The Globe and Mail continues to provide me with interesting articles. The latest article (Drug makers ignoring key gender differences, immunologist warns) is about the role that gender plays in the drug development process.

The article talks about how immune-system cells respond to infections and states …

“…the profile of that immune response is different in men and women…”

It further highlights the types of diseases that each gender is more susceptible to.

“In general, men are more susceptible to viruses and bacteria and tend to develop more severe infections. Women, however, are more likely to develop autoimmune diseases like rheumatoid arthritis or lupus.”

The role that menstruation plays in the process of immune response and how both menstruation and oral contraceptives can impact how a woman’s immune-system responds to infection and treatment was of particular interest.

“The stage a woman is at in her menstrual cycle can influence how her body responds to invading bacteria, viruses and parasites, such as the one that causes malaria.

It is complicated, because estrogen levels affect different types of immune-system cells in different ways. Oral contraceptives may also have an impact.”

I had a hard time imagining that this was news to anyone involved in the medical field but the article goes on to state …

“… pharmaceutical companies don’t enroll enough women in clinical trials to get an adequate assessment of how this [the stage a woman is at in her menstrual cycle] might affect how well a drug works for women compared to men…”

That piqued my curiosity so I did a little research. The EMEA (European Medicines Agency) has a paper discussing “gender considerations in the conduct of clinical trials” (link opens a PDF file).

“An underlying principle of drug development is that “patients entering clinical trials should be reasonably representative of the population that will be later treated by the drug” as subpopulations may respond differently to a given drug treatment.”

Further information was found on the website for Health Canada in their Therapeutic Products Programme Guidelines. The guideline for Inclusion of Women in Clinical Trials, which dates back to 1997, states that

“It is important to ensure that women are enrolled in clinical trials at all stages of drug development in order to define the risks and benefits associated with drug therapy in this segment of the population. Since physiological changes and hormonal levels during child-bearing years and menopause, as well as the use of oral contraceptives or hormone replacement therapy, may affect the efficacy and safety of a drug, the influence of these parameters should be studied during drug development.”

That seemed fairly straight forward to me but there must be a reason why women are under-represented in clinical trials. I wondered if it had to do with psychological differences, that perhaps men were less concerned about the potential risks involved with participating in a clinical trial. An abstract on the ASCO (American Society of Clinical Oncology) website regarding the ‘Psychological characteristics of patients who enter clinical trials’ indicates that this isn’t true.

“Age, race, gender, marital status, and disease or symptom severity do not affect participation in clinical trials.”

Admittedly these results are for Oncology trials, so perhaps they are skewed because of the seriousness of the disease. Unfortunately it still begs the question as to why not enough women are enrolled in clinical trials. The only reason that I could find relates to reproduction and the unknown teratogenic impact of new drugs, which as any parent knows is reason enough.

Regardless of why women are not fully represented in clinical trials, I found it interesting to see how this supports the concept behind The Gender Divide. It is hard to imagine a modern world where women live longer then men and some people may consider that to be improbable. However it is clear that despite all the advances in medicine, we still don’t fully know how various drugs impact the human body and the role of gender on that impact.