S-P/Merck & Co account for ENHANCE delay

US drug majors Schering-Plough and Merck & Co have issued a time line of events accounting for the two-year delay in disclosing unfavorable data on their co-marketed cholesterol drugs Vytorin (ezetimibe and high-dose simvastatin) and Zetia (ezetimibe), claiming that problems with the quality of images used to measure the primary endpoint, carotid intima thickness, caused the wait.

The ENHANCE study, which was completed in April 2006, showed that Vytorin was no more effective than Merck's off-patent statin Zocor (simvastatin) at slowing progression of heart disease (Marketletter January 15). Between then and the disclosure, revenues from Vytorin grew to $5.0 billion a year. According to the Wall Street Journal, the chronology states that problems with the images surfaced in the 2005, prompting the firms to convene two expert panels, as well as to run small studies of new analysis methods. The drugmakers also claim that the data were blinded during the two years. The conduct of the trial is being investigated by Congress. The Food and Drug Administration has issued a statement to inform the public that it will conduct a review of the ENHANCE trial once it receives the final study results.