KENILWORTH & WHITEHOUSE STATION, N.J. The results of the ENHANCE study were announced by Merck and Schering-Plough, and the results were not favorable for the companies’ joint drug Vytorin. The results showed that the drug did not work better than older, less expensive generic drugs in blocking plaque buildup in the carotid arteries, according to published reports.
Vytorin is a combination of two drugs: Zetia, by Schering-Plough, and Zocor, also known generically as simvastatin, by Merck. The two companies split the revenues.
The study, sponsored by the companies, focused on patients with a predisposition to high cholesterol. The 720 people who took part were then given the largest dose of Vytorin over two years and their carotid arteries were examined. Researchers found “no statistically significant difference” in plaque buildup between those on Vytorin or simvastatin, the companies said. If a carotid artery gets blocked, blood supply to the brain will be cut, leading to a stroke.
Though Vytorin lowered cholesterol levels significantly more than generic Zocor, that didn’t translate into other hoped-for health benefits. Patients getting Vytorin had more plaque buildup in their arteries—leading to an increased likelihood of cardiac complications—though the differences between the two groups were small and may have stemmed from chance, the study found.
Zetia, unlike statins Zocor and Pfizer's Lipitor, blocks the absorption of cholesterol in the digestive tract while statins reduce production of cholesterol in the liver. No studies have yet shown Zetia or Vytorin are able to cut the risk of heart attacks and strokes.
Merck and Schering-Plough have said that they do have three additional studies on Vytorin under way, involving more than 20,000 patients, that may resolve those issues, according to reports. To get U.S. marketing approval, the companies needed only to show it lowered LDL, or “bad cholesterol,” a standard measure for cholesterol drugs.
Schering-Plough spokesman Lee Davies said because the Vytorin study concentrated on a rare population of patients who already suffered from extremely high artery-clogging LDL cholesterol, there was still no definitive answer regarding whether the drug improved outcomes. Because patients had such high cholesterol levels, it may have been difficult to show a change in arterial thickness, he said.
“It was never intended to be a definitive study on outcomes,” he said. “They both started at incredibly high LDL levels, so the patients were not brought to goal. If they were brought to goal, they might have had different outcomes.”
The study also found a “significant difference” in LDL cholesterol among Vytorin patients and those on Zocor, with 58 percent reduction in Vytorin patients compared with 41 percent on Zocor, according to the company’s statement.
The new studies’ results are expected in 2011 and some doctors believe that these studies will be positive for Vytorin.