled-release oxycodone on population-level opioid use and opioid-related harm (ie, overdose, help-seeking, and treatment-seeking); and opioid use, tampering, and preference for the tamper-resistant formulation of controlled-release oxycodone compared with other drugs or formulations among sentinel populations likely to tamper with pharmaceutical opioids.

Methods
We conducted interrupted time-series analyses of opioid sales data and multiple routinely collected health datasets, followed up a cohort of people who tamper with pharmaceutical opioids before and after the introduction of the tamper-resistant formulation of controlled-release oxycodone, and analysed annual surveys of people who inject drugs. Data were collected from several Australian states: New South Wales, South Australia, and Tasmania. Meta-analyses (weighted Z tests) were conducted to synthesise across data sources providing evidence for a given indicator.

Findings
At the population level, we found reduced sales of higher strengths of controlled-release oxycodone and increased sales of other oxycodone formulations. No significant effect was observed among population-level indicators of opioid overdose, or help or treatment-seeking. Mortality data were not available for inclusion at the time of our study. Meta-analyses across sentinel populations (ie, prospective cohort, surveys of people who inject drugs, and clients of supervised injecting facilities or needle and syringe programmes) indicated reduced controlled-release oxycodone use via tampering (mainly injection), with no evidence of switching to heroin or other drug use.

Interpretation
This formulation of controlled-release oxycodone reduced tampering with pharmaceutical opioids among people who inject drugs, but did not affect population-level opioid use or harm.

Briony Larance, PhD, Timothy Dobbins, PhD, Amy Peacock, PhD, Robert Ali, MBBS, Raimondo Bruno, PhD, Nicholas Lintzeris, PhD, Michael Farrell, FRCP, Louisa Degenhardt, PhD
The Lancet Psychiatry, January 10, 2018
http://dx.doi.org/10.1016/S2215-0366(18)30003-8
http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(18)30003-8/fulltext

The effect of a potentially tamper-resistant oxycodone formulation on opioid use and harm: main findings of the National Opioid Medications Abuse Deterrence (NOMAD) study – 2018-02