High-dose codeine

The Therapeutic Goods Administration (TGA) has conducted an analysis of trends in the utilisation of high-strength codeine funded by the Pharmaceutical Benefits Scheme (PBS), finding a temporary spike after the up-scheduling of low-dose codeine that subsequently diminished entirely over time.

The decision to up-schedule all codeine products to prescription only was taken after evidence showed that medicines containing low-dose codeine combined with paracetamol or nonsteroidal anti-inflammatory drugs (NSAIDs) – such as ibuprofen or aspirin – were generally no more effective than other non-codeine medicines. The codeine-containing combinations were also associated with a number of health risks including addiction leading to misuse, liver damage, gastrointestinal perforations, blood potassium imbalances and respiratory depression. These risks were judged to be too high for the codeine combination products to be supplied without oversight from a doctor.

In April 2019, the TGA published an analysis of codeine supply based on industry sales data (IQIVIA). The latest analysis is based on PBS dispensing data between 2014 and 2019.

The PBS-listed medicine of interest in the TGA's latest analysis was paracetamol 500 mg plus codeine 30 mg. We found that the PBS dispensing increased by 6.5 per cent in February 2018 when all low-strength codeine products were up-scheduled from over-the-counter to prescription only. However, the increase was transitory. It diminished in the succeeding months and, by 2019, the PBS dispensing of high-strength codeine had returned to the level before February 2018.

For the first 11 months after up-scheduling in 2018, the estimated national total dispensing was 5393 kg, in comparison with a total of 5237 kg for the equivalent 11-month period in 2017. In 2019, the total dispensing was 4721 kg between January and October, in comparison with 4679 kg for the same period in 2017.

The analysis used the quantity of codeine dispensed in the PBS scripts and population estimates made by the ABS. The PBS dispensing data between 2014 and 2019 were extracted from the Australian Government Department of Health Enterprise Data Warehouse on February 26, 2020. Time series intervention analysis was used to model monthly per capita dispensing over the 70-month period. The 2017 national totals were standardised to the 2018 and 2019 populations respectively to control for population growth.

In addition to the transitory increase after up-scheduling, we found decreases in the dispensing of high-strength codeine in the months leading up to February 2018 (see Figure 1). The first was a level shift starting in August 2015 when the PBS dispensing decreased by 6.3 per cent, followed by a second level shift starting in 2017 when dispensing decreased further by 3.5 per cent. Statistical modelling did not support a linear trend over the study period, or constant level shift occurring after February 2018. The PBS dispensing did not show the large fluctuations observed in codeine wholesale data extracted from the IQVIA database.

The increased dispensing of high-strength codeine after up-scheduling was consistent with a scenario of codeine consumers switching from low-strength to high-strength products. However, the increase has not lasted beyond 2018. Moreover, the level shifts starting in 2015 and then in 2017 suggest that TGA's regulatory activities (e.g. expert advisory meetings and public consultations) have had a positive impact on the public awareness of codeine's health risks, contributing to reduced codeine consumption and harms in Australia.

Figure 1: Percentage change in monthly per capita dispensing of high-dose codeine combination products (paracetamol 500 mg plus codeine 30 mg), relative to the pre-August 2015 level, Australia, January 2014 to October 2019. Source: Australian Government Department of Health Pharmaceutical Benefits Scheme; Australian Bureau of Statistics.