Use of analgesics following rescheduling of codeine in Australia: An interrupted time series analysis in the veteran population

Abstract

Background: The Australian medicines regulator, the Therapeutic Goods Administration (TGA), rescheduled all codeine-containing medicines to be available only on prescription on 1 February 2018. This study was conducted to determine whether use of analgesics changed following codeine re-scheduling to prescription only status, and whether there was a change in the use of codeine preparations and a therapeutic shift to stronger opioids or other analgesics in the Australian veteran population following the change.

Methods: Interrupted time series analysis using Repatriation Pharmaceutical Benefits Scheme (RPBS) claims data from the Australian Government Department of Veterans' Affairs (DVA) for clients with dispensing of opioid and non-opioid analgesics between January 2015 and April 2019. Trends in the monthly rate of analgesic dispensings (opioid and non-opioid) were compared for the period between January 2015 and January 2018 with the period February 2018 to April 2019.

Results: Paracetamol with codeine 8mg was the only analgesic with an increased rate of dispensing following the February 2018 codeine scheduling changes. Prior to codeine re-scheduling, the rate of dispensing of paracetamol with codeine 8mg was decreasing by 0.9% each month. Immediately after the scheduling changes, dispensing of paracetamol with codeine 8mg increased by 45% (95%CI=1.282-1.676, p<0.001) and in the fifteen month period thereafter (February 2018 to April 2019), the rate of dispensing increased by 4% each month (95%CI=1.027-1.054, p<0.001). Therapeutic shift from over-the-counter codeine products to other opioids was not observed, with no increase in the rate of dispensing of any of the other opioid (or non-opioid) analgesics following the codeine scheduling changes.

Conclusion: A significant increase in prescription use of paracetamol with codeine 8mg was observed after the February 2018 codeine re-scheduling. Therapeutic shift to stronger opioid analgesics was not observed in the study population.

Keywords: Codeine; Drug use evaluation; Medication use; Opioid; Policy change; Regulatory change; re-scheduling.