Drug makers Merck & Co. and Schering-Plough Corp. say they will pay $5.4 million to settle civil claims that the companies covered up test results that cast doubt on the effectiveness of two blockbuster cholesterol drugs.

The companies settled with attorney generals from 35 states and the District of Columbia, including West Virginia. Merck and Schering-Plough will pay back the costs of the investigation, but don't have to make other payments or admit wrongdoing or liability.

In 2008, the companies released studies showing Vytorin and Zetia, sold by the Merck/Schering-Plough Pharmaceuticals joint venture, were not more effective than an older drug at reducing plaque buildup. The testing was finished in 2006 and the companies faced criticism for not releasing the results sooner.