FRIDAY, Jan. 25, 2008 (HealthDay News) -- The controversy surrounding the highly promoted cholesterol-lowering drug Vytorin continued Friday when U.S. health officials said they would review the medication's effectiveness, but only after final trial results were completed.
The debate began earlier this month when preliminary results of the so-called Enhance trial showed that Vytorin -- a combination of two cholesterol drugs -- had little medical benefit.
"We have not yet received a final study report and can't explain why Vytorin didn't lead to lesser amounts of plaque compared to patients treated with simvastatin alone," Dr. John Jenkins, director of the FDA's Office of New Drugs, Center for Drug Evaluation and Research, said during an afternoon teleconference.
A study released Jan. 14 by the makers of Vytorin found that the drug -- a combination of the Zocor (simvastatin) and Zetia (ezetimibe) -- may be no more effective at reducing the build-up of plaque in the arteries than Zocor alone. About 60 percent of U.S. patients who are taking Zetia now receive the drug as part of Vytorin.
The FDA expects to receive the final report on Vytorin in the next several months, Jenkins said.
"Once we receive the final study report, we estimate it will take as long as six months for us to fully evaluate the results of the Enhance study," he said. "And we will be considering whether any further action is warranted in regard to Zetia or Vytorin, and also whether this study has any impact on our approach to the approval of lipid-lowering drugs."
The Enhance trial found that although cholesterol was lowered, the pace at which artery-clogging plaques formed within vessels almost doubled in patients taking Vytorin, compared to those taking Zocor alone.
The FDA noted the trial was not designed to detect any difference in risk of heart attack or stroke between the two treatments.
Jenkins said another ongoing trial will evaluate the effect of Vytorin compared with Zocor on heart disease and stroke. Results from this trial will be available in 2011, he said.
Merck/Schering-Plough Pharmaceuticals, the makers of Zetia and Vytorin, have been criticized for not releasing the Enhance test results earlier.
"While the Enhance trial was time-consuming and took longer than originally anticipated to complete, our companies acted with integrity and good faith in connection with the trial," Thomas Koestler, president of the Schering-Plough Research Institute, said in a prepared statement released Friday.
Dr. Harlan M. Krumholz, a professor of medicine at Yale University School of Medicine, said the FDA is right to wait until all the results from the Enhance trial are in. But in the meantime, he said, Vytorin and Zetia should be limited to patients who can't tolerate cholesterol-lowering drugs called statins, such as Lipitor.
"We have enough information from Enhance to say it is not providing much evidence that this drug is delaying the progression of atherosclerosis," he said. "It raises uncertainty whether this drug produces benefits for actual patients."
"This [Vytorin] is really a second-line drug," Krumholz said. "We really should be guided by evidence, not marketing, and the evidence is really strong for statins. If lifestyles aren't sufficient to lower cholesterol, the next place they should go is statins. Only after those have failed should you go to the next step," he added, referring to Vytorin.
For more information on lowering cholesterol, visit the American Heart Association.