I am acutely aware of the obesity epidemic in this country. I’ve posted previously about how obesity may have surpassed smoking as the #1 preventabe cause of death in the U.S. Still the FDA approval today of Belviq, a sertonergic drug that brings back memories of Fen-Phen, Meridia and Redux (dexfenfluoramine) over concerns with their association with valvular heart disease, pulmonary hypertension and other concerns. The studies to date have been necessarily relatively short term, and the FDA is requiring Arena Pharmaceuticals to do continued aftermarket surveillance for these concerns.
My dilemma as a physician is how to balance the potential benefit of moderate weight loss vs. the potential for side effects from Belviq. Belviq appears to have some patients who respond well to treatment, while others respond less well. The anticipated weight loss is more than 5% of body weight over the initial 12 weeks o f therapy, with further weight loss expected in patients who continue therapy. Some patients will not respond with the anticipated 5% or more weight loss in the initial 12 weeks of therapy and in those patients it is recommended that the Belviq be discontinued. Obesity is a well-known risk factor for diabetes, degenerative joint disease, and other cardiovascular problems, so it is far from a benign condition. Belviq is a brand new drug, at least superficially similar to prior drugs that were found to have unexpected serious problems with sustained use, and I would argue that its risks are to some degree TBD (to be determined). The issue in its simplest terms is whether a drug like Belviq which offers a hope for modest weight loss is worth taking when the risks are still ill-defined. The answer is going to depend on the benefits side of the equation as much as on the risks side. Patient with morbid obesity may be willing and even appropriate candidates for taking more risk for a hope of weight loss because the potential benefits are larger. Patients with more moderate obesity, in the BMI >30 range for which Belviq has the FDA indication (BMI >27 with other risk factors) may be less likely to get major health benefits, and so the risk-benefit analysis may swing more towards not using the drug as the risks are likely to be just as high for them as in higher risk patients.
My approach for now is going to be to wait a bit to see how the early after-market reports of efficacy and side effects turn out, and if they seem OK to cautiously consider Belviq in carefully selected patients. An individual’s health risks from obesity are related to much more than their BMI. Do they also have diabetes, hypertension, congestive heart failure or osteoarthritic hips or knees? I expect to have patients requesting Belviq soon. I’ve already had patients asking for the generic components of the still-under-review Qnexa (phenermine plus topiramate). I hope that Belviq turns out to be even more safe and effective than the early studies suggest, but I will not be surprised if Belviq turns out to be less effective than early studies suggest and if some so far unfounded fears of cardiovascular side effect risks are realized.
Addendum: Since the publication of this post, and the subsequent reposting on the KevinMD blog the correctness of the information written in this article has been challenged in comments on that blog. In fairness when challenged by the writers of these comments I asked them to have them reposted here to present a balanced discussion. The crux of the disagreement lies in the specificity of the receptor where Belviq has its function. Belviq appears to be much more specific to the receptors that affect hunger than those in cardiac tissue, which may allow Belviq reduce hunger, lead to weight loss and avoid the cardiac side effects of earlier drugs that less specifically stimulated this receptor. See the comments below for more specific details. In addition I have changed the verbiage of the post to more accurately reflect the expected weight loss from Belviq.