U.S. net sales decreased 44% to $2.0 billion in the quarter compared to the same period a year ago. International net sales increased 6% to $1.9 billion.
Gross margin as a percentage of net sales was 72.3% in the quarter compared to 75.2% in the same period a year ago.
Marketing, selling and administrative expenses decreased 1% to $994 million in the quarter.
Advertising and product promotion spending decreased 3% to $189 million in the quarter.
Research and development expenses increased 2% to $930 million in the quarter.
The effective tax rate on earnings before income taxes was 7.6% in the quarter, compared to 26.9% in the first quarter last year.
The company reported net earnings attributable to Bristol-Myers Squibb of $609 million, or $0.37 per share, in the quarter compared to $1.1 billion, or $0.64 per share, a year ago.
The company reported non-GAAP net earnings attributable to Bristol-Myers Squibb of $679 million, or $0.41 per share, in the first quarter, compared to $1.1 billion, or $0.64 per share, for the same period in 2012. An overview of specified items is discussed under the "Use of Non-GAAP Financial Information" section.
Cash, cash equivalents and marketable securities were $5.8 billion, with a net debt position of $2.1 billion, as of March 31, 2013.
"The first quarter was a good start to an important year in which our focus will be on the growth of existing brands, the execution of new launches and the continued delivery of a diverse and sustainable pipeline," said Lamberto Andreotti, chief executive officer, Bristol-Myers Squibb. "So far this year, we have launched Eliquis in several markets around the world, have begun working with AstraZeneca to bring Byetta and Bydureon to patients outside the U.S., and have been preparing for the presentation of key clinical data across our pipeline."
About Bristol-Myers Squibb
Bristol-Myers Squibb is a global biopharmaceutical company whose mission is to discover, develop and deliver innovative medicines that help patients prevail over serious diseases.