Strong sales of Amgen's ( AMGN) treatments for rheumatoid arthritis and anemia fueled the company's second-quarter earnings growth, with the drugmaker reiterating earnings guidance for the rest of 2004.

Amgen announced second quarter net income of $748 million, or 57 cents a share, up 23% from the $607 million, or 45 cents a share, it had a year ago.

On an adjusted basis, excluding charges related to the company's purchase of Immunex, which is how Wall Street views the company, Amgen earned $809 million, or 62 cents a share, up from $653 million, or 49 cents a share, a year ago. Wall Street expected the company to earn 59 cents a share.

Total revenue came in at $2.6 billion, up 27% year-over-year, and beating the $2.5 billion analyst estimate. Ahead of the earnings release, which came after the close of trading on Thursday, shares of Amgen rose 25 cents, or 0.5%, to $56.10.

Product sales came in at $2.4 billion, up 27% from the year-ago quarter's $1.9 billion, driven by strong sales of Aranesp, a treatment for anemia, and Enbrel, a rheumatoid arthritis treatment, which combined accounted for slightly less than half of its total sales. The company said sales of Aranesp came in at $617 million, up 78% year-over-year, while Enbrel sales came in at $440 million, up 45% year-over-year.

"The strong second quarter performance reflects our solid execution across the business in the U.S. and European markets. In Europe, Aranesp has become the market leader for anemia treatment in both chemotherapy and nephrology patients with its less frequent dosing regimen," said Kevin Sharer, chairman and chief executive officer.

Going forward, the company reiterated its guidance for EPS of $2.30 to $2.40 in fiscal 2004, compared to the current Wall Street consensus estimate of $2.40 a share.