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An FDA panel's decision to reject the diet drug Qnexa has had a disastrous effect on manufacturer Vivus' stock. Analysts say it might be a bad omen for two other diet drugs expected to be recommended for FDA approval later this year. 

A major factor in the panel’s decision to reject Qnexa seems to be the lack of data about the drug’s long-term effects.

“What really seemed to tip the balance of the debate were concerns about the possible adverse impact of this drug on pregnant women. ... A drug of this type would be so popular that you have to err on the side of mitigating risk before it ever goes to market.” (CNBC)

NPR suggests that the panel might have been especially cautious because of controversy surrounding the possible risks of taking diabetes drug Avandia and previous problems caused by weight-loss medication.

“The panel members may have felt it was time to get tough on a drug with baggage. Past problems when millions of people took diet drugs that harmed them — notably the drug cocktail known as fen-phen — also hung over the deliberations.”

Another thing about Qnexa that worries medical professionals is the fact that it’s a combination of drugs — one that hasn’t been studied in-depth on humans yet. Dr. Marc Siegel shared his concerns on Fox News:

“My problem with this pill, Qnexa, is the combo part. I’m not a believer in those pills in general. I don’t know which is doing what. ... What happens if one of my patients has a side effect? I won’t know which active ingredient is causing it.”

But, like Qnexa, they are both combinations of existing medications. Dr. Jennifer Ashton explains the make up of the drugs on CBS News:

“One drug is called Contrave, and it’s actually a combination of an addiction drug and an anti-depressant. It’s thought to work in the brain and suppresses appetite. With the other drug, called Lorcaserin, patients lost on average about 5 percent of their body weight, and common side effects included headache and nausea, but regulators will be also looking for heart problems.”

The other two diet drugs poised to seek FDA approval this year have not caused the same negative side effects in trials.  Stocks for the drugs have been unpredictable since Qnexa’s rejection. Businessweek reports:

“Vivus Inc. shares plunged the most ever in New York trading the day after U.S. reviewers recommended against approval ... a decision that analysts say may threaten makers of competing drugs.”

But as ABC points out, whatever the fate of these drugs, their money-making potential is enormous.

“We do know that diet pills are big business, and if these pills are approved, industry watchers believe the marked could swell to more than $10 billion in coming years.”

So, what do you think? Are weight loss drugs worth the risk? Or are manufacturers trying to cash in on America’s obesity problem?

WRITER: JESSICA STEPHENS