US regulators have rejected Merck & Co’s request to expand the use of its cholesterol busters Zetia and Vytorin.

Both are currently approved in the US for use alongside a healthy diet to reduce elevated low-density lipoprotein cholesterol in patients with hyperlipidaemia. 

The drugs giant is seeking to widen their treatment scope to include the reduction of cardiovascular events, including non-fatal stroke and heart attack, in patients with coronary disease.

But the US Food and Drug Administration has issued the firm with a Complete Response Letter turning down the applications, details of which hasn’t been revealed at this time.

The move follows a recommendation last year by an FDA advisory committee rejecting the claim that Vytorin cuts the risk of heart cardiovascular events in patients with heart disease.

Merck said it is currently reviewing the letter and will determine the next steps.