NEW YORK (AP) — Shares of Amylin Pharmaceuticals Inc. fell Thursday following a Food and Drug Administration panel's recommendation for approval of a rival's diabetes treatment. The stock fell 72 cents, or 6 percent, to $11.33 in afternoon trading. Shares have traded between $5.50 and $35 over the past 52 weeks. On Wednesday, an FDA panel of experts recommended approval of New York-based Bristol-Myers Squibb Co.'s and London-based AstraZeneca's oral diabetes drug Onglyza, or saxagliptin. The panelists also recommended studies of heart safety after approval. The agency is not required to follow the panel's recommendation, though it normally does. Novo Nordisk's once-daily injectable drug liraglutide, which is expected to compete even more directly with Amylin's twice-daily Byetta injection, is facing a similar panel review Thursday. Wall Street expects the FDA eventually to approve both Onglyza and liraglutide. San Diego-based Amylin, along with Indianapolis-based Eli Lilly & Co. and Cambridge, Mass.-based Alkermes Inc., is developing a once-weekly version of Byetta, called exenatide LAR. The companies hope to ask for FDA approval in the second quarter. Like its potential competitors, though, that drug will face increased safety scrutiny by the agency over potential heart risks. Bristol-Myers and AstraZeneca's Onglyza got a favorable 10 to 2 vote on the heart risk issue. But the same panel unanimously agreed that the drug should continue to be studied on high-risk patients to assure safety. Novo Nordisk is likely to face the same scrutiny, as is Amylin and partners when LAR comes under review. "It is difficult to gauge FDA or the panel's willingness to accept the liraglutide cardiovascular data, but at a minimum we feel post-approval studies will be required," said Thomas Weisel analyst M. Ian Somaiya, adding that the agency could require a safety study before the drug is approved. Still, the panel decision is still too close to call, he added, and said investors should remain cautious on buying Amylin shares until a recommendation is rendered. The panel recommendations for each of these new drugs are being closely watched by Wall Street, as the proposed measures could serve to either delay approvals or possibly benefit a specific drug's chances at success on the market. Type 2 diabetes affects about 23 million adults and teenagers in the U.S. While each current and proposed Type 2 diabetes drug treats the condition by controlling blood-sugar levels, they are divided into separate classes. Onglyza is part of the DPP4 class of treatments and is expected to directly compete with Whitehouse Station, N.J.-based Merck & Co.'s Januvia, which is already on the market. Leerink Swan analyst Seamus Fernandez said he is still cautious about how soon those two drugs will compete in the market. "Given the FDA's apparent comfort with the saxagliptin application, the only obstacle to final approval may be Bristol-Myers ongoing study of saxagliptin in patients with moderate to severe renal insufficiency," he said in a note to investors. That could delay approval until 2010, he said, adding that full approval in the next month would be a surprise, based on his assumption. Meanwhile, LAR is being viewed as the key to rejuvenating Amylin's sales. It is part of the GLP-1 class of treatments, as is Byetta and Novo Nordisk's liraglutide. If approved soon, liraglutide could hurt sales of Byetta, analysts have warned.