Issue: February 2012
February 01, 2012
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Phentermine/topiramate improved weight loss when added to lifestyle modifications

Garvey WT. Am J Clin Nutr. 2011;doi:10.3945/ajcn.111.024927.

Issue: February 2012
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Controlled-release phentermine/topiramate combined with lifestyle modifications appears to be an effective option for sustained treatment of obesity complicated by cardiometabolic disease, according to researchers from the University of Alabama at Birmingham.

“Controlled-release phentermine/topiramate was also associated with sustained improvements in the clinical manifestations of weight-related cardiometabolic disease, including hyperglycemia, dyslipidemia and elevated BP, despite reduced use of concomitant medications,” the researchers wrote.

The researchers conducted a placebo-controlled, double blind, 52-week extension study in which volunteers continued with the original randomly assigned treatment to complete a total of 108 weeks. The groups received placebo, 7.5 mg phentermine/46 mg controlled-release topiramate or 15 mg phentermine/92 mg controlled-release topiramate. All of the volunteers participated in a lifestyle modification program.

The extension study included 676 participants, and 84% of them completed the study. At week 108, controlled-release phentermine/topiramate was associated with a significant sustained weight loss compared with placebo (P<.0001). For placebo, the mean percentage of body weight change from baseline was –1.8%, vs. –9.3% for the 7.5-mg/phentermine/46-mg topiramate group and –10.5% in the 15-mg phentermine/92-mg topiramate group.

Significantly more participants treated with controlled-release phentermine/topiramate achieved weight loss of at least 5%, 10%, 15% and 20% vs. placebo. Controlled-release phentermine/topiramate also improved CV and metabolic variables, and decreased rates of diabetes compared with placebo. Controlled-release phentermine/topiramate was well tolerated and associated with reduced adverse event rates between weeks 56 and 108 compared with weeks 0 to 56.

“The unmet clinical need for effective weight-loss medications, together with the favorable risk–benefit profile in the current study, suggests that controlled-release phentermine/topiramate in conjunction with a lifestyle-intervention program could be a valuable therapeutic approach to counteract increasing rates of obesity and its related complications,” the researchers wrote.

Disclosure: Vivus Inc. provided funding and essential materials for this study.

PERSPECTIVE

Steven R. Smith, MD
Steven R. Smith

There are a couple of important things about this study. First, we’re all concerned about not just weight loss, but how long they can keep weight off. This is one of the few long-term studies of obesity drugs that has been able to demonstrate long-term efficacy. That’s critically important because our patients are pretty good at losing weight on their own, but they’re not very good at keeping the weight off. The ability to show durability of weight loss is clinically important because it gives us an additional reason to believe that obesity drugs are going to work in the practice. The other thing that is important is that they were able to keep the volunteers in the study with high participation rates. There has always been a critique of weight-loss studies that too many people drop out or people don’t like to take medications if they don’t work. The number of people they were able to keep in the study gives us confidence in the results. The take-home message is that with this specific combination, the weight loss was really good, and it was sustained. What this suggests is: If they can clear the regulatory hurdles, physicians who prescribe this combination in the clinic are going to have long-term weight-loss results.

Steven R. Smith, MD
Executive Director, Florida Hospital-Burnham Clinical Research Institute

Disclosure: Dr. Smith is a consultant for Amylin, Arena, AstraZeneca, Excelixis, Five Prime, Lilly, Novo Nordisk, Orexigen, Takeda, Third Rock, Wyeth and Zafgen. He is on the advisory board of Amylin, BMS, Lilly, Orexigen and Takeda. He receives research support from Novartis, Orexigen and Takeda.

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