Bristol-Myers Squibb (BMY) and Eli Lilly (LLY) both reported weaker quarterly earnings and sales on Wednesday as they struggled to stem losses from patent expirations.

Bristol earned 38 cents a share during the second quarter, down 27% year-over-year. Excluding one-time items, the drug maker earned 48 cents, matching average analyst estimates in a Thomson Reuters poll.

New York-based Bristol said sales fell 18% to $4.4 billion from $5.4 billion a year ago following the expiration of exclusive patents of its stroke medicine Plavix and high blood pressure treatments Avapro and Avalide. Analysts on average were looking for sales of $4.45 billion.

Sales of Plavix tumbled 60% to $741 million from $1.8 billion a year ago as the U.S. Food and Drug Administration began approving generic versions of Bristol’s blockbuster drug. Sales of Avapro/Avalide slipped 53% to $117 million.

“We have been preparing for the expected loss of exclusivity of Plavix and Avapro/Avalide for a number of years and I am pleased with our company’s progress as we look to the future,” Bristol-Myers CEO Lamberto Andreotii said in a statement.

Bristol-Myers weakened its GAAP fiscal 2012 earnings forecast to a range of $1.78 to $1.88 a share from an earlier $1.90 to $2.00 a share. Excluding one-time items, it sees earnings between $1.90 and $2 a share, bracketing the consensus of $1.94.

Lilly, meanwhile, reported second-quarter net income of $923.6 million, or 83 cents a share, compared with a year-earlier $1.2 billion, or $1.07 a share. Analysts were looking for earnings of 77 cents.

Revenue for the three-month period fell 10% to $5.6 billion from $6.25 billion, virtually matching the Street’s view of $5.59 billion. The decline mostly reflected the loss of patent exclusivity of Lilly’s schizophrenia drug Zyprexa.

Losses for the Indianapolis-based drug maker were partially stemmed by a 22% revenue increase in depression drug Cymbalta and double-digit improvements in Lilly’s pharmaceutical businesses in China and Japan.

"Despite the continued decline in Zyprexa sales following patent expiration late last year in most major markets outside Japan, we achieved strong growth for other products such as Cymbalta, Alimta, Forteo, Effient and our animal health portfolio,” Lilly CEO John Lechleiter said in a statement.

The pharmaceutical giant increased its fiscal 2012 non-GAAP earnings to a range of $3.30 to $3.40 a share from an earlier $3.15 to $3.30 a share and still anticipates revenue between $21.8 billion and $22.8 billion. The consensus is calling for earnings of $3.29 on sales of $22.71 billion.

Lilly is expecting more than a $3 billion decline in Zyprexa sales as it continues to compete against generic drugs, however it continues to anticipate growth from Cymbalta and Cialis.

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