Changes in Australian prescription opioid use following codeine rescheduling: A retrospective study using pharmaceutical benefits data (2019)

Purpose: In February 2018, Australia up-scheduled the 'weak' opioid codeine to a prescription only medication. This study aimed to analyse the change in prescribing trends for codeine and other commonly prescribed opioids in Australia following this policy change to determine if removal of over-the-counter codeine resulted in an increase in opioid prescribing.
Methods: Data was obtained through the Australian Government Department of Human Services statistics website, and contained monthly data about subsidised national prescription numbers for codeine, oxycodone, oxycodone-naloxone, tapentadol, tramadol, morphine, and fentanyl, from January 2016 to December 2018. Segmented linear regression accounting for autocorrelation was used to assess the effect of codeine rescheduling on the supply trends of these opioids.
Results: Rescheduling codeine to remove over-the-counter (non-prescription) supply does not appear to have had an immediate effect on the prescription rates of codeine, and there is no significant change in these rates in the months following. Analysis of data showed decreasing trends for codeine and most other schedule 8 prescription opioids, with no increase in any prescribed opioids associated with codeine up scheduling.
Conclusions: Despite concerns, substitution of over-the-counter codeine with higher strength prescribed codeine has not been observed at a population level, nor has a shift to other prescribed opioids occurred. Overall, opioid prescribing in Australia has been decreasing since 2016, both for strong and weak opioids.