Utilisation trends of rosiglitazone and pioglitazone in Australia before and after safety warnings

BACKGROUND A see on cardiovascular diseases and bladder cancer. The changes to the patterns of rosiglitazone and pioglitazone utilisation in Australia following the timing of these various health authority warnings such as the Australian Therapeutic Good Administration (TGA), European Medicines Agency (EMA) press releases or U.S. Food and Drug Administration (FDA) is unknown. This study investigated the utilisation patterns of rosiglitazone and pioglitazone in Australia before and after warnings of major drug authorities. METHODS We evaluated rosiglitazone and pioglitazone dispensing using the Pharmaceutical Benefit Scheme (PBS) subsidised drug dispensing data for the Australian population from February 2004 to July 2012. The World Health Organisation Anatomic Therapeutic Chemical (ATC)/Defined Daily Dose (DDD) system was used to compare the drug utilisation patterns following the announcements of EMA, FDA, and TGA safety warnings, which first occurred in May 2007. The DDD/1000 population/day were examined in a series of time-series regression analysis with the drug safety warnings specified as interventions. RESULTS Rosiglitazone utilisation increased steadily from 2004 until reaching a peak at 1.96/1000 population/day in January 2007. Then rosiglitazone use decreased significantly after the initial EMA press release and FDA warning on cardiovascular risk in May 2007 (with a 15.04% average monthly decline, p-value <0.001), however use did not significantly decrease after the TGA warning or subsequent EMA and FDA warnings. Pioglitazone utilisation proceeded rosiglitazone in September 2008 and remained above 1.5/1000/day during 2009-2010. However, pioglitazone utilisation has slightly declined after the FDA, EMA, and TGA warnings related to bladder cancer. CONCLUSIONS Drug safety warnings were associated with a decrease in rosiglitazone and pioglitazone utilisation in Australia. Rosiglitazone began to decline prior to TGA warnings in December 2007, which suggests that Australian prescribers may have acted in response to scientific evidence or international safety warnings (EMA, FDA), prior to the response of the TGA. Minor effects were observed after bladder cancer warnings on pioglitazone utilisation.