The lead outside investigator on a crucial trial of two widely used anti-cholesterol drugs said in an e-mail message in July that Merck and Schering-Plough, the companies that make the drugs, were deliberately delaying the release of the trial results "to hide something." The companies did not release the preliminary results of the trial, called Enhance, until January, almost two years after the trial was finished. When they were released, the trial's results showed that the drugs, Vytorin and Zetia, did not work to reduce plaque in arteries. The results led a panel of cardiologists to recommend Sunday that the drugs be used only as a last resort. The new information was contained in e-mail messages to executives at Schering-Plough that were released Monday by Senator Charles Grassley of Iowa, the ranking Republican on the Senate Finance Committee. The panel has been investigating the delay in the release of the Enhance trial results. This is expected to inflame the controversy over the way that Merck and Schering-Plough handled the Enhance trial and their heavy promotion of Vytorin and Zetia. The drugs are used to lower cholesterol and are among the most widely prescribed medicines in the United States, with sales of $5 billion last year. Shares of Merck and Schering-Plough plunged Monday. The Enhance investigator, Dr. John J.P. Kastelein, also complained in July that Merck and Schering-Plough had not consulted him on the reasons for the delay and threatened to resign as the main study investigator. A spokeswoman for Schering-Plough said the messages had been presented out of context and that Kastelein's complaints had been resolved months ago. Zetia lowers cholesterol by blocking its absorption in the intestine. Vytorin combines Zetia with simvastatin, another cholesterol-lowering drug sold under the brand name Zocor. Kastelein is a Dutch cardiologist and scientist hired by Merck and Schering-Plough to conduct the Enhance trial, which consisted of images of the arteries of 720 patients taking either Vytorin - the combination of Zetia and Zocor - or Zocor alone. Because Vytorin lowers cholesterol more than Zocor alone, the companies expected that the trial would show that patients who took Vytorin had less growth of plaque in their arteries than those who took Zocor. Arterial plaque is closely correlated with heart attack and strokes. The trial ended in April 2006, and its results were initially expected in late 2006 or early 2007. The companies repeatedly delayed releasing the results of the trial, saying publicly that many of the images of the arteries were unclear and might need to be examined again. By July 2007, Kastelein was privately furious with the companies for the delays, his messages show. "Is it correct that SP has decided not to present at AHA?" he said July 6 in an e-mail message to Dr. Rick Veltri, a vice president at the Schering-Plough Research Institute, referring to the American Heart Association conference in November. "If this is the case, our collaboration is over," he wrote, adding, "This starts smelling like extending the publication for" nothing other than "political reasons, and I cannot live with that." The next day, according to the text of the messages released by Grassley, Kastelein complained that the companies seemed to be trying to slow the release of the results by including data that was not relevant and would take more time to compile. By doing so, he wrote, "you will be seen as a company that tries to hide something and I will be perceived as being in bed with you!" Kastelein did not respond to requests for comment. Rosemarie Yancosek, a spokeswoman for Schering, said, "The e-mails selectively excerpted in the letter concern an issue that Merck-Schering-Plough and - we believe, also Dr. Kastelein - consider long resolved." Dr. Harlan Krumholz, a cardiologist at Yale, said Kastelein's messages raised new concerns over the nearly two-year delay in the release of the Enhance results. "What raises concerns here is the possibility that the delay was being imposed by the companies against the wishes of the principal investigator, who should be the leader of the study," Krumholz said. "I hope that there was a good scientific explanation, endorsed by a steering committee of credible scientists at the time of the decision to delay, which explains why the public and the profession had to wait so long." On Sunday, Krumholz and three other cardiologists told an audience of more than 5,000 people at the annual American College of Cardiology scientific convention that Vytorin and Zetia should not be used except as a last resort. The two major cardiology associations seconded those recommendations on Monday, leading to a fall in shares of Merck and Schering. Merck fell $6.56, or 15 percent, to $37.95. Schering, which is smaller and even more dependent on profits from Zetia and Vytorin, fell $5.06, or 26 percent, to $14.41. On Tuesday, shares of Merck were up 1.53 percent and those of Schering-Plough were up 4.36 percent Prescriptions for the two medicines have already dipped about 15 percent since January, when preliminary results from the Enhance trial were first disclosed. Still, the drugs are widely used, with about three million prescriptions written each month in the United States alone.