The drugmakers said in a statement that patients taking Byetta have shown "very rare case reports of pancreatitis with complications or with a fatal outcome." The companies added that diabetes patients are already at increased risk of pancreatitis compared with healthy patients.
The FDA announcement updated an October alert about 30 reports of Byetta patients developing the ailment. Regulators stressed that patients should stop taking Byetta immediately if they develop signs of acute pancreatitis, which can cause nausea, abdominal pain and potentially deadly complications.
More than 700,000 patients worldwide have used the injectable drug since it was launched in June 2005. It is marketed for patients with type 2 diabetes by San Diego-based Amylin and Eli Lilly.
Shares of Amylin Pharmaceuticals fell $5.59, or 16.3 percent, to $28.62 in afternoon trading, while Indianapolis-based Eli Lilly dipped 80 cents to $47.98.