The San Diego-based company reported a loss of $64.8 million for the quarter ending June 30, or 47 cents a share, compared with a loss of $45 million, or 34 cents a share, in the same quarter of 2007.

Analysts had expected a loss of about 49 cents a share.

Revenue rose about 13 percent to $222 million. Sales of Byetta, which is administered twice daily, were $177.5 million, up about 17 percent.

The company reported its results after the market closed. Its shares rose 85 cents, or 3.3 percent, to close at $26.60. In after-hours trading, they were down 30 cents.

Byetta, which helps control blood sugar in type 2 diabetics while also helping them with weight loss, has been on the market for more than three years. It has been prescribed for about 1 million patients, said Amylin Chief Executive Daniel Bradbury.

At a time when regulators and patients are defining efficacy of diabetes medications that have a strong safety profile, meaning they don't have a high incidence of causing hypoglycemia or exacerbating cardiac risks, Amylin's Byetta is in a favorable position, Bradbury said.

As the company and its marketing partner, Eli Lilly and Co., continue with an expanded marketing and sales effort, several clinical trials for a once-a-week version of Byetta are moving ahead, he said.

After one positive clinical trial for weekly Byetta, known as exenatide LAR, two more clinical trials comparing the drug against other products are enrolling patients, Bradbury said.

A fourth trial, using exenatide alone, will begin later this year, he said.

The company plans to file for regulatory approval of the once-weekly drug by mid-2009.

“A medicine such as Byetta, which provides powerful, durable glucose control with progressive weight loss and other potential benefits, is uniquely poised to take advantage of the market's growing appreciation for the benefits of our novel therapies,” Bradbury said.

Terri Somers: (619) 293-2028; terri.somers@uniontrib.com