BOSTON ( TheStreet) -- Some thoughts, comments and notes in advance of tomorrow's FDA advisory panel meeting to review Vivus' ( VVUS) weight-loss drug Qnexa:

I was asked on Twitter yesterday for my prediction on the outcome of the panel vote on Qnexa. I believe the panel will vote to recommend Qnexa's approval. I'm forecasting a mixed/close vote. This will not be a landslide victory for the drug.

I conducted a quick poll of 20 sources last night -- biotech hedge fund managers, buyside analysts and healthcare brokers -- asking them the same question. The result: 17 votes predicting a positive Qnexa vote, three votes believing the panel will go against the drug.

I'm live blogging Thursday's FDA panel in its entirety. I'll kick things off around 7:45 am EDT, the panel gets underway at 8 am and should wrap up in mid-to-late afternoon. Sign up below if you want an email reminder.

Judging by the rise in the stock prices of Arena Pharmaceuticals ( ARNA) and Orexigen Therapeutics ( OREX), what's good for Vivus might also be good for its obesity drug competitors. That may change depending on the discussion and debate at tomorrow's panel meeting.

Trading in Vivus shares will be halted tomorrow. That leaves traders to play with Arena and Orexigen. It will be interesting to see what level of volatility we get in those stocks as the panel progresses.

I haven't spoken to Vivus in front of tomorrow's panel but the company looks well prepared to tackle the safety concerns and questions that have cropped about Qnexa, judging by the printed agenda. Vivus has five speakers presenting Qnexa data to the advisory panel, including outside experts to discuss neuro-psychiatric safety, pregnancy risks, and risk management plans, including a proposal for a post-approval study to assess cardiovascular outcomes in patients treated with Qnexa.

These safety-related issues are going to be the hot-button topics tomorrow, so Vivus looks ready to make its case. I've covered a lot of FDA advisory panels in my days, and I'm constantly surprised to see how some companies enter this treacherous territory totally unprepared. I don't expect Vivus to fall into that category tomorrow.

I was emailed some commentary from a biotech stock newsletter that's short Vivus. The newsletter said, in part, that the FDA's relatively benign review of Qnexa posted online Tuesday was a bad sign because it gave the agency free reign to carpet bomb the drug with criticism at Thursday's panel.

I disagree. I find that the FDA is never shy about voicing a negative opinion in briefing documents when the agency doesn't like something. What surprised me most about the FDA's Qnexa review was the lack of a smoking gun. I kept waiting for that devastating analysis or piece of negative data that we didn't know about. For the most part, nothing of the sort was in the FDA's review. That's why Vivus shares have been up for the past two days.

I don't anticipate much debate about Qnexa's efficacy. The pill helps obese patients lose weight. Most of the contentious discussion will be about the drug's safety. I'm probably most interested in hearing the discussion on pregnancy risk since this poses a potential problem if/when Qnexa is approved and marketed.

From the FDA's briefing documents, the agency seems very concerned about the number of women in the Qnexa trials who got pregnant despite a requirement that they be using birth control. The two individual components of Qnexa -- phentermine and topiramate -- both carry Category C pregnancy risks, which tells doctors to treat pregnant patients with the drugs if the benefits outweigh the risks.

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