OBJECTIVES: Oxycodone controlled-release (CR) and oxymorphone extended-release (ER) are commonly prescribed, long-acting opioids, approved for twice-daily dosing.   We compared Daily Average Consumption (DACON) for oxycodone CR and oxymorphone ER before and after the introduction of reformulated oxycodone CR. METHODS: This was a retrospective claims database analysis using pharmacy claims from the MarketScan® database during January 2010 through March 2011. The Interrupted time series analysis was used to evaluate the impact of the introduction of reformulated oxycodone CR on DACON of both drugs. RESULTS: Before the introduction of reformulated oxycodone CR, the mean DACON for oxycodone CR was higher than the mean DACON for oxymorphone ER in both highest and all lower strengths pairs by 0.51 and 0.46 tablets, respectively.  After the introduction, the difference in mean DACON between the two drugs became 0.45 tablets for the highest and 0.40 tablets for the lower strengths.     Interrupted time series results demonstrated that the immediate and overall impact on DACON of the reformulated oxycodone CR was minimal, while there were no changes in the DACON for oxymorphone ER as a result of the introduction. The estimated difference in average DACON for oxycodone CR decreased by 0.1 tablets or 3.7% (P <0.001) 6 months after the new formulation was introduced. CONCLUSIONS: Mean DACON was higher for oxycodone CR compared to oxymorphone ER by 0.4 tablets per day for all dosage strengths for the entire study period.  After the introduction of reformulated oxycodone CR, the DACON for oxycodone CR was slightly mitigated; however, there was a minimal impact on the mean difference between oxycodone CR and oxymorphone ER.