Johnson & Johnson (NYSE: JNJ) and Bayer must feel like they're headed in front of a firing squad after reading the Food and Drug Administration documents released ahead of their advisory committee meeting tomorrow.

Xarelto is already on the market to prevent blood clots after knee or hip replacement surgery, but it has competition from Sanofi's (NYSE: SNY) Lovenox and generic versions of Lovenox from Momenta Pharmaceuticals (Nasdaq: MNTA) and Novartis (NYSE: NVS). The atrial fibrillation market is a lot more appealing since it's hard to optimize the dose of the current standard of care, warfarin, and there are nasty side effects when the patient is given too much.

The briefing document that the FDA sends to the panel members was about as negative as I've ever seen. This quote from the document sums it up about as well as I could: "There is insufficient information about the drug to determine whether it is safe for use with its proposed labeling."

Tomorrow, the roles will be reversed, and the panel of outside experts will tell the FDA what they think of the data to support Xarelto's use in atrial fibrillation. Is there something that the panel could say that would change the FDA's mind? Sure, but it would likely take a unanimous vote from the panel, and even then, the FDA doesn't have to take the panel’s advice. Short of the doctors jumping up on the table in their suits and ties and demanding approval of the expanded indication, I can't see how the FDA could approve the drug on or around Nov. 5.

Sending Johnson & Johnson and Bayer back to the drawing board would be a huge win for Boehringer Ingelheim's Pradaxa, which is already approved to treat atrial fibrillation, and Pfizer (NYSE: PFE) and Bristol-Myers Squibb's (NYSE: BMY) Eliquis, which has posted outstanding data and is headed to the FDA's desk shortly.

Check back Friday for a shot-by-shot report from the panel meeting. If you add Johnson & Johnson to My Watchlist, the Fool's free watchlist service, you'll have an easy way to find the article. Click here to get started.

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 Momenta Pharmaceuticals and Johnson & Johnson. Motley Fool newsletter services have recommended buying shares of Johnson & Johnson, Pfizer, Momenta Pharmaceuticals, and Novartis. 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.