In the Fall issue of OAC’s Weight Matters Magazine, we shine a light on some troubling gaps in the FDA drug approval process and drug labeling that are hurting people with obesity. Currently, there are no FDA requirements to evaluate how prescription drugs perform in individuals with obesity. If this comes as a surprise to us, perhaps it shouldn’t be. The FDA has a history of permitting drug companies to test drugs on specific subsections of the U.S. population, rather than on every group that might use the drug. Drugs intended for use by all adults were routinely tested only on men until the 1990s, and drugs meant for use by children in addition to adults weren’t routinely tested on children until the early 2000s. Drug companies have an interest in testing on narrower subsections of the U.S. population because in these narrower groups, drugs are more likely to perform as expected, thereby increasing the odds of approval. Consequently, drug companies often structure clinical trials to exclude people with obesity.

Yet post-launch studies reveal that many drugs used by people with obesity are neither safe nor effective for this population. This holds true for various classes of drugs, including those for depression, schizophrenia, emergency birth control, heart failure, antibiotics, and antifungals. Essentially, any highly fat-soluble drug has a significant chance of behaving differently in the body of a person with obesity. However, without testing on people with obesity, there’s no way to determine whether the drug works well or at all in that population. Since the labels of these drugs often lack special instructions for people with obesity or any mention that the drug might be ineffective for this group, physicians have no way of knowing that the drug they’re prescribing may be unsafe or ineffective for their patients.

For instance, Rexulti is the brand name for a prescription drug owned by Otsuka Pharmaceuticals used to treat depression and schizophrenia, both serious conditions that can be life-threatening. Rexulti was not fully tested on individuals with obesity before its approval, despite the estimated nearly 60% obesity rate among people with schizophrenia, which is considerably higher than the 42% rate in the general U.S. adult population. A recent study revealed that Rexulti might take longer to reach effective levels in people with obesity or might never reach them. Ted Kyle, past chair of OAC, presented two abstracts at ObesityWeek, the preeminent international conference for obesity researchers and clinicians, providing new insights on this issue.

Posters Presented at ObesityWeek 2023

OAC has reached out to Otsuka to request they address this concern, and we intend to persist in contacting drug companies to ensure their labeling reflects safe and effective use for people with obesity. We have also urged the FDA to begin requiring testing of drugs that might behave differently in people with obesity before approval. Both Congress and the FDA have the authority to mandate testing for relevant audiences. For example, the FDA mandates certain drugs that might impact the liver or kidneys to be tested in people with liver or kidney disease. Far fewer people have liver or kidney disease than have obesity. People with obesity deserve to know that the drugs they use are safe and effective, and OAC will continue to advocate for that.

Click here to read the article in this issue of Weight Matters Magazine