Since there are several other such meds being developed by other drugmakers, including Lilly, the results raised questions not only about regulatory approval, but the ability of Bydureon to establish a needed edge.

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That opens the sexual-dysfunction playing field to potential competitors, including Eli Lilly (nyse: LLY - news - people) and Bothell, Wash.

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Diagnostic tests to predict who will benefit have emerged for other expensive drugs, including Eli Lilly's Erbitux and Amgen's Vectibix, but not for Avastin.

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