Vytorin Study to Get FDA Review
Medical Mystery: Why Did Vytorin Cut Cholesterol but Not Plaque?
Jan. 25, 2008 -- The FDA says it will explore the medical mystery of why Vytorin cuts cholesterol but doesn't seem to reduce plaque in the arteries.
Vytorin is a combination of two different types of cholesterol-lowering drugs: Zetia, which blocks cholesterol absorption in the gut, and Zocor, one of the statin drugs that slows cholesterol production. Other statins include Crestor, Lescol, Lipitor, Mevacor, and Pravachol.
Zetia increases the cholesterol-lowering effects of statins. But preliminary results of a study by the companies that make and sell Vytorin were surprising.
As expected, patients who took Vytorin had lower levels of bad LDL cholesterol than did patients who took Zocor alone. But Vytorin patients did not have any less plaque in their arteries than those who took Zocor. In fact, they had slightly more.
That mystery is troubling to the FDA. Because lower LDL cholesterol is strongly linked to lower risk of heart attacks and stroke, the FDA approves drugs that can safely lower cholesterol. Even so, drugmakers must prove their products actually prevent heart disease before they can say this on the drugs' labels.
So why didn't Vytorin's superior ability to cut LDL cholesterol translate into superior ability to cut plaque? That's what the FDA wants to know, John Jenkins, MD, director of the FDA's Office of New Drugs, said in a news conference.
"We have not received the final study report and cannot explain why the lower LDL did not lead to lower amounts of plaque," Jenkins said. "Once we fully review the data, we may consider whether any further action is required, and whether this has any effect on our way of approving cholesterol-lowering drugs."
Jenkins quickly added that the FDA does not expect to change its longstanding policy of approving drugs that safely lower LDL cholesterol. All of the statin drugs were initially approved on this basis. All but Crestor -- a newer statin that is completing such studies -- eventually were shown to reduce the risk of heart attack and stroke.
Jenkins said it would take the drug companies Merck and Schering-Plough -- which jointly market Vytorin -- two or three months to get the study data to the FDA. After that, he said, it will take the FDA up to six months to review the data.