Are you an optimist? "In the [complete response letter], no new clinical studies were requested."

Or a pessimist? "However, in the event that any of the [Food and Drug Administration] concerns are not alleviated, additional clinical studies may be required."

There was something for bulls and bears alike to love about the FDA turning down VIVUS' (Nasdaq: VVUS) obesity drug Qnexa yesterday. Or put another way, there's no easy way to know VIVUS' chances for getting an approval on the second try.

Qnexa is a combination of phentermine -- the phen in fen-phen -- and the active ingredient in Johnson & Johnson's (NYSE: JNJ) migraine and epilepsy drug, Topamax. The latter is known to cause birth defects if taken by pregnant women, and the FDA wants further information to ensure that VIVUS has a handle on the potential for Qnexa to cause birth defects and has a plan for avoid the risk in women of childbearing age.

The bigger issue could be the FDA's request to determine whether the elevated heart rate seen in patients taking Qnexa translates into an increased risk for major adverse cardiovascular events such as heart attacks and strokes. The company does have two-year safety data to share with the FDA, but whether that'll be enough to satisfy the request remains to be seen. Proving that a drug doesn't cause heart problems can require a large trial. Check out the size of the phase 3 trials for GlaxoSmithKline's (NYSE: GSK) darapladib and Merck's (NYSE: MRK) vorapaxar, for instance.

VIVUS seems to think the FDA's request is fairly minor. The drugmaker plans to respond to the FDA in about six weeks. Compare that to Arena Pharmaceuticals (Nasdaq: ARNA), which got a complete response letter last week but needs to do some animal testing and complete the report on yet-to-be-released data from a clinical trial at the very minimum. A resubmission by the end of the year is all but impossible for Arena.

Where does the pair of rejections leave Orexigen Therapeutics (Nasdaq: OREX), which will go in front of an advisory panel in December and receive a decision at the end of January? In theory, the delays mean Contrave could be the first obesity drug to market. But I have to guess that the FDA will make Orexigen jump through hoops just like the first two.

Investors in VIVUS can only hope that those hoops aren't too numerous.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.