"Potential heart problems? We don't see no stinking potential heart problems" -- a paraphrase of the Committee for Medicinal Products for Human Use of the European Medicines Agency.

The committee issued a positive opinion today recommending approval of Bydureon, the once-weekly diabetes drug from Amylin Pharmaceuticals (Nasdaq: AMLN), Alkermes (Nasdaq: ALKS), and Eli Lilly (NYSE: LLY). The companies just need a rubber stamp from the European Commission, and they'll be able to start negotiating reimbursement for the drug in Europe.

The Food and Drug Administration wasn't so kind. The agency is requiring the companies to run a thorough QT study to measure the effect of the drug on heart rhythms.

This isn't the first time the EMA and FDA haven't seen eye to eye, and it certainly won't be the last. While the data that the agencies see is usually the same, the risk-benefit analysis is basically a matter of opinion. In the most extreme case, InterMune's (Nasdaq: ITMN) idiopathic pulmonary fibrosis treatment, Esbriet, only passed one of the two phase 3 clinical trials run by the company. That was good enough for the Europeans but not for the FDA.

Bydureon is extremely important to Amylin. Its twice-daily Byetta is getting beat up in the market by Novo Nordisk's (NYSE: NVO) once-daily Victoza. In the battle of needle pricks, the once-weekly formulation is the only hope of recapturing those patients.

Investors in Alkermes, which contributed the extended-release technology to allow for once-weekly dosing, are eagerly awaiting the royalties from sales of Bydureon. For larger Eli Lilly, the European approval isn't as big of a deal, but every little bit helps when you're facing a patent cliff.

Keep in mind that the results of the thorough QT study, due to be completed later this year, remain a gating event for both the U.S. and Europe. If the drug were to show a hint of heart issues, the European Commission could pull the marketing approval for Bydureon.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Motley Fool has a disclosure policy.