Scientists from the National Institutes of Health (NIH) have called on drug researchers to immediately start including female test subjects in drug research trials.
Many animal trials — especially those conducted by drug and medical device makers — include only male rats, pigs, or dogs. In a paper published last week in the journal Nature, Dr. Francis Collins, director of the NIH, and Dr. Janine A. Clayton, director of the Office of Research on Women’s Health, decry the “over-reliance on male animals and cells in preclinical research.” This “obscures key sex differences that could guide clinical studies,” Slate reports, and “women experience higher rates of adverse drug reactions than men do,” Collins and Clayton write.
Biological differences between male and female bodies mean that illnesses can manifest differently in men and women and women may respond differently to treatment. Researchers have avoided using female animals for fear that female reproductive cycles and hormone fluctuations would “confound the results of delicately calibrated experiments, the New York Times explains. But the absence of female subjects means researchers don’t know how the drugs will work on women. And medical devices like replacement joints may not properly fit women’s bodies, leaving women with poorer results.
The Food and Drug Administration (FDA) has lowered the recommended dose for the sleep medications Ambien and Lunesta because studies have shown that women metabolize the active ingredient in each more slowly than men do. This leaves women at risk for drowsiness and impairment the next morning, which can prove dangerous for driving. For statin drugs, widely prescribed to lower cholesterol, testing was done mostly in men, thus providing limited evidence of their benefit to women. This situation is true for many drugs and treatments. Even when researchers study diseases such as anxiety, depression, thyroid disease, and multiple sclerosis, which are more prevalent in women, they often rely on male animals in testing, says Dr. Irving Zucker of the University of California, Berkeley, who has written extensively on gender bias in scientific research, according to the Times.