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A study of Australia’s wastewater shows a significant decrease in oxycodone levels, suggesting changes to prescription policies are making a difference.
Oxycodone, a potent opioid indicated for acute and cancer-related pain, accounts for most of the prescribed Schedule 8 opioids in Australia. There has been a significant increase in oxycodone dispensing; however, much of this increase has occurred among lower doses (< 50 oral morphine milligram equivalents per day). There is a national concern that increasing use has driven higher rates of misuse and fatal overdose. The policy challenge lies in allowing the legitimate medical use of oxycodone for pain management while preventing its misuse and associated health risks.
In February 2018, the Australian Therapeutic Goods Administration (TGA) introduced several changes to reduce prescription opioid misuse that included a nationwide real-time prescription monitoring (RTPM) program. In 2019, the National Opioid Analgesic Stewardship Program provided hospitals with guidelines and tools for opioid management and the National Prescribing Service (NPS) sent letters to high-prescribing clinicians, which was followed by a 5.6% reduction in prescriptions. In 2020, oxycodone was provided in smaller packages (10 to 20 tablets) along with warning labels, and in 2022, new guidelines were published to improve acute pain management and reduce opioid-related harm.
Our study evaluated the effects of these changes in oxycodone regulations and policies using wastewater-based epidemiology. Based on population data, we estimated community oxycodone consumption by measuring levels of noroxycodone, an oxycodone metabolite, in influent wastewater samples using liquid chromatography‒mass spectrometry. We collected nearly 7000 samples from more than 50 locations across Australia over a seven-year period that included periods before and after the implementation of stricter oxycodone regulations. One week of samples was collected every four months from various urban and rural locations across Australia that covered over 50% of the population.
The analysis revealed a significant 52% increase in oxycodone consumption nationally from 2017 to mid-2019 and a significant reduction of 45% in oxycodone levels thereafter. The trends in each of the states and territories matched the national pattern, suggesting that the tightened regulations have reduced oxycodone misuse similarly in each state or territory.
It is important to note that the wastewater data is an aggregate measure of community consumption, and so cannot distinguish between oxycodone that has been prescribed and oxycodone that has been diverted, is illicit, or counterfeit. Additionally, changes in opioid use from oxycodone to other prescription opioids were not captured. It is also difficult to directly connect changes in the trend to the effects of specific policy changes as public attitudes towards oxycodone and other prescribed opioids may also have contributed to their decreased use. Increased media coverage of the opioid crisis in America may have made Australians more cautious about using prescribed opioids.
Despite these limitations, the study demonstrates the potential of wastewater-based epidemiology as a valuable tool in public health surveillance that offers near-real-time data on drug consumption trends to inform policy and evaluate public health interventions.
Our study has several important implications for public health policy and practice. Firstly, the reduction in oxycodone levels in wastewater suggests that the regulatory changes have been effective but ongoing monitoring is needed to ensure sustained compliance and to detect any emerging new trends in opioid misuse, such as the use of more potent opioids (new fentanyl and nitazene analogues).
We recommend that government and health services continue to support and expand wastewater-based programs to monitor population prescription drug use. This approach can be applied to substances that have legal and/or illegal uses to provide a comprehensive picture of community drug use. It can identify the need for targeted education and intervention programs to address the underlying causes of opioid and other drug misuse, such as chronic pain management and mental health support.
Rory Verhagen is a Research Fellow at the Queensland Alliance for Environmental Health Sciences, the University of Queensland. He has a keen interest in wastewater-based epidemiology, aiming to enhance our understanding of population-wide chemical exposure.
Wayne Hall is Emeritus Professor at the National Centre for Youth Substance Use Research (NCYSUR) at the University of Queensland.
Jason Connor is a Professor of Clinical and Health Psychology in the Discipline of Psychiatry and Founding Director of the National Centre for Youth Substance Use Research at the University of Queensland.
Cobus Gerber leads the Population Health Chemistry group within the Clinical and Health Sciences Unit at UniSA. His research involves developing analytical chemistry methods to measure various substances in wastewater. The results are used to determine the scale of population exposure to compounds with harm potential. This work contributes towards the National Wastewater Drug Monitoring Program. He serves on the advisory panel of the Drug and Alcohol Services of South Australia and also the SA Drug Early Warning System.
Phong Thai is an Associate Professor and ARC Mid-Career Industry Fellow at the Queensland Alliance for Environmental Health Sciences (QAEHS). His key research interest is the expansion of wastewater-based epidemiology to determine community consumption and exposure to a range of illicit and licit drugs, including tobacco and alcohol.
Ben Tscharke is a Senior Research Fellow at the University of Queensland where he leads the National Wastewater Drug Monitoring Program. His research involves testing wastewater to estimate community consumption of illicit drugs and pharmaceuticals as well as the occurrence of emerging contaminants.
The statements or opinions expressed in this article reflect the views of the authors and do not necessarily represent the official policy of the AMA, the MJA or InSight+ unless so stated.
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And a whole lot more tapentadol… perhaps less bad but still a concern?
Over the last 5 years too there has been a massive increase in Medical Cannabis prescriptions and the most common reason is chronic pain according to the TGA. Has any analysis of contemporaneous cannabis products for the sample period.