Exposing Gender Differences in Adverse Drug Reaction Reporting

Gender differences continue to be a hot button issue across all industries, and drug safety is no exception.

In a new study published in the British Journal of Clinical Pharmacology, researchers from the Netherlands found 15 percent of adverse drug reactions disproportionately affected one sex out of 2,483 drug and adverse reaction combinations.

“Presumably the reason for these differences are both sex-related and gender-related factors,” said senior author Dr. E.P. van Puijenbroek, of the Netherlands Pharmacovigilance Centre Lareb, in the Netherlands. “These aspects need to be considered when evaluating the safety of drugs.”

Adverse drug reactions affect women about one-and-a-half times more than men. While not all adverse reactions are acutely serious, they can deter patients from adhering to their medication, which could deteriorate their health and decrease their quality of life. Even drowsiness – the result of taking a sedative or a seemingly innocuous side effect of some drugs – could have fatal consequences.

The researchers analyzed hundreds of doctor- and patient-submitted reports at the Netherlands Pharmacovigilance Center to identify gender differences among drug-adverse reaction combinations and among types of adverse reactions experienced. In 322 out of 363 combinations with a notable gender difference, women experienced more adverse drug reactions than men.

Thyroid drugs and antidepressants were the top drugs that led to the most adverse drug reactions experienced by women. Women most often reported headaches, dizziness, nausea and alopecia (hair loss) while men frequently reported aggression, tendon rupture and sexual dysfunction as adverse reactions.

The researchers speculate that these differences arise from a combination of biological differences (sex differences) and psychological, behavioral and/or cultural differences (gender differences). For example, women generally have lower body weight and different hormone compositions compared to men which could affect drug metabolism. As a result, they are prescribed lower doses of sedatives or anti-nausea drugs. As well, more women may consider hair loss as an adverse drug reaction compared to men and are therefore more likely to report it as such.

However, the researchers found that the same gender differences existed among adverse drug reaction reporting regardless of who submitted the report – the doctor or the patient. This suggests that adverse drug reaction reporting was unrelated to gender differences in reporting behavior or perceptions of these reactions. There are many other factors that could contribute to gender differences in adverse drug reaction reporting. A person’s age, as well as drug interactions from multiple prescriptions, could also affect the severity and frequency of adverse drug reactions.

There is a growing push to consider sex and gender differences in drug development and in the clinic. However, not all advances were made to bridge the gap. In 1977, the US Food and Drug Administration (FDA) released a guidance document suggesting women of childbearing potential should be excluded from early drug trials so as to protect the fetus. While the FDA had good intentions, all women were slowly phased out of all clinical trials – now, there is a paucity of female participants.

Studies like the Netherlands meta-analysis on adverse drug reactions highlight the need to better understand why gender differences exist and how they can be addressed in practice. More literature has emerged regarding sex and gender differences in cardiovascular disease, depression and blood transfusion success to name a few. Sex and gender differences are likely to play a greater role as personalized medicine advances.