VIOXX® Withdrawal and Impact on COX-2 Inhibitor Market
On September 30, 2004, Vioxx® was withdrawn from the market and warnings
about the heart risk associated with other Cox-2s followed close behind.
This analysis examines the trends in the Cox-2 market over the past two
years and how Cox-2 claimants reacted to the withdrawal of Vioxx® and
concerns about other Cox-2s.
Claimants that made claims for Cox-2 drugs through the Ontario Drug Benefit (ODB) program were identified between January 2002 and December 2004.
A time-series analysis of these claims demonstrates the trends in the market (see Figure 1).
During this time, claimants who stopped using Rofecoxib (Vioxx®) and Celecoxib (Celebrex®)
were identified and stratified into two groups; those stopping the respective drugs during January
to December 2003 versus January to December 2004. In each time period, claimants were categorized
according to whether they stopped all pain medication therapy or switched to another drug.
The proportion of claims switching or stopping therapy were compared between the two drugs and time periods (see Figure 2).
• Of the claimants stopping Vioxx® and Celebrex® during 2003, the distributions stopping all pain drugs or switching to another medication were similar between the two drugs.
• The discontinuation of Vioxx® in 2004 resulted in an increase in the percentage of claimants switching to other pain medications compared to patients who stopped using Vioxx® in 2003.
• Conversely, the opposite occurred for Celebrex®, where there was an increase in claimants who stopped Cox-2 therapy in 2004 compared to 2003.
CONCLUSION
The withdrawal of Vioxx® in 2004 resulted in fewer claimants actually stopping therapy with an increase in the number of Vioxx®
claimants switching to other types of therapy including meloxicam and Celebrex®. Self-selection of claimants stopping Celebrex® in 2004,
resulted in an increase in Celebrex® claimants re-evaluating their treatment and discontinuing not only Celebrex® but all pain drugs.
