Shares of

Amylin Pharmaceuticals

(AMLN)

were sharply higher in premarket action Tuesday, a day after the company, along with

Eli Lilly

(LLY) - Get Report

and

Alkermes

(ALKS) - Get Report

, reported positive results from a study of a long-acting release formulation of the Byetta injection in patients with type 2 diabetes.

The multidose Phase 2 study was designed to assess the safety, tolerability and pharmacokinetics of Byetta given once a week. After 15 weeks, both doses were well tolerated and the expected therapeutic blood levels of Byetta were reached. The companies also reported dose-dependent improvements in hemoglobin and weight.

The news was released after the close of regular trading Monday.

Amylin shares were jumping more than 30% to $28.56 before the opening bell. Alkermes rose 15% to $18.20, and Lilly tacked on 0.6% to $55.

In April, the Food and Drug Administration approved twice-daily exenatide under the trade name Byetta for use by people with type 2 diabetes who weren't able to control their blood sugar levels after using commonly prescribed oral medications.