Women are overmedicated and experience adverse drug pharmaceutical reactions almost twice as often as men because clinical trials are typically male-dominated, according to a new study.
Scientists at UC Berkeley and the University of Chicago found that sex bias in clinical trials means the US Food and Drugs Administration is often approving drugs—and determining correct dosages—based predominantly upon their observed effects on men, without taking into account the possibility that others might react differently to the substance.
According to the researchers, this goes some way toward explaining why people assigned female at birth have adverse reactions at almost double the rate of their male counterparts, and in more than 90 percent of cases experience worse side effects such as nausea, depression, cognitive deficits, seizures, and cardiac anomalies.
“Women historically were excluded from clinical pharmaceutical trials because of potential risks to individuals of childbearing potential,” the authors of the study write. “A consequence of this sex inequality hides in plain sight today: most drugs are prescribed to women and men at the same dose.”
The study, published last month in the journal Biology of Sex Differences, saw researchers trawling through more than 5,000 scientific studies of pharmacokinetics—that is, the branch of pharmacology that looks at how drugs are processed by an organism—to see whether a person’s sex had anything to do with the probability of them experiencing an adverse drug reaction. In an overwhelming majority of cases, it did.
Out of the 86 drugs evaluated, 76 were found to be processed differently by males and females—a variation that was not explained by body weight alone, the researchers note, and was most likely linked to pharmacokinetic differences.
This could have serious implications for cis women, trans men, and non-binary people assigned female at birth, who as a result of being underrepresented in trials are placed at an increased risk of experiencing adverse drug reactions.
Irving Zucker, lead study author and a professor emeritus of integrative biology at UC Berkeley, said in a statement that “when it comes to prescribing drugs, a one-size-fits-all approach, based on male-dominated clinical trials, is not working, and women are getting the short end of the stick.”
The researchers concluded that such an approach risks the overmedication of women and contributes to female-biased adverse drug reactions—and recommended that, in order to counteract the lack of representation in clinical trials, evidence-based dose reductions for people assigned female at birth need to be introduced for a range of drugs.
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