Tamper-proof opioids may have stopped people injecting them, but have not slowed the epidemic.

A tamper resistant, difficult to crush formulation of OxyContin was introduced in Australia in April 2014 in response to growing concerns about its contribution to an increase in opioid use and related harms.

The new National Opioid Medications Abuse Deterrence (NOMAD) study is the most comprehensive analysis of the impact of tamper-resistant opioid formulations to date.

The study used both sales and health data across Australia, as well as survey data from a cohort of 600 people who misuse pharmaceutical opioids, to measure the new formulation’s impact on population-level opioid use and opioid-related harm as well as opioid use and tampering among high risk populations.

While the study found that people who inject drugs were less likely to tamper with the tablets, the lack of any significant effect on opioid use or harms highlights the need for a multifaceted approach to opioid overuse.

The experts say this approach should include increasing the availability of non-medication approaches to chronic pain, good clinical practice in long-term opioid treatment, and harm reduction among people who use opioids outside the recommendations of their prescriber.

“Approximately 2.9 million Australians were prescribed an opioid in 2014, compared with an estimated 93,000 people who injected drugs. As a population-wide strategy to reduce harm of overuse or overprescription of opioids, the introduction of tamper-resistant formulations alone will not be sufficient to affect these outcomes,” says Dr Briony Larance, from Sydney’s National Drug and Alcohol Research Centre.

The opioid epidemic in the USA is widely documented and similar problems in Australia are emerging.

Opioid use in 2012 was about 15 times that reported in 1992, and pharmaceutical opioids now cause more than 70 per cent of opioid overdose deaths in Australia – similar rates to the USA.

In the USA, oxycodone was developed in a tamper-resistant formulation, making it harder to crush or dissolve the tablets.

Early studies suggested the tamper-resistant formulations were associated with reduced recreational use, poisonings and sales, and increased heroin use and harm.

The NOMAD study analysed a total of 17 data sources including opioid sales data, multiple health datasets, annual surveys of people who inject drugs, and a cohort of 606 people who reported tampering with opioids before and after the introduction of tamper-resistant tablets. Data from three Australian states (New South Wales, South Australia and Tasmania) were included in the study.

At a population level, the introduction of tamper-resistant oxycodone was associated with reduced sales of higher strength controlled-release oxycodone, but increased sales of lower strength oxycodone formulations.

Additionally, there was almost no effect on the introduction of the tamper-resistant tablets at the population level.

Opioid use has continued to increase at a similar rate before and after the introduction of tamper-resistant tablets. There was no effect (positive or negative) on any population-level rates of harms, such as hospital admissions, emergency department presentations or ambulance overdoses.

The study is accessible here.