Biotech giant Amgen Inc. reported an 11 percent fall in third quarter profit as it business expenses rose and sales of several leading drugs declined.

The Thousand Oaks company said late Monday its net income slipped to $1.24 billion ($1.28 per share) from $1.39 billion ($1.36) a year earlier. On a pro-forma basis, net income was $1.36 a share, exceeding the $1.27 per share average estimate by 19 analysts surveyed by Bloomberg News.

Revenue was $3.81 billion, a gain of less than 1 percent. Amgen said its top anemia drugs, Aranesp and Epogen, continued their sales declines. Rheumatoid arthritis drug Enbrel, the company’s top seller, also saw sales fall.

The company said several product recalls and higher research and development expenses raised it business costs, as did an increase in its corporate tax rate.

However, many analysts remain bullish on Amgen due to its bone drug denosumab, which was approved this year to treat osteoporosis. The company is seeking approval to use the drug for other conditions, including metastatic prostate cancer.

Shares of Amgen lost 35 cents, or less than 1 percent, to $59.60 in after-hours trading on the Nasdaq.