Abbott Laboratories' (ABT) second-quarter profit fell 2.6% on restructuring and acquisition costs while maintaining steady sales of its Humira arthritis drug and its Xience stent.

Revenue fell short of expectations due to currency moves and patent-loss effects, and the maker of drugs and medical devices gave a cautious earnings forecast for the current quarter. As such, shares fell 2.2% premarket to $45.45.

Abbott, which reiterated its 2009 earnings target, expects third-quarter earnings of 88 cents to 90 cents a share. The mean estimate of analysts surveyed by Thomson Reuters was 90 cents.

Abbott's results have held up fairly well despite the recession as its broad product base and minor exposure to patent expirations shield it against the woes that have hit big pharmaceutical makers. But the company's Humira drug, long a driver of success, has been the focus of concern since Abbott's scaling back its forecast for full-year Humira sales growth seemed to confirm some investors' fears that prescription growth is slowing.

Abbott reported second-quarter earnings of $1.29 billion, or 83 cents a share, down from $1.32 billion, or 85 cents a share, a year earlier. Excluding items such as restructuring and acquisition costs, earnings rose to 89 cents from 84 cents. The company's April forecast was 87 cents to 89 cents.

Net sales rose 2.5% to $7.5 billion, but increased 10.5% excluding the stronger dollar's impact. A further four-percentage-point reduction was due to loss of patent protection for the anti-epilepsy drug Depakote. Analysts were expecting revenue of $7.55 billion.

Gross margin rose to 58.3% from 57.3%.

Pharmaceutical sales - Abbott's biggest business - fell 4.3% but rose 4% excluding currency effects. Humira sales rose 21% globally while Depakote tumbled 79% in the U.S. In April, Abbott called for Humira 2009 growth of 15% to 20%, versus a previous projection of more than 25%, citing market dynamics and currency rates.

U.S. stent sales more than tripled as Abbott's Xience drug-coated stent - used to prop open damaged arteries - has vaulted to a leading position in the stent market since hitting the U.S. last year.

-By Mike Barris, Dow Jones Newswires; 201-938-5658; mike.barris@dowjones.com