Merck & Co and Schering-Plough Corp will pay $41.5 million to settle class-action lawsuits over their shared cholesterol drugs Vytorin and Zetia, the companies said on Wednesday.

The suits involved allegations arising from the Enhance clinical trial, whose results released in January 2008 raised questions about the worth of Zetia and Vytorin.

Merck and Schering-Plough, which have agreed to merge, sell the blockbuster medicines through a joint venture. Vytorin combines Zetia and an older statin drug, Zocor, into one pill.

The settlement will resolve all the class-action lawsuits that seek economic damages related to the purchase of the two drugs, the companies said. They have disclosed about 145 such lawsuits pending in federal court in New Jersey.

Merck and Schering both recorded charges related to the settlement in the second quarter. The settlement is not an admission of misconduct or liability, the companies said in a statement.

The agreement involves two settlements: one with consumers and other entities that purchased the drugs, and one with health plans. The settlement with consumers is subject to court approval; the other is not.

The Enhance study found that Vytorin was no more effective in reducing plaque in the carotid arteries than an inexpensive generic form of Zocor (simvastatin).

Sales of Vytorin and Zetia, which had become blockbuster products, plunged when results of the trial became known.

Last month, the companies agreed to pay $5.4 million to 35 states to settle allegations they delayed negative findings from the Enhance study.

Merck shares slipped 31 cents, or about 1 percent, to $29.53 in morning trading, and Schering shares were off 22 cents at $26.25, both on the New York Stock Exchange. (Reporting by Lewis Krauskopf; editing by John Wallace and Maureen Bavdek)