03/21/2012 11:07 am ET Updated May 21, 2012

Qnexa: A Magic Bullet for Weight Loss?

For the first time in 13 years, another weight loss medication is coming to market with the promise to work like a magic bullet for obesity. Sound familiar?

In late February, an advisory panel to the Food and Drug Administration (FDA) voted 20 to 2 to recommend that Qnexa be approved for weight loss, which will likely happen in April. Qnexa is expected to facilitate a 10 percent reduction in body weight based upon clinical trials. It's already being predicted that annual sales of the drug could reach $1 billion to $3 billion.

Qnexa is a combination of two appetite-suppressing medications: phentermine and topiramate. Phentermine was previously combined with fenfluramine in the weight loss medication "Fen-Phen," which the FDA removed from the market in 1997 due to an increased risk of drug-induced fatal pulmonary hypertension and valvular heart disease.

Although fenfluramine was clearly the evil twin in that combination, phentermine is also riddled with potential adverse cardiovascular effects, including primary pulmonary, regurgitant cardiac valvular disease, palpitation, tachycardia, and elevated blood pressure. Topiramate was originally an anti-seizure medication that is also used to prevent migraine headaches. It has a number of adverse effects on the central nervous system, including forgetfulness, confusion, and incoherent speech. With risks like these, it should come as no surprise that in 2010, the same FDA advisory panel voted 10 to 6 to reject Qnexa.

So what's changed in just two years?

The drug's adverse effects that concerned the advisory committee in 2010 still remain and no additional safety data about Qnexa have been submitted to the FDA by its manufacturer, Vivus. Panelists did agree that Vivus should conduct additional studies to assess potential heart problems, recommending additional studies be conducted -- after approval.

I believe that the FDA panel probably reversed its opinion on Qnexa in part because of the current lack of medical treatments for obesity, which has reached epidemic levels. The only drug approved for the long-term treatment of obesity is Orlistat (Xenical), which blocks the absorption of fat but produces only a 5- to 7-pound weight loss, is riddled with unpleasant side effects (smelly stools, flatulence), and can potentially produce a whole host of nutritional deficiencies.

Qnexa might seem like a better option, but is it? We just don't know enough about its potential risks to say for sure whether this drug will be any safer than Fen-Phen or other pharmaceuticals.

A Better Way to Weight Loss

It's tempting to look for a quick fix for weight loss, but I believe that the best approach remains a sensible program of proper nutrition, exercise, and behavioral modification. We know that programs that combine this traditional approach to weight loss are successful, cost less than invasive procedures and pharmaceuticals, and are certainly less risky.

Unfortunately, many people are following the exact type of opposite lifestyle. We are becoming less physically active as a nation: In 1990, nearly 60 percent of the U.S. adult population reported little or no leisure-time physical activity. (1) By 2007, 78 percent of Americans weren't meeting basic activity level recommendations, while 25 percent were completely sedentary.

Another issue is our Standard American Diet, which promotes the over-consumption of poor-quality, calorie-rich fast foods that are addictive in taste and light on the wallet. Americans consume an average of less than one serving a day of whole grains, compared to nine servings of refined grains. Fresh vegetable consumption in the U.S. has declined by nine pounds per person over the past 10 years. Sweetener consumption is nearly triple dietary targets.

Americans are also eating more meals away than ever before, spending 47.5 percent percent of their food budget on meals outside of the home. Eating out can be convenient, but it's also caloric -- portions in restaurants just keep growing! Plus, foods eaten away from the home tend to be higher in fat. Just one additional meal away from home each week translates to roughly two extra pounds each year.

Our government also plays a role in obesity. The present farm bill legislation subsidizes farmers who grow corn, soy, and wheat, which provide raw material for highly processed, nutrient-empty foods. Unfortunately, subsidies make these less-healthy foods more economical, and therefore more attractive to many consumers. In the long run, however, these foods actually raise costs by promoting obesity. (2)

Obesity is a complex socioeconomic disease that is perpetuated by misguided food politics. They say it takes a village to raise a child -- and it takes a whole community to fight obesity, too. We can begin to stem the tide by passing legislation that makes whole foods affordable rather than subsidizing fast food commodities. We also need to encourage a slow but safe lifestyle transformation: Good nutrition, physical activity, mindful eating, and behavior modification should become first-line measures rather than risky quick fixes like pharmaceuticals. These medical interventions have become the proverbial finger in the dike and do not address the root cause of the obesity epidemic.

Desperate matters require drastic measures. Medical interventions have been lifesaving for many people and do have their place for those with severe obesity who have failed dietary and lifestyle interventions. That said, I still have many questions about the safety of Qnexa, regardless of its effectiveness. Do the potential risks outweigh the potential benefits? The jury is still out.

Yours in health and wellness,

Gerard E. Mullin, M.D.


(1) Siegel PZ BR, Frazier EL, et al. . Behavioral Risk Factor Surveillance, 1986-1990. MMWR 1991;1(40 (SS-4)):1-23.

(2) Putnam J AJ, Kantor LS. Food Review. In: Service USDAER, ed.; 2000:1-15.

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