POZEN (Nasdaq: POZN) just got tripped up by a bunch of kids. The timing couldn't have been worse.

The company announced in a regulatory filing yesterday that the Food and Drug Administration had informed its marketing partner GlaxoSmithKline (NYSE: GSK) that the companies' migraine drug Treximet didn't qualify for a pediatric patent extension.

The FDA grants six months of additional exclusivity for drugmakers that test their products on children. The drug doesn't even have to work on kids; the drugmakers just need to make a valid attempt to see how the drug works in children.

It seems as though Galxo and POZEN's attempt wasn't valid enough, since the FDA wasn't willing to accept the clinical study data.

Unfortunately there's no time to fix the problem before the regulatory exclusivity expires on April 15. Pozen has three patents on Treximet that expire in either 2017 or 2025, but four generic-drug makers -- Par Pharmaceutical (NYSE: PRX), Mylan (Nasdaq: MYL) subsidiary Alphapharm, Teva Pharmaceuticals (Nasdaq: TEVA), and Dr. Reddy's Laboratories (NYSE: RDY) -- have challenged those patents.

Last year, Teva settled with POZEN, but the other three are still waiting to hear about the patent infringement case that a judge heard the arguments for in October.

POZEN believes that Par was the first to file an application to market a generic version of Treximet, which would give Par the right to launch the drug in April even if the judge hasn't made a decision by then.

If Par were to do an at-risk launch and the judge later determine the patents are valid, POZEN could recover monetary damages, but that's clearly not as ideal as just stopping the launch with a pediatric extension.

After the kid-induced faceplant, we can only hope that the judge doesn't kick POZEN while it's down.

GlaxoSmithKline and Dr. Reddy's Laboratories are Motley Fool Global Gains picks. The Fool owns shares of GlaxoSmithKline and Teva Pharmaceutical Industries. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.

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