The migraine treatment Pozen (Nasdaq: POZN) aims to commercialize globally has hit a roadblock in Europe, or at least a detour.

Desitin, the German company that licensed the drug MT400 from Pozen last year intending to market the drug in Europe, is terminating the agreement leaving Pozen to find another partner willing to sell the Chapel Hill company’s product in the European Union.

Desitin terminated the deal because the company learned that reimbursement for the drug in Germany was unlikely, Chief Commercial Officer Liz Cermak said during a conference call to discuss financial results for the fourth quarter and full year.

Migraine sufferers in the United States know MT400 by a different name and a different dose. It’s marketed as Treximet. The combination drug is Pozen’s proprietary combination of sumatriptan and naproxen sodium; this dual mechanism was developed to give superior pain relief over drugs that offer just one mechanism of relief.

Pozen partnered with GlaxoSmithKline (NYSE:GSK) on the drug and the pharma giant holds U.S. commercialization rights. But Pozen still has rights to market the drug in the rest of the world and the company has been seeking partners to do so. Last May, Desitin licensed the drug aiming to sell it in the 27 European Union countries as well as Switzerland and Norway.

Combination migraine products are on a “do not reimburse list” in Germany. While that was known at the time the Desitin licensing deal was struck, Cermak told WRAL Tech Wire that Desitin hoped additional clinical data would overcome reimbursement hurdles. Cermak said the German pharma has been advised that MT400 reimbursement in Germany is unlikely. While Desitin could still try to sell the drug elsewhere in Europe, the German market represented Desitin’s biggest commercial opportunity. Having losing that, Desitin decided to end the deal. Desitin gave Pozen written notice of the termination on Feb. 27. The deal will end 90 days from that notice.

The only other international licensing deal Pozen has for MT400 is a 2011 agreement with Johnson & Johnson (NYSE:JNJ) subsidiary Cilag. That agreement covers four Latin American countries. But commercialization in Europe, a much larger drug market, remains up in the air.

“I can’t really say for sure,” Cermak said of Pozen’s plans for MT400. “It just won’t be marketed by Desitin.”

Cermak left open the door to finding another European partner. While another company would encounter the same reimbursement roadblock in Germany that stopped Desitin, Germany could be less of a focus for a pharma whose main footprint emphasizes a different part of Europe. Cermak said Pozen continues to look for MT400 partners at the same time it is seeking partners for the combination aspirin treatment it has been developing.

Pozen no longer draws royalty revenue from GSK’s U.S. Treximet sales. In 2011, Pozen sold those rights to Canadian pension fund CPPIB Investment for $75 million. That money was intended to support Pozen’s program developing forms of aspirin that are safer on the stomach. A new drug application for this safer aspirin is now expected to be filed with the Food and Drug Administration in the second quarter. The company expects to land a partner for this drug this year.

Finding a European partner for MT400 represents an opportunity to shore up Pozen’s revenue at a time when U.S. sales of arthritis drug Vimovo have been flat. That product is marketed by drug partner AstraZeneca (NYSE:AZN). While the United States represents the world’s largest drug market, Pozen CEO John Plachetka expressed to analysts frustration that despite AstraZeneca’s marketing efforts, Vimovo’s U.S. sales have been slow to grow. He said he expects Vimovo’s sales growth will be driven by drug launches in the rest of the world.

Vimovo holds at least one crucial marketing advantage over MT400. Vimovo is already approved for reimbursement in Germany, among other countries.