By a vote of ten to five, an advisory panel of the US Food and Drug Administration (FDA) has rejected an application by Merck & Co of the US to widen the indication of its cholesterol franchise.

Following positive results of the IMPROVE-IT study with 18,000 patients, the US drugmaker had sought to recommend its Zetia (ezetimibe) and Vytorin (ezetimibe and simvastatin combined) for prevention of heart attacks and stroke. The company claimed the medicines reduce the risk of “cardiovascular events” in patients with coronary heart disease.

Although some of the FDA review panel members thought the benefits of the two drugs were significant, the majority concluded that the overall reduction risk was small and limited to certain types of patients, particularly the elderly and diabetics.

The consensus was that 50 people would need to take Zetia along with a statin for seven years to prevent just one of the cardiovascular events that made up the trial's primary endpoint.

Merck said it was reviewing the drug authority’s complete response letter before determining its next course of action.

Some outside commentators said they thought the FDA’s rejection of the Merck application – it was the final instance – could dampen the outlook for an upcoming generation of PCSK9 cholesterol-reducing preparations such as Amgen’s Repatha and Sanofi-Regeneron’s Praluent.

Analysts had expected the two new drugs to benefit from the outcome of the IMPROVE-IT study, which showed that an add-on, non-statin drug can cut cardiovascular risks by delivering bigger reductions in LDL cholesterol levels.