Updated from July 22Strong sales of Amgen's ( AMGN) treatments for rheumatoid arthritis and anemia fueled the company's second-quarter earnings growth, with the drugmaker reiterated 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. Revenue came in at $2.6 billion, up 27% year over year, and beating the $2.5 billion analyst estimate. Shares of Amgen fell 42 cents, or 0.7%, to $55.68 in premarket trading Friday. Product sales rose 27% to $2.4 billion from $1.9 billion a year ago, 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 the company's 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. 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 CEO. Going forward, the company reiterated its guidance of earnings between $2.30 and $2.40 in fiscal 2004, which is at the low end of the current Wall Street estimate of $2.40 a share.