Ellen Phiddian
Cosmos science journalist
Oxycodone use in Australia nearly halved after a policy change, according to a new study.
The study, published in Addiction, uses wastewater monitoring data to find that use dropped 45% after a series of regulations around prescribing were introduced.
The data comes from the National Wastewater Drug Monitoring Program, which samples sewage at treatment plants in several states to look for digested drugs.
Opioids like oxycodone are prescribed to treat pain, but they carry risks of addiction and death from overdose. According to government figures, 3 people die each day in Australia from opioid-related harm.
In early 2018, the Therapeutic Goods Administration (TGA) started a regulatory group on opioids, aiming to advise prescription of opioids.
A suite of regulatory moves followed in all states and territories from 2018-2020. In November 2019, the National Prescribing Service launched an initiative around opioid prescriptions, which included moves like reducing package size and adding labels to opioids, providing training, and sending alerts to high-prescribing clinicians.
In this study, the research team analysed wastewater collected by the drug monitoring program between 2017-2023.
“Most of our wastewater collection is done by the wastewater treatment plant operators, which we are really grateful of,” lead author Dr Rory Verhagen, a researcher at the University of Queensland, tells Cosmos.
The plants collect samples of roughly 100 millimetres automatically, several times an hour, add preservatives to stop degradation, and then ship the sample bottles to university labs for analysis.
Using a technique called liquid chromatography-mass spectrometry, the team examined 6,999 samples from more than 50 Australian wastewater treatment plants.
They looked for oxycodone and noroxycodone, which is a molecule oxycodone breaks down into when it passes through the body.
The researchers found that oxycodone use increased from April 2017 to August 2019, rising from 78 milligrams per 1,000 people per day to 120mg at its peak.
But then it dropped dramatically, bottoming out at 65mg per 1,000 people per day in December 2020. This is a decrease of 45%.
From there, oxycodone use increased very slightly over the next 3 years, being 2.4% higher in April 2023 than it was in 2020.
The researchers say that this drop mirrors the introduction of prescribing regulations.
“I was not really surprised to see it going down,” says Verhagen.
“That it went down by 45% that was quite surprising, but a good result.”
Verhagen says that public attitudes to oxycodone and other prescribed opioids may also have contributed to the decrease.
“It’s hard to measure, obviously, but I think the decrease was part of public opinion,” he says.
“People are more aware that opioids might be a risk due to all the media and seeing what’s happened in America.
“So people that are getting prescribed opioids are for pain relief but are told ‘if you don’t have severe pain, you don’t have to take it’, are maybe not taking it because they know the dangers of using opioids.”
The national monitoring program has also found that fentanyl use rates dropped in a similar way to oxycodone, while heroin rates have fluctuated.
Verhagen says that some of the prescription regulations were aimed at all prescribed opioids, including fentanyl.
“Fentanyl is probably also captured in some of these changes and therefore following a similar pattern as oxycodone,” he says.
“However, heroin is an illicit opioid. It’s not a prescribed medicine for pain relief, and this probably why this is following a different consumption program.”
The National Wastewater Drug Monitoring Program is continuing to track oxycodone, heroin, and fentanyl rates, as well as looking for newer synthetic opioids.
“Colleagues of mine are looking into a whole array of different prescribed opioids in wastewater, and more recently, also into illegal nitazines, which are these synthetic opioids of concern due to their high potency,” says Verhagen.
“There’s still work in this space to be done.”
