Beleaguered biotech giant Amgen Inc. on Thursday reported a surprisingly steep drop in sales of its main anemia product line, raising doubts about the company’s growth prospects, the Los Angeles Times reports.

But the Thousand Oaks-based firm’s profit remained substantial on stronger-than-expected sales of other products.

Revenue increased 3% during the second quarter to $3.7 billion, versus $3.6 billion last year. Profit rose 2% to $1.3 billion, compared with $1.2 billion in the second quarter of 2006.

Domestic sales of Amgen’s top-line product, Aranesp, which boosts levels of oxygen-carrying red blood cells, were $578 million, in contrast to $713 million in the second quarter last year, an almost 20% decrease.

Christopher Raymond, biotech analyst at Robert Baird & Co., said the news highlighted the serious problems facing the company. The earnings “were not great,” he said. “There remains significant pressure and they may not have yet hit bottom.”

Several recent studies have raised questions about the safety of Aranesp and its shorter-acting predecessor Epogen in some patients and dosages.

This spring a Food and Drug Administration advisory panel recommended that the agency change the drugs’ labels and lower recommended dosages for some patients.

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