A new study by University of Chicago and University of California, Berkeley researchers suggests that women are being widely overmedicated — and suffering excess side effects — because drug dosages are calculated based on studies done overwhelmingly on male subjects.
Scientists and medical professionals have long known that women experience more adverse side effects than men, even when drug dosages are adjusted for body weight. These side effects can range from headaches and nausea to bleeding and seizures. But for decades, women were excluded from drug trials due to the false belief that hormone cycles would skew test results.
Since 1993, the National Institutes of Health has mandated that trials should be run on both men and women. But there are thousands of drugs currently on the market that were approved before the 1993 ruling. In the current study, researchers found 86 drugs for which there was clear evidence of sex differences in how the body broke down the drug. For nearly all of these drugs, women metabolized them more slowly than men, leading to higher levels of exposure to the drug; in 96 percent of cases, this resulted in significantly higher rates of adverse side effects in women.
“There are a lot of drugs that are prescribed on a ‘one-size-fits-all’ basis, and it’s clear that this doesn’t always work,” said Brian Prendergast, a psychologist at the University of Chicago and a co-author of the study. “Especially for drugs that we already know have a wide therapeutic range — meaning there’s a wide range of doses that are still effective — we could do a lot better job of titrating dosages with sex in mind.”
The authors call for the FDA to post the gender breakdown of study participants in trial data for future analyses and to specifically label drugs that are already known to have sex differences. The information should also be discussed and included in medical education, the authors recommend.
The study, “Sex Differences in Pharmacokinetics Predict Adverse Drug Reactions in Women,” was published on the website of the journal Biology of Sex Differences. It may be accessed here.