A New Medication for Weight Loss

By Craig Primack MD, FAAP Obesity Medicine Specialist Co-director, Scottsdale Weight Loss Center

Posted on | By Craig Primack MD, FAAP

Editor's Note: Qnexa has been renamed Qsymia and as of September 18, 2012 is available in pharmacies.  

Qnexa is a new, potent, effective and safe weight-loss drug that will help in the fight against obesity; it is poised to become the first FDA-approved weight-loss pill in 13 years. Qnexa is a combination pill of two medicines already on the market: phentermine and extended-release topiramate. Both drugs have been shown to help weight loss when used as part of a comprehensive weight-loss program led by a medical obesity specialist physician and together seem to be synergistic, not just additive.

Why are medical obesity specialists so excited for Qnexa?

The last time a new weight-loss drug was approved was in 1999. In these 13 years, the numbers of the overweight and obese have increased significantly. It is now estimated that 2 of every 3 people are overweight, and about 30% of the population is obese. The studies that looked at Qnexa showed 9.8-14.7% weight loss, depending on the dose and the amount that you are overweight. A 10% weight loss is enough to improve many weight-related diseases such as pre-diabetes, high blood pressure, high cholesterol and sleep apnea. 

I have been prescribing this combination of drugs since first hearing about the Qnexa studies back in 2009. At the time, we were using both phentermine and topiramate for weight-loss – but individually. Their side effects are quite different so that some patients did better on one drug and some did better on the other. 

If there was a reason to be put on one or the other drug, we did so. For example, if a patient had migraines, we chose topiramate. If they were free of heart disease, we chose phentermine. Now, as my experience with the combination has grown, we commonly start with one drug, more often it is phentermine. For some, the phentermine’s effect is incomplete and adding topiramate has really helped.

Like all drug therapies, patients respond differently to the same drug. For a small few, their hunger is so little that we have to decrease the dose so that they actually eat regularly. For most, adding the second drug boosts the appetite-suppressant effect and there is less hunger. In a small percentage, the second drug does not seem to add much or the side effects are too much, and we go back to a single drug therapy. In my practice, I always use medications in combination with dietary change, exercise, a behavior-based class series, accountability, and adequate sleep counseling.  

Article written by Craig Primack MD, FAAP
Obesity Medicine SpecialistCo-director, Scottsdale Weight Loss Center