As most of us who have taken the antiseizure medication Topamax for migraine prevention already know, it can take a knock out punch to your appetite. As researchers have recognized this they’ve started testing it as a weight loss medication.
An investigational weight loss pill called Qnexa combines the medications Topamax and Phentermine. Phentermine is one of the most widely-used medications for weight loss in the United States. An investigational trial has shown an average weight loss of 22 pounds in one year for patients taking Qnexa and lower blood pressure, cholesterol and blood glucose levels. Compared to patients assigned to diet and exercise counseling alone, patients taking Qnexa experienced significantly greater weight loss. However, we already know Topamax alone carries with it some serious side effects.
Topamax has been associated with extreme nausea (likely the reason so many people lose weight on it), heart problems, cloudy thinking, lethargy and an increased risk of birth defects in babies born to women taking it. Infants born to women taking Topamax have been found to have an increased risk of cleft lip or palate. In fact, the Food and Drug Administration (FDA) recently rejected Qnexa’s application for approval as a weight loss medication because of these risks, particularly the heart risks and birth defects. While weight loss is undoubtedly a serious medical issue, the FDA did not believe the benefits of Qnexa outweighed the significant risks for the target population. However, researchers said there were no birth defects among the 34 babies born to women taking Qnexa in this trial and that based on these results they plan to reapply for FDA approval before the end of 2011.
Although the researchers said the weight loss results carried over into the second year for patients taking Qnexa, they acknowledged there is no way of knowing whether it is safe for patients to consume Qnexa for the long term or for a life time. They don’t believe the weight loss would necessarily sustain itself if the patients stop taking Qnexa. They also pointed out other weight loss drugs that have shown short term success did not turn out to be safe enough for long term use and that this will be the most important bar any potential weight loss drug has yet to overcome.