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# FDA_to_Review_Weight_Loss_Drugs
- URL: https://www.foodconsumer.org/fda_to_review_weight_loss_drugs_071220101025/
- Published: 2010-07-12T11:22:00.000Z
- Updated: 2026-09-20T15:49:41.000Z
- Description: The FDA starts reviewing Qnexa, with lorcaserin due in September and Contrave in December. Qnexa, a phentermine-topiramate combination, cut body weight 13 to 15% in trials but had the highest dropout rate over memory and concentration problems. Lorcaserin had fewest side effects and least effect.
- Author: Rachel Stockton
- Tags: Obesity, Avoiding Illness, #vivvo-import

Beginning Monday, the FDA will begin reviewing data on three new weight loss drugs seeking approval from the agency.

The first one to be analyzed is Qnexa, which is manufactured by Vivus. Arena Pharmaceuticals’ lorcaserin will be looked at in September, followed by Contrave (Orexigen Therapeutics, Inc) in December.

When it comes to weight loss drugs, there really isn’t much new under the sun. Qnexa is a combination of phentermine, an amphetamine, and topiramate, which is an anti-convulsant. While phentermine reduces appetite, the topiramate makes a person feel more satiated. Pharmaceutical experts believe that by targeting more than one pathway in the brain, combination drugs such as Qnexa are more likely to be successful.

And, in clinical trials, Qnexa has performed better than the other two drugs. In order to be deemed effective, a weight loss drug must reduce body weight by at least 5%; Qnexa has been found to reduce it by 13-15%.  
  
However, as with many weight loss drugs in the past, there are some unpleasant side effects. Of the trio of new drugs, Qnexa had the highest dropout rate because of memory and concentration problems. Arena’s drug, lorcaserin, had the least number of side effects, but was also the least effective; trial participants only lost 5% of body weight.

Historically, obesity drugs haven’t particularly fared well; the most notorious of the genre was fen-phen, which was pulled from the market in 1997.

Fen-Phen was a combination of phentermine, which makes up half of Qnexa, and fenfluramine. Although effective at reducing weight, a study by the New England Journal of Medicine found a 23-fold increase in the risk of pulmonary hypertension in patients taking fen-phen. The drug was also linked to a rare valvular disease, according to the Mayo Clinic.  
Wyeth, the manufacturer of fen-phen, faced billions of dollars in legal damages following the allegations.

More recently, the drug alli, an over-the-counter formulation of the prescription Xenical, has also come under fire. In 2009, the FDA required a revised label for the drugs, warning consumers of rare cases of liver injury associated with the drug.