Amylin Pharmaceuticals Inc., rebuffed twice in its bid for U.S. approval of a weekly diabetes drug, will meet its timetable and submit a heart-safety study to regulators by the end of 2011, its CEO said.

The San Diego-based company may finish the study early if the Food and Drug Administration allows a less complex design, CEO Daniel Bradbury said in an interview Monday at the J.P. Morgan Healthcare Conference in San Francisco.

Amylin lost about half its market value Oct. 20 after saying the FDA wanted a study assessing the drug’s heart risks, though the shares have since gained almost half of the lost value. Bydureon is a longer-acting version of the twice-daily diabetes injection Byetta sold by Amylin and Indianapolis-based Eli Lilly and Co.

A weekly drug would be more convenient for patients and help the company compete with Novo Nordisk A/S of Bagsvaerd, Denmark, the world’s biggest maker of insulin.

“We will initiate the study in the first quarter and we remain very confident that we will be able to complete the required work by the end of 2011,” Bradbury said.

Byetta, a synthetic version of a substance found in the saliva of the Gila monster, stimulates pancreas cells to produce the hormone insulin when blood sugar is high. It had worldwide sales of $796.5 million in 2009. Sales fell 18 percent in the third quarter of 2010, to $168.8 million, Lilly said on Oct. 21.

Lilly attributed the drop to competition in the U.S. and German markets. A new Novo drug, Victoza, entered the market last year. While similar to Byetta, it can be taken once a day instead of twice.

Joshua Schimmer, an analyst for Leerink Swann, said Amylin may complete and submit the heart-safety studies by the middle of this year and win approval for Bydureon by the end of the year. Bydureon revenue may reach $600 million in 2014, pushing combined revenue for Bydureon and Byetta to $965 million, Schimmer said in a Jan. 4 note to investors.

Amylin said in October it would submit the heart-safety study by the end of 2011.

Lilly markets Byetta outside the U.S. and co-markets it with Amylin in the U.S. The drug was developed by Amylin, and the technology enabling it to be used in a longer-acting form was developed by Waltham, Mass.-based Alkermes Inc. Alkermes will receive royalties of about 8 percent on Bydureon sales.