Why Are Obesity Medications So Few?

At the Endocrine Society meeting in San Francisco which I am thrilled to be attending, I began today by listening to Dr Caroline Apovian of the Boston Medical Centre describe the background behind why there are so few medications available to treat obesity.

Worldwide, there are only a few meds available to treat obesity – contrast this with the several dozens of medications available to treat high blood pressure or type 2 diabetes.

The first issue Dr Apovian talked us through is the history of medications previously used to treat obesity, which were subsequently withdrawn from the global market due to safety concerns. ‘Fen-Phen’, a combination of fenfluramine and phentermine, was withdrawn in 1997 as it was found to cause valvular heart disease (attributed to the fenfluramine component); rimonabant was withdrawn due to concerns regarding potential psychiatric side effects and suicide risk; sibutramine was withdrawn in 2010 due to concerns that it may increase the risk of cardiac events in high risk patients. This track record made the FDA reluctant to approve any new medications for obesity for a full 13 years until two new medications were ultimately approved by the FDA in 2012 (you can read about these approvals here, and here).

Another reason why the FDA is extremely hesitant to approve obesity medications is because of the large number of people that could potentially be exposed to these medications, with 33% of American adults currently meeting the BMI criteria for obesity (you can calculate your own Body Mass Index in the right hand column here). For example, the recently FDA-approved medication for obesity called Qsymia, which is a combination of the migraine and antiseizure medication topiramate (Topamax), and the stimulant phentermine, was originally rejected by the FDA, despite both medications being available for years individually. One of the reasons why the FDA rejected this combination initially was due to the fact that topiramate can cause birth defects. Given that this drug has long been used for years in reproductive aged women for migraines or epilepsy, it would seem that the same precautions would apply (eg to ensure adequate contraception is used). Presumably, the FDA was worried about the sheer numbers of women that would be exposed to topiramate as an obesity treatment with the concomitant risk of birth defects. They ultimately did approve the combination therapy for obesity, in 2012. (There are other safety concerns as well, which you can read about here).

A final reason that needs important emphasis, is that there is still sadly a strong stigma around obesity, in general society but also sadly within the medical community. For example, it is only recently that obesity was even formally recognized as a chronic disease by the medical community.

Put all of these issues together, and the context becomes one of extreme difficulty in gaining approval for new obesity treatments. Clearly, safety is paramount and always the #1 concern, but each medication should surely be evaluated on its own merits, and not on the basis of fear generated by other medications that failed in the past. On an individual level, side effects should be considered equally important, regardless of whether 100 people or 100,000 people are candidates for treatment. Finally, there is no place for a stigma of any kind against any medical condition, and stigma must not stand in the way of moving forward in developing new ways to treat the chronic medical condition of obesity.