There hasn't been much to update with Arena Pharmaceuticals since the Food and Drug Administration's approval of Belviq. The biotech remains in limbo waiting for the Drug Enforcement Agency to sign off on the scheduling of the obesity drug. I continue to expect the DEA to issue a no-big-deal Schedule IV designation near the end of the year, which would allow Arena to launch in the first quarter of 2013.

Arena's most direct competitor, VIVUS, has made news lately, however. The biotech launched Qsymia in September. Thus far, prescription data has been modest, but early sales are unlikely to predict the long-term success of either Qsymia or Belviq. We won't get a full quarter of sales data until VIVUS releases fourth-quarter results early next year.

Getting in on the market second, a few months behind Qsymia, will likely have little effect on Belviq's sales. It's not enough time for VIVUS to dominate the market; doctors will still be in wait-and-see mode, trying the drug out on a few patients. And if they're trying out Qsymia, it seems reasonable that they'll give Belviq a shot, too.

VIVUS got some bad news in Europe, where regulators refused to approve Qsymia. For Arena, this is either really good news – less competition – or really bad news because European regulators are going to be harder to satisfy than the FDA was.

I tend to be in the former camp. One of the reasons cited for the rejection was because regulators were concerned that Qsymia would be used by patients for whom it's not indicated. One of the components of Qsymia is linked to birth defects, so it shouldn't be taken by pregnant women. It also has other side effects that make in inappropriate for casual weight loss.

In the U.S., the FDA was able to manage the risk by establishing a Risk Evaluation and Mitigation System to track doctors that prescribe the drug and ensure they understand the risk. The European Medicines Agency doesn't have a system that affords it that kind of control over a product once it's on the market. Since Belviq's side effects are tamer than Qsymia's, hopefully it won't run into the same problems.

A decision on Belviq's EU application is expected in the first half of next year (the timing isn't certain because the clock stops each time the company has to gather information to answer regulators' questions). We may get an update on the third quarter conference call scheduled for November 5.

At the time of publication, Brian Orelli owned no shares of the companies mentioned. The Motley Fool owns shares of Abbott Laboratories.