After the very negative Food and Drug Administration document released ahead of Johnson & Johnson (NYSE: JNJ) and Bayer's advisory panel meeting on expanding the indication for Xarelto, it sure looked like the companies were headed into the firing squad.

Instead, most of the committee came to the companies' rescue. In a 9-2 vote with one abstention, the committee recommended approving Xarelto for atrial fibrillation.

While that sounds pretty close to a ringing endorsement, the FDA pays as much -- if not more -- attention to the comments about the drug, and why committee members voted the way they do, as they do to the actual vote. Based on reports from the meeting, it sure doesn't appear that this is a strong endorsement of Xarelto.

If anything, the decision is a vote against warfarin, the current standard of treatment. The drug is notoriously difficult to obtain the correct dose for patients. Too little and it doesn't help; too much and there's a risk of internal bleeding. The drug is used as rat poison, and kills pests through that exact mechanism. Even if Xarelto isn't as effective as warfarin, the contrast in safety profiles might justify its use in some circumstances.

Keep in mind that the FDA has the final say, though, so the reviewers' opinions in the briefing documents should be taken as the starting point. Were the vote and comments enough to sway the agency's opinion? We'll know on or around Nov. 5, when the FDA is scheduled to make a decision. I think Xarelto will still get a complete response letter -- the FDA's euphemism for rejection -- but that's just a guess, based on previous experience with negative briefing documents and positive panels: Dendreon (Nasdaq: DNDN) and InterMune (Nasdaq: ITMN), for example.

Even if the FDA approves Xarelto for atrial fibrillation without a requirement to run any additional trials, I wouldn't count on Xarelto grabbing too much of the market. Boehringer Ingelheim's Pradaxa was recently approved to treat atrial fibrillation, and Pfizer (NYSE: PFE) and Bristol-Myers Squibb's (NYSE: BMY) Eliquis will likely be approved next year, considering the outstanding data it's posted to date. The atrial fibrillation market is a decent size, but if Xarelto is relegated to a third-line therapy, its fraction of the pie won't be very large.

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Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. The Motley Fool owns shares of Dendreon and Johnson & Johnson. Motley Fool newsletter services have recommended buying shares of Johnson & Johnson and Pfizer. Motley Fool newsletter services have recommended creating a diagonal call position in Johnson & Johnson. 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. The Motley Fool has a disclosure policy.