Vytorin Risks Debated in Medical Journal

The full data for that trial were presented at the annual meeting of the American College of Cardiology in late March. An expert panel at the meeting recommended doctors avoid prescribing Vytorin and revert patients to statins, traditional cholesterol lowering drugs.

Per the recent concern over incidence of cancer, Credit Suisse analyst Catherine J. Arnold called the New England Journal of Medicine Editorial on Tuesday -- the most critical published perspective -- an important barometer to the reaction.

"This article takes the position that although the cancer analysis by the Oxford epidemiologist is credible, you still don't conclusively know whether Vytorin truly poses any cancer risk and is a variable that will have to be monitored," writes Aronld. "The tone and arguments of the article were balanced and we see that as a positive vs. investor fears."

In their editorial, the group of M.D.s and Ph.D.s -- Jeffrey Drazen, Ralph Agostino, James Ware, Stephen Morrissey and Gregory Curfman -- conclude that "Physicians and patients are unfortunately left for now with uncertainty about the efficacy and safety of the drug,"

Shares of Merck were down 2.5%, while Schering-Plough stock was up 1.9% in recent trading Tuesday.