Merck & Co and Schering-Plough have agreed to pay $5.4m worth of legal costs to 36 US states following an investigation into the delayed release of negative results of a clinical trial for the cholesterol-lowering drug Vytorin.

During a clinical trial for the drug called Ezetimibe and Simvastatin in Hypercholsterolemia Enhances Atherosclerosis Regression (ENHANCE), Vytorin (a combination of the drug Zetia and simvastatin) was shown to be no more effective than a cheaply available generic simvastatin.

Although the trial ended in May 2006, a partial report of results was not released until January 2008 and complete results were not published until April 2009. All the while the companies continued to promote Vytorin as a leading product directly to consumers.

As part of the settlement the companies involved did not admit any guilt and instead were ordered to pay the once-off settlement of $5.4m.

The settlement also included requirements to obtain pre-approval from the US Food and Drug Administration (FDA) for all direct-to-consumer television advertisements; comply with FDA suggestions to modify drug advertising; register clinical trials and post their results; prohibit ghost writing of articles; reduce conflicts of interest for Data Safety Monitoring Boards that ensure patient safety in clinical trials and compliance with detailed rules prohibiting deceptive clinical trials.