Women Are More Vulnerable To Drug Side Effects Due To Lack of Testing: Study

According to the findings of new research, women are twice as likely to suffer from drug side effects, possibly because they are often under-represented in clinical trials and studies.

In a report published in the medical journal Biology of Sex Differences, researchers from the University of California, Berkeley and the University of Chicago indicate that women may be taking higher doses of some prescriptions drugs than needed, because the clinical trials that studied the drugs focused too heavily on male participants.

Researchers conducted searches of ISI Web of Science and PubMed databases conducted with combinations of the terms: drugs, sex or gender, pharmacokinetics, pharmacodynamics, drug safety, drug dose, and adverse drug reaction. The search yielded over 5,000 articles with considerable overlap.

The findings indicate there are significant sex differences for peak or maximum concentrations of drugs, as well as clearance and elimination rates.

Of the 86 drugs approved by the FDA and evaluated by the team, 76 had higher pharmacokinetics in women, meaning women were affected more than men. The drugs were processed differently by women. Overall, women experienced elevated blood concentrations and longer elimination times than men.

In more than 90% of cases women experienced serious side effects like headache, depression, nausea, drowsiness, cognitive deficits, seizures, excessive weight gain, hallucinations, agitation, and cardiac abnormalities, according to the findings. There was evidence indicating women experienced differences for 86 medications including antidepressants, cardiovascular drugs, anti-seizure drugs, painkillers, and others.

The findings indicate 96% of drugs had higher rates of side effects among women than men. The data indicates women may be largely overmedicated.

The role of sex as a biological factor in adverse drug reactions is poorly understood. Most drugs currently in use are approved based on clinical trials conducted on men.

For example, the sleep drug Ambien was dosed the same for men and women until 2013. The FDA had to recommend reducing the dosage for women by half after many users began experiencing next-morning drowsiness, substantial cognitive impairment, and increased traffic accidents.

This is based on a disregard of the biological differences between male and female bodies during research. Historically, women are excluded because researchers were concerned female hormone fluctuations would make women too difficult to study.

Furthermore, until the 1990s, women of childbearing age were kept out of clinical trials  because of liability concerns and exposing pregnant women to drugs that could harm a fetus. Newer studies include more women, but the studies often don’t analyze the biological sex differences.

To that end, women are given the same doses as men. The researchers concluded drug dosing should be reevaluated for women to account for higher blood concentrations and slower elimination rates that are not simply based on weight differences, but biological differences.

“The common practice of prescribing equal drug doses to women and men neglects sex differences in pharmacokinetics and dimorphisms in body weight, risks overmedication of women, and contributes to female-biased adverse drug reactions,” the study authors wrote. “We recommend evidence-based dose reductions for women to counteract this sex bias.”