Clients are asking... Is my medication safe for me? Breakthrough Fall 2004

At the Centre

"How do I know if the medication I'm taking is safe for women? Aren't most tests, or clinical trials, for safety and effectiveness performed on men?"

Wende Wood, CAMH Pharmacist, responds:

The appropriateness of how medications are tested for safety has certainly been a hot topic in the media recently. In the past, clinical trials, which are carefully conducted studies of new medications on human beings, were mostly performed on men. Today, however, current regulations require studies include testing the drugs on women as well. Also, clinical trials are only  one way to assess the safety and efficacy  of medications.

Clinical trials to test medications in humans before making the drugs available to the public only started to be required in the late 1930s. In 1964, international standards for ethical treatment in studies were set to protect "vulnerable subjects," including children, mentally disabled people, educationally disadvantaged persons, prisoners and pregnant women. Unfortunately many researchers extended the "pregnant women" exclusion to include all women of childbearing age, even those who claimed they would not or could not get pregnant.

The exclusion of women from drug tests became even stronger with the thalidomide and diethylstilbestrol tragedies in the 1960s, when pregnant women took medications that resulted in birth defects in their newborn children, and law suits from patients harmed by medications increased.

While the concern about the effects of medications on fertility and pregnancy is legitimate, it has been suggested there are other reasons women have historically been excluded from these studies. Women's menstrual cycles can complicate study results, as can the use of birth control pills to prevent pregnancy. Also, it was felt that because women were frequently caregivers for others, their responsibilities may make them "less reliable," or less available to participate in research.

Through the 1980s and '90s, advocates for women's health research challenged these notions, arguing that information provided by clinical trials was at best not particularly helpful, and at worst dangerous. The size of medication doses based on studies in men can lead to giving women doses that are too high, and some side effects may occur only in women. They also argued that reasons for excluding women from trials were not always valid, and were in fact just the reasons why medications should also be studied in women.

Finally in 1997, Health Canada published a policy that requires women be included in clinical trials. Other factors have also improved access to information about the use of medications in women, such as increased funding for women's health initiatives and the investigation of new uses for older medications, such as using antidepressants to treat severe premenstrual symptoms.

There are still outstanding issues to be resolved, however. Women are now usually included in the studies, but the results for each sex are not always analyzed or reported separately. Some assume that this means that there were no differences found, but this is not always the case; sometimes differences in efficacy and safety can be subtle.

Also, while studies may report data for sex differences, they rarely address differences due to gender. Sex refers to biological differences, while gender refers to social differences. For example, some studies of antidepressants have shown different responses in men and women, but have not determined if that is due to differences in their bodies, or the possibility that women and men may have different expectations for what 'response' is.

Not including pregnant women in studies may seem to make sense, but there are disorders that must be treated even in pregnancy. Because studies in pregnant women are rare, current knowledge is based on case reports of women who decided that the possible risks of the medication were less than the risk posed by their medical condition. A good argument for careful clinical trials in pregnancy was provided when a study with AZT, a drug used to treat AIDS, was started  in HIV-positive women, and was stopped early because the results were so positive.

Despite their usefulness, remember that clinical trials also have limitations; they cannot always predict extremely rare side effects, or interactions with all medications, or how any particular individual will react. Healthcare professionals also rely on case reports in journals and newsletters, the expertise of their colleagues and their own experience. The Internet also provides an exciting new opportunity for both healthcare providers and patients to access information. While the information on websites and newsgroups must be used along with official information and good judgment, it can help people with rare reactions find  each other and share  their experiences.

So, to answer your original question, while there was a time that clinical trials were conducted mainly in men, current regulations and practices ensure women are also included. Also, even before women were officially included in studies, experience and other types  of research helped healthcare providers and women make decisions about the safety of medications.

But even with improvements in the availability of useful information about medications in different groups, we have to remember that each patient is still an individual. Healthcare providers can use available published information and their experience, but must still take into account individual differences. It is important for patients to tell healthcare providers what they expect from treatment and how they are reacting to a medication, to make sure it is the best treatment for that person!

There are some good resources available that you can check out for information on women's mental health including <www.oursistersplace.com>.

Also, CAMH has a useful resource called: Is it Safe for My Baby? Risks and Recommendations for the Use of Medication, Alcohol, Tobacco and Other Drugs During Pregnancy and Breastfeeding. Call 1-800-661-1111 (or (416) 595-6059 in Toronto) or e-mail <mclaughlininformation@camh.net>, or fax (416) 593-4694 to request a copy. Information on addiction and mental health issues can be obtained by calling CAMH's 24-hour Information Line at 1-800-463-6273 or in Toronto at (416) 595-6111.

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