-- Tamper-resistant tablets were misused less frequently by people who inject drugs, but have little effect on population level issues linked to overprescribing, overuse, and harm of opioids.
The introduction of tamper-resistant opioid tablets does not have an effect on rates of opioid use or harms at a population level, according to a new study in The Lancet Psychiatry journal.
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 misuse.
The study is the most comprehensive analysis of the impact of tamper-resistant opioid formulations to date. It was conducted in Australia, which is experiencing an opioid epidemic, but where the policy context is less complex than in the USA.
The observational study uses data from multiple sources over a five year period during which time tamper-resistant tablets of controlled-release oxycodone, which are more difficult to crush or dissolve, were introduced in Australia. Because of the multiple policy changes in the USA that happened alongside the introduction of tamper-resistant tablets, a similar study would not have been possible in North America.
"Although the introduction of this tamper-resistant formulation resulted in less injection of that opioid among people who inject drugs, their introduction must be considered as part of a multifaceted response. This includes 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," says Dr Briony Larance, National Drug and Alcohol Research Centre, UNSW Sydney, Australia [1].
"Approximately 2.9 million Australians were prescribed an opioid in 2014, compared with an estimated 93000 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," adds Dr Larance [1].
The opioid epidemic in the USA is widely documented and similar problems in Australia are emerging, with opioid use in 2012 15 times that reported in 1992. Pharmaceutical opioids cause more than 70% 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.
However, assessing the positive or negative impact of the introduction of tamper-resistant opioids in the USA is complicated because of the multitude of responses to the opioid crisis, including prescription-monitoring programmes, sanctions against doctors found to be over prescribing, increased public awareness, and changes to clinical guidelines.
By contrast, while there was increasing concern over opioid use and harms in Australia from 2011 to 2016, no major policy changes were implemented, apart from the introduction (in 2014) of tamper-resistant oxycodone into the market, rapidly replacing non-tamper-resistant tablets.
As part of the National Opioid Medication Abuse Deterrent (NOMAD) study, the research team 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.
The introduction of tamper-resistant oxycodone was associated with a reduction in use among the cohort of people who reported tampering with the tablets to inject opioids, and there was no evidence that this cohort of people switched to other opioids.
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 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 overdose attendance, although data on fatal overdoses were not available.
The authors note that some of the datasets lacked specificity about which type of opioid was being used, which may have affected the results, but point to the strength of the study which lies in the use of multiple datasets.
Writing in a linked Comment, Dr Nabarun Dasgupta, Injury Prevention Research Center and Eshelman School of Pharmacy, University of North Carolina, Chapel Hill (NC), USA says: "Drug use has been long recognised to be an interaction between drug, individual-level influences, and social context...The NOMAD study leads us to consider whether abuse deterrence is an inherent property of the drug itself, or its intended effect lies in an interaction with social context."
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NOTES TO EDITORS:
The study was funded by Mundipharma Australia, the Australian Government and the Australian National Health and Medical Research Council.
[1] Quotes direct from authors and cannot be found in the text of the article.
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Journal
The Lancet Psychiatry