Merck & Co. says its first-quarter profit more than tripled despite only slightly higher sales because of much lower restructuring and merger costs.

The results beat Wall Street expectations. Merck's stock rose 61 cents in premarket trading to $36.38.

The maker of Singulair for asthma and allergies and Januvia for diabetes says net income was $1.04 billion, or 34 cents per share, up from $299 million, or 9 cents a share, in 2010's first quarter.

Revenue edged up 1 percent to $11.58 billion. That includes several billion dollars from products acquired when Merck bought Schering-Plough Corp. in November 2009 for $49 billion.

Excluding numerous one-time items, net income was $2.86 billion, or 92 cents per share.

Analysts forecast earnings per share of 84 cents and revenue of $11.38 billion. Analysts typically exclude one-time items in their estimates.

The $1.82 billion in net charges included $1.58 billion in merger-related writedowns on the value of assets and research, $126 million in restructuring costs and a $500 million payment to settle arbitration with Johnson & Johnson over rights to two drugs.

Merck raised the bottom end of its 2011 adjusted profit forecast by 2 cents, predicting $3.66 to $3.76 per share.

"It is clear that Merck's business momentum is building, and we continue to demonstrate the ongoing value of the merger," Chief Executive Kenneth Frazier said in a statement.

Sales were driven by strong performance from Singulair, Januvia, Remicade for immune disorders and other key drugs. Their growth was partly offset by lower sales of former blockbuster heart drugs Cozaar and Hyzaar, which got generic competition last year.