Shares of drug developer GlaxoSmithKline (NYSE:GSK) fell an additional 5% last week and hit new 52-week lows on Friday after the Food and Drug Administration released briefing documents concerning the cardiovascular risks of its lead diabetes treatment Avandia.

Ever since the results of a meta-analysis covering numerous Avandia studies was published in the New England Journal of Medicine earlier in the year, Glaxo has been under fire for the possible increased risk of cardiac ischemic events (a heart attack, for example) that may occur with diabetics taking Avandia to control their blood glucose levels.

To come to some conclusions and recommendations about what to do following the publication of the NEJM article as well as a result of new data submitted by GSK, the FDA decided to move up an already planned advisory panel to discuss Avandia and the other compounds in its class of anti-diabetic compounds called thiazolidinediones. On Friday the FDA released its 436-page document discussing these compounds (seen here; link opens PDF).

After personally reviewing the FDA and Glaxo briefing documents, a vote to take Avandia off the market does not seem likely. While the drug had a higher incidence of cardiovascular adverse events (some already previously well known) in some of the 42 studies reviewed by the FDA and Glaxo, it does provide many benefits to type 2 diabetics as well. Also, some of the studies testing Avandia against other anti-diabetic compounds showed the incidence of serious cardiovascular events to be lower for patients taking Avandia versus the other therapies. Considering that type 2 diabetics generally have to be on some sort of treatment as their disease progresses, this is a very important point that Glaxo will surely drive home during the advisory panel meeting.

Based on the data presented, the highly likely result of the advisory panel meeting today will be a recommendation to further tighten the Avandia label with more "black box" warnings and contraindicate its use with more compounds like insulin injections or for patients at higher risk of certain heart conditions.

It's worth mentioning that the FDA doesn't always follow the recommendations of its advisory panels but they serve as a good indicator of the regulatory actions the agency will take on a drug.

Considering the need that type 2 diabetics have for various classes of anti-diabetic compounds and the fact that Avandia is best in class on some efficacy and safety measures, the drug will still have some prescription demand even if the label is tightened and certain patient groups excluded from using it. This is definitely not the most desired outcome for Glaxo but at least it will retain some degree of sales with the drug.

Read more about Glaxo in these Foolish articles:

GlaxoSmithKline is a recommendation in our Motley Fool Income Investor newsletter service, thanks to its 3.9% dividend yield. Find out what other companies are featured by taking a free 30-day trial today.

 Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.