Merck reported second-quarter earnings on Tuesday that exceeded analysts' expectations, yet revenues fell as key drug sales tumbled sharply.
The health-care company's shares rose before the opening bell, following the news.
Earnings excluding items decreased to 83 cents per share from $1.05 a share in the year-earlier period .
Revenue eased to $11.01 billion from $12.31 billion a year ago, with the company saying second quarter pharmaceutical sales fell by 12 percent.
Analysts had expected the company to report earnings excluding items of 83 cents a share on $11.22 billion in revenue, according to a consensus estimate from Thomson Reuters.
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Like other big pharmaceutical companies, Merck has struggled to mitigate the financial impact of patent expirations of some of its most popular remedies, including asthma drug Singulair.