There is no obligation to test drugs on individuals who are obese, which presents a significant issue.

Over 40% of adults in America are classified as obese, but the effectiveness of their medications is often not evaluated in individuals with larger body sizes.

This is due to the fact that they are not obligated to be incorporated in pharmaceutical research. Additionally, they are frequently deliberately excluded.

According to Christina Chow, a researcher in the field of drug development, clinical trials and dosage guidelines do not always guarantee the safety and effectiveness of drugs for individuals with obesity. She has highlighted the difficulties in addressing obesity in drug development and notes that there is insufficient focus on studying its impact.

Many widely prescribed drugs and over-the-counter medications work differently in people who are obese, but exactly how and at what dose often isn’t clear. Research suggests that may include antibiotics and antifungal drugs used to treat serious infections, synthetic hormones used in Plan B emergency contraception and even ibuprofen, the common painkiller sold as Advil.

The U.S. Food and Drug Administration and the National Institutes of Health, which oversee and finance drug testing, are placing increased emphasis on addressing the deficiencies in research. During a workshop in the previous year, FDA Commissioner Dr. Robert Califf recognized a “lack of evidence” regarding the effects of medications on obese patients. A representative for the NIH stated that they now urge researchers to take into account the potential consequences of excluding obese individuals from their studies.

During a recent medical convention, Chow gave a summary of over 200 research studies for new medications in the United States from the previous year. However, she noted that approximately two-thirds of these studies did not address weight or body mass index, which is a standard measure of obesity. This lack of consideration could potentially exclude individuals with obesity from participating in the studies, according to Chow.

According to Chow, who is employed at Emerald Lake Safety, a company in California that investigates severe drug reactions, the majority of studies that mentioned weight used it as a criterion for excluding individuals with obesity from participating. A BMI (body mass index) of 30 or above is considered indicative of obesity.

In the past, some groups were not included in testing due to concerns about potential harm, such as pregnant individuals and children. Women, people of different races and ethnicities, and older adults have also been underrepresented, but recent efforts have aimed to increase diversity.

Dr. Caroline Apovian, a researcher at Brigham and Women’s Hospital in Boston and co-author of Chow’s study, stated that the justifications for excluding individuals with obesity have been in place for a long time and are diverse.

According to her, individuals who volunteer for research studies are typically thinner and do not represent the overall population. Researchers also have concerns that obesity-related health issues may affect their findings.

She stated that patients with obesity often have a higher number of comorbidities compared to others. This includes a higher prevalence of diabetes, heart disease, and strokes.

Experts have warned that if medications are not researched in a condition that impacts 42% of the American population, the potential consequences can be severe.

According to Apovian, certain medications may accumulate in fatty tissues instead of the bloodstream. This can result in lower levels of medication in the blood, leading to inadequate treatment.

In individuals who are obese, certain medications may have a longer duration of action. This could lead to potentially dangerous interactions if another medication is introduced too soon.

Rexulti, an antipsychotic medication, is commonly recommended for individuals with schizophrenia or major depressive disorder, according to Chow. Studies have indicated that in individuals who are obese, it may take a longer period of time to achieve the necessary level of Rexulti for it to be effective. As a result, patients and their physicians may prematurely discontinue treatment or assume that the medication is ineffective.

Chow emphasized the importance of treating schizophrenia properly, as failing to do so or not providing enough treatment can pose a danger to both the individual and those in their vicinity.

Dr. Alison Edelman, a researcher and OB-GYN at Oregon Health & Science University, has conducted studies on contraception and obesity. According to her findings, the emergency contraception drug Plan B One-Step may not be as effective in individuals with obesity due to the active drug, levonorgestrel. This can potentially result in drug failure and unintended pregnancy. However, the FDA has stated that the available data is insufficient and conflicting, therefore they have not mandated a label warning.

Research indicates that even a widely used drug like ibuprofen, also known as Advil, may not effectively alleviate pain in individuals with higher body weights when used according to the recommended instructions.

Dr. Colleen Tenan, a member of the Association of Clinical Research Professionals, stated that doctors would not be able to properly adjust dosing for obesity without sufficient testing and explicit directions.

“It can be challenging to be a doctor and deviate from the usual prescription range,” she stated.

According to Edelman, there is change on the horizon, but it is happening at a slow pace. In 2019, the FDA released preliminary instructions regarding hormonal birth control, requesting that research sponsors remove limitations based on body mass index and include women who are obese. Despite the fact that these instructions are not yet finalized, they have already influenced the way she and other researchers conduct their studies.

“It is crucial that we continue to make progress in this area,” she stated. “Without proper representation in our study population, treatments may not be as effective for all individuals.”

Meanwhile, Apovian suggested that patients inquire with their doctors about whether the recommended dosage of a medication is suitable for their weight. While the doctors may not have the answer, this could initiate a crucial discussion about the most effective treatment.

She expressed that this is a significant problem and emphasized the importance of patients voicing their concerns.


The Howard Hughes Medical Institute’s Science and Educational Media Group provides support to The Associated Press Health and Science Department. The AP is solely responsible for all of its content.