Either Depomed (Nasdaq: DEPO) bulls or Depomed bears are going to feel some pain in the next week when the Food and Drug Administration makes a decision about the company's post-herpetic neuralgia (PHN) drug, DM-1796. PHN is a nerve pain that occurs after patients get shingles.

The PDUFA date for the FDA to make a decision is Jan. 30. That's a Sunday, so we'll likely hear on Friday or Monday or maybe even earlier. The PDUFA date is a goal; it's not set in stone when the agency will announce its decision.

Predicting the fate of DM-1796 seems easier than other recent FDA decisions. The drug is a long-lasting version of the extended-release formula of gabapentin, which Pfizer (NYSE: PFE) sold as a PHN treatment called Neurontin. There's really no such thing as a low-risk FDA decision, but this one is at least lower risk. Except for the extended-release technology, there isn't much that's new here.

That's in contrast to GlaxoSmithKline (NYSE: GSK) and XenoPort's (Nasdaq: XNPT) extended-release gabapentin, Horizant, which the FDA turned down as a treatment for restless leg syndrome. The agency decided potential side effects that were acceptable for epilepsy and PHN weren't acceptable for restless leg syndrome.

There are also a couple of indirect signs that DM-1796 will get past the FDA.

On a conference call last week, an analyst asked if Abbott and Depomed were discussing the label with the agency. Since there's little reason to work out the details of the label if the agency is going to reject the drug, the analyst was really asking if it seemed likely that the agency would approve the drug. CEO Carl Pelzel wouldn't bite but did say that he was confident that the agency would make a decision by the PDUFA date. While that's not quite as satisfying, it's at least a sign the FDA isn't still shooting a lot of questions at Abbott and Deopmed.

Last week, Depomed said Abbott Labs (NYSE: ABT) was refusing to launch DM-1796, which seems to point to Abbott thinking the FDA will approve the drug. It seems like Abbott would be in a better position to negotiate if the drug were rejected, so making its move now implies that Abbott thinks that won't happen.

The last two are more conjecture than solid investment theses, but with the black box FDA, that's about all you're going to get.

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Pfizer is a Motley Fool Inside Value recommendation. GlaxoSmithKline is a Motley Fool Global Gains recommendation. The Fool owns shares of GlaxoSmithKline. Motley Fool Alpha owns shares of Abbott Laboratories. 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.