Merck & Co's stock enjoyed a boost yesterday after it revealed it has been given permission to continue a late-stage trial of its cholesterol buster Vytorin.

The Whitehouse Station, New Jersey-based firm must have a breathed a sigh of relief when the Data Safety Monitoring Board issued a green light for the Phase III IMPROVE for a second time, having found no significant safety concerns raised by the data.

After an earlier planned review of data last year, the Board, rather unusually, said it would undertake a second interim analysis at a later date, which had led to some concerns that there may be issues that could lead to the trial being halted, according to media reports.

However, it seems these fears are unfounded at this point, as the18,000-plus patient study - which is designed to determine whether Vytorin is more effective at reducing the risk of heart attack, stroke and death in patients with heart disease than simvastatin alone - has been cleared to conclude.

The drugmaker said the trial should finish in September next year, and it will no doubt be hoping for a positive outcome to prove the benefits of Vytorin - a combination of the generic simvastatin and the still-patented Zetia (ezetimibe) - and breathe a little new life into its heart franchise.

Citi Investment Research analyst Andrew Baum, however, expressed doubt in a research note the final analysis will show Merck's drug is more effective than generic competition, according to the Associated Press.