Why it’s Important not to Exclude Gender and Sex when it comes to Clinical Research

6 mins read

Traditionally, clinical study has either excluded women or not taken account of the numbers or effects of medicines of women taking part. As clinical research procedures have become ever more complex, it is becoming more apparent that there are significant differences between the way men and women contract illnesses and respond to treatment.

While substantial progress has been made to rectify this oversight in recent years, government recognition of these biologically differences wasn’t officially recognised until 1993, when the National Institutes of Health mandated that women and minorities be included in clinical trials separately.

Recognition of the medical research gender gap

Research has shown that clinical studies have either had a very low number of women in the trials – as low as 33% in Europe – and has not always taken into account the differences between male and female reaction to the medicines being tested. Since many medications work differently between men and women, this is a very serious oversight on the part of clinical research bodies. Given the current understanding of medicine, not only should women be an equal number to men in many clinical trials, but the biological processes by which the medicine is absorbed and processed in the body should be assessed. This idea is only now being considered at a regulatory level.

Every cell – not just every body – has a sex

The sex of a person is marked throughevery cell of the human body. A woman isn’t a woman due to her genitalia – from the cells in her heart to those in her brain, she has a distinct biological make-up which differs from men in many ways.

The biological differences are often great enough that medicines work differently according to the sex of the patient. For example the US FDA has licensed the antidepressant medication sertraline for the treatment of Post-Traumatic Stress Disorder (PTSD) in females but not in males, because of the ways the medicine

operates in the brain. Serotonin – the neurochemical which reacts with the medicine in the brain, is absorbed differently in men and women. This means that sertraline is more effective on females in dealing with the symptoms of PTSD.

Another example lies within benzodiazepine sedatives. After taking these sedatives, temazepam is cleared out of male system far more quickly than the female’s as reactions to the medication is vastly different. These two medicines are absorbed in different ways and thereby the half-life of the medications differ according to the sex of the person taking it.

Diseases where sex matters

Heart disease is the biggest killer of women in Europe and the US, and Alzheimer’s disease hits more women than it does men – over 60% of Alzheimer’s disease sufferers are women. These two diseases are major focuses for sex related clinical research, and there has only been a recent push by clinical research organisations in either of these fields to understand how to treat women with these conditions.

Research into the role of menopause has been crucial to the development of clinical trials for these particular diseases. After menopause, the composition of cholesterol in women changes. LDL cholesterol particles, which at certain levels can be good for you, have been shown to be denser in postmenopausal women and thereby contribute to arterial hardening (atherosclerosis). However, in men, LDL cholesterol seems to maintain the same health benefits regardless of age.

At least two recent trials on cholesterol reducing drugs – important for heart disease – have overlooked the sex differences and have potentially missed an important market. If they were shown to be particularly better or worse for females, the medicines could have been better targeted at a specific sex and potentially more effective on female patients.

What of the future?

As the understanding that males and females differ at a cellular level reaches regulatory bodies around the world, a push is being made to differentiate the way research is done to account for patient’s differences. One concern on the part of pharmaceutical companies and research bodies is that this could seriously increase the amount of work required in order to license medicines, and this would increase the cost of medication for the consumer. However, the outcome may well be beneficial as males and females can receive better targeted treatments for their diseases and ailments. If the cost implications don’t outweigh the benefits, then this will surely be good for the goal of tackling the major health issues that face us all.

About the Contributor

This article was produced by Richmond Pharmacology, a clinical research organisation (CRO) based in London, UK specialising in clinical trials, TQT studies and early phase studies.

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