San Diego, USA-based group Amylin Pharmaceuticals substantially undershot general expectations for its performance in the third quarter, with net loss more than doubling after a substantial rise in revenues failed to buffer rocketing expenses.

The group posted a loss of $69.5 million dollars, or $0.65 a share, versus $34.1 million, or $0.36 a share, for the year-ago period, missing the $0.57 a share target from analysts polled by Thomson First Call by a long shot.

This dramatic rise in loss was driven by escalating expenses, which jumped to $96.2 million from $45.8 million, pushed up by a 6.2% climb in research and development costs to $37.2 million, and selling, general and administration expenses of $52.1 million versus $15 million for the prior year’s period.

Revenues soared 93% to $25.9 million, but the comparable period of last year marked the firm’s first full quarter of operations, and the results still failed to meet Wall Street expectations of $28.7 million. Product sales of $21.9 million were also disappointing, and were primarily led by turnover of the group’s flagship product, the type 2 diabetes agent Byetta (exenatide), which generated $18.1 million. Symlin (pramlintide acetate), Amylin’s other marketed diabetes drug, which helps reduce blood sugar in conjunction with insulin and received the US regulatory nod in March this year [[18/03/05c]], turned in sales of $3.8 million.

Unsurprisingly, investors shrank back on the results, which were released after the markets had closed on October 26, as reflected by a 11.27% drop in the group’s share price to $33.71 in after-hours trading from having closed the day up 1.17% at $37.99.